Lets see what happens

How to Interface GPS Module with Raspberry Pi 4

Welcome to the next tutorial of our raspberry pi four programming course. Before, we saw how to connect a Raspberry Pi 4 to a relay with four independent channels. To complement the relay circuit, we programmed a python script to turn on and off a single bulb. However, in this tutorial, we'll show you how to connect a GPS module to a Raspberry Pi 4.

Raspberry Pi 4, one of the most popular embedded platforms, has made it simple for developers to obtain location data via a GPS module, allowing them to create devices with a greater reliance on precise positioning. Because of the Raspberry Pi's impressive processing capabilities, this essay focuses on the exciting prospect of creating GPS-based projects using the same inexpensive GPS chips.

Since this project aims to retrieve location information (longitude and latitude) from a GPS module through UART and display it on a 16x2 LCD, this is yet another excellent chance to become acquainted with the 16x2 LCD and the Raspberry Pi.

Components

  1. Raspberry Pi 4

  2. Neo 6m v2 GPS Module

  3. 16 x 2 LCD

  4. Internet

  5. Breadboard 

  6. Jumper wires

  7. Resistor or potentiometer

In addition, we'll install the GPS Daemon library and the 16x2 LCD Adafruit library later in this guide.

The Raspberry Pi 4 running Raspbian OS is being used in this example. You can find a rundown of the minimum necessary hardware and software in Raspberry Pi's introductory instruction.

How does a GPS module function?

The acronym "GPS" stands for "Global Positioning System," and it is used to determine the precise Longitude and Latitude of any point on Earth and the current UTC time. The core of every GPS tracking system is a GPS module installed in the vehicle. This gadget gets up-to-the-second satellite coordinates along with the time and date.

Using the NMEA protocol, a GPS module transmits a plethora of position-tracking data in real time, as shown below. The NMEA format includes multiple sentences, yet only one is necessary. Coordinates, time, and other pertinent data begin at $GPGGA in this phrase. This information is known as GPS Fix Data or Global Positioning System Geodetic Reference Frame Data. 

We can determine its coordinates by using a simple count of commas in the $GPGGA string. If you locate the $GPGGA string and place it in an array, you can get the Latitude value two commas later and the Longitude value four commas subsequently. These coordinates for longitude and latitude can now be used in other datasets.

The $GPGGA String and its explanation are listed below.

$GPGGA,HHMMSS.SSS, latitude, N, longitude, E, FQ, NOS, HDP, altitude, M, height, M,, checksum data

The GPS module

You can use the NEO-6MV2 as your own personal GPS receiver everywhere you go. The GPS receiver communicates with the satellite network to determine its precise location. The device then sends forth serial data representing its current location, including its latitude and longitude.

The NEO-6 module uses a ublox-6 positioning engine with 50 channels and a TTFF of one second. The massive parallel time-space searches are made possible by the two million correlators in this GPS engine. As a result, it can rapidly locate satellites. The module's compact size also makes it a good fit for portable electronics that run on batteries.

It takes a voltage between 2.7V and 3.6V to power the NEO-6M GPS modem. The NMEA protocols are used for the communication of GPS data. While NMEA is an industry-standard ASCII format, UBX is a proprietary binary format developed by u-blox.

Data can be transmitted using any I2C-compliant interfaces on the receiver chipset, including Universal Asynchronous Receiver Transceiver (UART), USB, SPI, or DDC. There are three configuration pins on the chip. Pin CFG-GPS0 is used to set the power mode at boot.

Choose between the NMEA and UBX protocols for transmitting GPS data using CFG COM0 and CFG COM1.

This module employs a NEO-6 modem that has already been configured for serial (UART) output and NMEA encoding GPS data.

By setting the config pins CFG COM0 and CFG COM1 to HIGH, the GPS data is transmitted via the NMEA protocol at 9600 bps. The above table demonstrates that the NMEA data in this setup contains GSV, RMC, GSA, GGA, GLL, and VTG signals.

Here is a pin diagram showing the module's four available channels:

The module's top update rate for its navigation system is 5 Hz. So, in no more than 0.2 seconds, a controller can retrieve the Gps coordinates from the modem.

The 32-second cold start, 23-second warm start, and 1-second hot start times are all measured when the modem is turned on. Getting the first GPS reading takes 32 seconds because the module is set up for a cold start.

The module includes an external antenna with a frequency of -160dBm. Both an EEPROM and real-time clock (RTC) are built into the module, and the module also features a battery for backup. Temperatures from -40 to 85 degrees Celsius are within the NEO-6M modem's operational range. 

Getting a Raspberry Pi set up for GPS communication

To get started, I'll assume you're familiar with the Raspberry Pi and know how to install an operating system, find your IP address, and launch a terminal app like PuTTY. If you have any questions or need assistance, please let me know in the comments area.

The most challenging aspect of this project is getting the Raspberry Pi 4 set up so that it can talk to the GPS module over UART; trust me, I know; this is the first time I've done it, and it took me a few tries to get it right.

Functioning of the UART in Communication

UART communication involves a one-to-one connection between two UARTs. One UART does the serial-to-parallel conversion for data coming from a CPU and then sends that serial data to another UART, which does the reverse for data coming into its receiving device. When connecting two UARTs, you must use two wires to send and receive data. As information is transmitted from one UART to another, it travels from the broadcasting UART's Tx pin to the receiving UART's Rx pin.

The bits sent out by the sending UART are not necessarily in sync with the bits sampled by the receiver UART since UARTs send data asynchronously. The transmitting UART appends the packet's start and stops bits rather than sending a clock signal. This information tells the receiving UART where to begin reading the data packet and where it should stop.

Once the receiving UART recognizes a start bit, it will begin decoding the incoming data at the pace determined by the baud rate. The speed of information transmission, in bits per second, is referred to as the "baud rate" (bps). The baud rate of both UARTs must be roughly equivalent. Bit timing inaccuracies can occur when the baud rate difference between the sending and receiving UARTs exceeds 10%.

The data packet structure being transmitted and received by both UARTs must be identical.

The data for transmission arrives on a data bus and is picked up by the UART. To communicate with the UART, devices like the CPU, RAM, and microcontroller use a data bus. The transmitting UART receives data in a parallel fashion from the data bus. The data packet is created when the transmitting UART takes the parallel data from a data bus and adds a stop bit, a parity bit, and a start bit. The packet's data is sent out serially, one byte at a time, through the Tx pin. A data packet is sent and received serially through the Rx pin on the receiving UART. The UART decodes the data and restores it to its original parallel format, discarding the stop bit, parity bit, and start bit along the way. The data packet is then transferred in parallel from the receiving UART to the data bus:

Data packets are the standard for transmitting information via UART. There is one start bit, five to nine data bits (determined by the UART), one or two parity bits, and one or two stop bits in each packet.

The Raspberry Pi includes a PL011 and a small UART as onboard UARTs. Because of the unique hardware building pieces they employ, their overall performance and other attributes will vary slightly. Contrarily, the raspberry pi's tiny UART is utilized for the Linux console output, while the PLO11 UART is linked to the wireless/Bluetooth module.

The PLO11's higher implementation level makes it the superior of the two UART options. Accordingly, we'll use an overlay in the most recent version of Raspbian OS to turn off the Bluetooth module on the PLO11 UART for this project.

Step 1: Update the Raspberry Pi

To get started on any new project, I always start by upgrading the raspberry pi. Therefore, let's do the standard procedure and execute the commands below;

sudo apt-get update

sudo apt-get upgrade

and then restart the computer using;

sudo reboot

Step 2: Set up the UART

Within this context, we will initially modify the /boot/config.txt file. Please use the following instructions to accomplish this:

sudo nano /boot/config.txt

Place the following lines at the end of the config.txt file:

dtparam=spi=on

dtoverlay=pi3-disable-bt

core_freq=250

enable_uart=1

force_turbo=1

You can leave with Ctrl+X and save with Y + Enter.

Incorrect settings could prevent your Raspberry Pi from starting up, so please double-check everything.

Why are we issuing these commands? Because force turbo causes UART to operate at its maximum core frequency, which we have set to 250 MHz. This is done to protect the reliability and validity of the received serial data. Force turbo=1 will now void your Raspberry Pi's warranty, but other than that, it's safe to use.

We are disabling Bluetooth on the Raspberry Pi 3 using the dtoverlay=pi3-disable-bt so that we may use the full power of the UART on ttyAMAO rather than the small UART on ttyS0.

The second step in configuring the UART is to modify the boot/cmdline.txt file.

Before making any changes to the cmdline.txt file, you should save a copy in case you need to revert to the original version. A few ways to accomplish this are;

sudo cp boot/cmdline.txt boot/cmdline_backup.txt

sudo nano /boot.cmdline.txt

Substitute the following for the current text;

dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles

save your work and exit.

After this is complete, another system reboot is required before the new settings may take effect (sudo reboot).

Step3: Disable the Pi 4 Serial Getty Service

Next, we'll issue a command that will block the Pi's serial getty service from starting automatically upon reboot:

sudo systemctl stop serial-getty@ttyS0.service

sudo systemctl disable serial-getty@ttyS0.service

If you ever need to turn it back on, use these commands.

sudo systemctl enable serial-getty@ttyS0.service

sudo systemctl start serial-getty@ttyS0.service

Reboot your pi 4.

Step 4: Activate ttyAMAO:

Now that ttyS0 is no longer active, we can turn on ttyAMAO.

sudo systemctl enable serial-getty@ttyAMA0.service

Step5: Install Minicom and pynmea2:

We'll establish communication with the GPS unit and decipher its readings using minicom. In addition, we will use it to ensure that our GPS component is functioning correctly. Daemon software GPSD is an alternative to minicom.

sudo apt-get install minicom

We'll employ the pynmea2 library to quickly and conveniently process incoming information. Installing it necessitates;

sudo pip install pynmea2

Step 6: Install the LCD Library:

The AdaFruit library will serve as the basis for this tutorial. While the library's primary target was AdaFruit displays, it can also be used with HD44780-based display boards. In such a case, your display should function normally.

The library should be cloned and installed immediately. to conduct a cloning run;

git clone https://github.com/adafruit/Adafruit_Python_CharLCD.git

Go to the location where the clone was made and install it.

cd ./Adafruit_Python_CharLCD

sudo python setup.py install

It's time for another restart so we can move on to plugging in the parts.

Circuit diagram

Referring to the schematic below, attach the GPS Module and the Liquid crystal display to the Raspberry Pi.

Connecting the GPS module to a Raspberry Pi is as simple as powering it from the 3.3V pin and grounding it via any other RPi ground pins.

Following this, link the module's transmit (TX) pin to the Raspberry Pi's receive (Rxd) UART pin (board pin 10).

Testing the GPS module

Before we jump into the python script, it's best to use minicom to verify the GPS module's connectivity. Type the command and hit Enter.

sudo minicom -D/dev/ttyAMA0 -b9600

Where 9600 is the baud rate the GPS module uses to transmit data. Once we have verified that our GPS and RPI can exchange data with one another and script development can begin.

Cat can also be used for the test.

sudo cat /dev/ttyAMA0

All of the previously discussed NMEA sentences will appear in Window. As shown in the figure below, a module's status LED will begin blinking if the GPS receiver detects satellites in the sky and begins to fixate on its location.

Now that everything has been set up, we can put it through its paces. Your GPS may need to be outside to acquire a good satellite lock (often, three or four are required; however, I was able to use mine indoors).

Complete code

import time

import serial

import string

import pynmea2

import RPi GPIO as gpio

#to add the LCD library

import Adafruit_CharLCD as LCD

gpio.setmode(gpio.BCM)

#declaring LCD pins

lcd_rs = 17

lcd_en = 18

lcd_d4 = 27

lcd_d5 = 22

lcd_d6 = 23

lcd_d7 = 10

lcd_backlight = 2

lcd_columns = 16 #Lcd column

lcd_rows = 2 #number of LCD rows

lcd = LCD.Adafruit_CharLCD(lcd = LCD.Adafruit_CharLCD(lcd_rs, lcd_en, lcd_d4, lcd_d5, lcd_d6, lcd_d7, lcd_columns, lcd_rows, lcd_backlight)

port = "/dev/ttyAMA0" # the serial port to which the pi is connected.

#create a serial object

ser = serial.Serial(port, baudrate = 9600, timeout = 0.5)

while 1:

    try:

        data = ser.readline()

    except:

print("loading") 

#wait for the serial port to churn out data

    if data[0:6] == '$GPGGA': # the long and lat data are always contained in the GPGGA string of the NMEA data

        msg = pynmea2.parse(data)

#parse the latitude and print

        latval = msg.lat

concatlat = "lat:" + str(latval)

        print concatlat

lcd.set_cursor(0,0)

lcd.message(concatlat)

#parse the longitude and print

longval = msg.lon

concatlong = "long:"+ str(longval)

print concatlong

lcd.set_cursor(0,1)

lcd.message(concatlong)

    time.sleep(0.5)#wait a little before picking the next data.

Output

Conclusion

This tutorial covered the basics of installing a GPS tracker on a Raspberry Pi 4. What we know about UART and the NMEA protocol has expanded as well. Numerous new possibilities for the exploration of the idea are now available. You could, for instance, construct a system for tracking vehicles, drones, or the weather. In addition to being inexpensive and simple to install, GPS modules are becoming increasingly popular. They can be frustrating because of their slow data extraction and spotty reception. However, they perform wonderfully in the open air. Next, we'll look at how to interface the BMP180 air pressure sensor to a Raspberry Pi 4.

Interface BMP180 Air Pressure Sensor with Raspberry Pi 4

Hello friends, I hope you all are doing well. Today, I am going to share the 8th tutorial of Section-III in our Raspberry Pi Programming Series. In the previous tutorial, we interfaced the temperature sensor DS18B20 with Raspberry Pi 4. In today's guide, we'll discover another temperature sensor BMP180 and will interface it with Raspberry Pi 4.

So, let's get started:

Project Description

In today's tutorial, we will interface the BMP180 sensor with Raspberry Pi 4 and will display the values of temperature, barometric pressure and altitude in the Raspberry Pi Console Window.

Components Required

We will use the following components in today's project:

  • Raspberry pi 4
  • BMP180 sensor
  • Female-Female Jumper wires
  • Breadboard

BMP180 Air Pressure Sensor

  • BMP180 is a low-cost sensor designed by Bosch to measure the temperature and barometric pressure.
  • As it can measure the pressure, so we can also get the altitude value from BMP180.
  • It follows the I2C protocol to communicate with microcontrollers.
  • Its a successor of the BMP085 sensor, a more accurate and precise model, shown in the below figure:

BMP180 Working Principle

Pressure can be measured with the BMP180 piezoresistive sensor. Semiconducting (often silicon) piezoresistive sensors respond to mechanical forces such as air pressure by shifting their resistance value.

Because air density changes with temperature, the BMP180 collects data on both pressure and temperature. Warmer air is less dense and lighter; therefore, it exerts less force on the sensor. Because the atmosphere at lower temperatures is thicker and heavier, it presses the sensor more. The sensor takes real-time temperature values to adjust for air density variations.

The BMP180 provides raw temperature (UT) and pressure(UP) readings. A reading of the pressure is taken after the temperature has been recorded. Measurement processing at the sensor is depicted in this flowchart:

The 11 individual calibration coefficients for the BMP180 are stored in the sensor's 176-bit EEPROM. Together with the UP and UT, these are needed to determine the actual atmospheric pressure and temperature. It takes some advanced algorithms to determine the exact pressure and temperature:

I2C Working Principle

I2C Protocol is designed to communicate between several devices with a single bus simultaneously. I2C uses the address frame for selecting a slave device to communicate.

Depending on the application, I2C slave addresses might be 7 or 10 bits in length. This requires sending not one but two addresses across the bus in two separate address frames. A specific 7-bit address of 0x92 is used for the first location. A second address frame, intended for 10-bit machines, comes just after the unique address. This is how devices with 10-bit addresses can coexist on a bus with devices having 7-bit addresses without causing any incompatibilities.

If you're using I2C, you can use either of its two unique slave-handling modes. Information can flow in both directions between the Master and the slave. I2C read/write bit comes immediately after the address bit. The Master sends a read bit to the slave by making the line high when it wants to accept data from the slave. A write bit is sent from the Master to the slave by grounding the connection.

The placement of the Raspberry Pi's I2C pins is depicted in the following diagram:

Install Python I2C Tools

First, you'll need to turn the I2C drivers on your Raspberry Pi.

Enter the raspi-config command as sudo. Select Menu Item #8 (Advanced Settings). Choose A7 I2C, confirm your acceptance when prompted to activate the I2C driver, then confirm your acceptance once more to load the drivers automatically. Return to the command prompt and type sudo reboot to restart your Raspberry Pi.

Be sure to include i2c-dev in /etc/modules.

sudo nano /etc/modules

After that, at the prompt, type:

sudo modprobe i2c-dev

Verify that i2c modules have been loaded and are functioning:

lsmod  | grep i2c

  • Install some i2c tools:

I2c-tools has some neat programs like "i2cdetect", which lists all the slave devices on a bus by their addresses. To test it out, connect the sensor and run "sudo i2cdetect" with the -y parameter set to 1. In addition, "i2cdump" is a tool that may be used to determine the configuration of a single I2C device by reading its registers. Using the below connection details and the sensor's factory settings (address 0x77), you should see the following output:

The BMP180 has been detected on channel 77.

Circuit Diagram of BMP180 with Raspberry Pi 4

You only need a breadboard and some female-to-male jumper wires to hook up the sensor to your Pi 4. Before plugging in any peripherals, you should always shut down your Raspberry Pi. Type the following command and watch for the green LED to turn off:

sudo shutdown -h now

The BMP180 can be linked to a Raspberry Pi by following the instructions below. There are a few variations of the BMP180 boards, so keep that in mind. The BMP180 is the part number for the chip rather than the entire board; therefore, your board may have 4, 5, or 6 pins.

With the Raspberry Pi oriented as indicated above, the diagram below shows how the jumper wires should be connected.

  • The red jumper connects the input VCC pin of the sensor to the 3v3 pin of the Pi 4.

  • The yellow jumper connects the Raspberry Pi's SDA pin to the BMP180's SCL pin. This wire is used for communication between the BMP180 and the Raspberry Pi.

  • Connecting the Raspberry Pi's SCL pin to the BMP180's SCL pin is a blue jumper wire that goes from the third pin on the top row to the right. i2c devices use the clock signal provided by this pin to synchronize their communication with the Raspberry Pi's clock.

  • Any of the Raspberry Pi's ground (GND) pins can be connected to the BMP180's GND pin with the help of the black jumper.

Verify all wires are securely attached before powering up any devices. While it's doubtful anything horrible will happen, double-checking before pushing the button is still a good idea.

Python Code for BMP180 and RPi4

For Python to understand the BMP180's output, we must install the necessary libraries. The Adafruit libraries were initially developed to be utilized by BMP085, the BMP180's predecessor, but the compatibility between the chips means they can also be used with the BMP180.

Type this into the Raspberry Pi's shell to install the necessary Python and the libraries above.

sudo apt-get install build-essential python-dev python-smbus 

Please make a new Py file in your home directory and give it the name BM180.py. Then, paste the code below into the new file. The code is well-commented, so it shouldn't be too difficult to understand.

Complete code

import smbus

import time

# Get I2C bus

bus = smbus.SMBus(1)

# BMP180 address, 0x77(119)

# Read data back from 0xAA(170), 22 bytes

data = bus.read_i2c_block_data(0x77, 0xAA, 22)

# Convert the data

AC1 = data[0] * 256 + data[1]

if AC1 > 32767 :

AC1 -= 65535

AC2 = data[2] * 256 + data[3]

if AC2 > 32767 :

AC2 -= 65535

AC3 = data[4] * 256 + data[5]

if AC3 > 32767 :

AC3 -= 65535

AC4 = data[6] * 256 + data[7]

AC5 = data[8] * 256 + data[9]

AC6 = data[10] * 256 + data[11]

B1 = data[12] * 256 + data[13]

if B1 > 32767 :

B1 -= 65535

B2 = data[14] * 256 + data[15]

if B2 > 32767 :

B2 -= 65535

MB = data[16] * 256 + data[17]

if MB > 32767 :

MB -= 65535

MC = data[18] * 256 + data[19]

if MC > 32767 :

MC -= 65535

MD = data[20] * 256 + data[21]

if MD > 32767 :

MD -= 65535

time.sleep(0.5)

# BMP180 address, 0x77(119)

# Select measurement control register, 0xF4(244)

# 0x2E(46) Enable temperature measurement

bus.write_byte_data(0x77, 0xF4, 0x2E)

time.sleep(0.5)

# BMP180 address, 0x77(119)

# Read data back from 0xF6(246), 2 bytes

# temp MSB, temp LSB

data = bus.read_i2c_block_data(0x77, 0xF6, 2)

# Convert the data

temp = data[0] * 256 + data[1]

# BMP180 address, 0x77(119)

# Select measurement control register, 0xF4(244)

# 0x74(116) Enable pressure measurement, OSS = 1

bus.write_byte_data(0x77, 0xF4, 0x74)

time.sleep(0.5)

# BMP180 address, 0x77(119)

# Read data back from 0xF6(246), 3 bytes

# pres MSB1, pres MSB, pres LSB

data = bus.read_i2c_block_data(0x77, 0xF6, 3)

# Convert the data

pres = ((data[0] * 65536) + (data[1] * 256) + data[2]) / 128

# Callibration for Temperature

X1 = (temp - AC6) * AC5 / 32768.0

X2 = (MC * 2048.0) / (X1 + MD)

B5 = X1 + X2

cTemp = ((B5 + 8.0) / 16.0) / 10.0

fTemp = cTemp * 1.8 + 32

# Calibration for Pressure

B6 = B5 - 4000

X1 = (B2 * (B6 * B6 / 4096.0)) / 2048.0

X2 = AC2 * B6 / 2048.0

X3 = X1 + X2

B3 = (((AC1 * 4 + X3) * 2) + 2) / 4.0

X1 = AC3 * B6 / 8192.0

X2 = (B1 * (B6 * B6 / 2048.0)) / 65536.0

X3 = ((X1 + X2) + 2) / 4.0

B4 = AC4 * (X3 + 32768) / 32768.0

B7 = ((pres - B3) * (25000.0))

pressure = 0.0

if B7 < 2147483648L :

pressure = (B7 * 2) / B4

else :

pressure = (B7 / B4) * 2

X1 = (pressure / 256.0) * (pressure / 256.0)

X1 = (X1 * 3038.0) / 65536.0

X2 = ((-7357) * pressure) / 65536.0

pressure = (pressure + (X1 + X2 + 3791) / 16.0) / 100

# Calculate Altitude

altitude = 44330 * (1 - ((pressure / 1013.25) ** 0.1903))

# Output data to screen

print "Altitude : %.2f m" %altitude

print "Pressure : %.2f hPa " %pressure

print "Temperature in Celsius : %.2f C" %cTemp

print "Temperature in Fahrenheit : %.2f F" %fTemp

Output

Is it possible to use several BMP sensors on one board?

Usually, only one device on the I2C bus is assigned to address 0x77 because each device on the bus requires its unique address (etc.). It is possible to use numerous devices on the same address, but each device will demand its GPIO pin in exchange. This is useful if you connect multiple I2C devices to the same address, like the BMP085. By holding the XCLR pin low, you can force all devices on the I2C bus to reset while freeing the rest of the one you wish to read and making it respond to any request.

Predicting the weather with a pressure sensor

Forecasting the weather with changes in pressure sensors is possible. An increase in the amount of air above the surface of the Earth causes the barometric pressure to drop. As the air rises, it leaves a vacuum that creates a low-pressure zone on the ground. Air mass cools and condenses as it rises in height. The result is clouds that can eventually turn into the rain because of the condensation of atmospheric moisture. The wind is also often present as the surface air flows into low-pressure areas.

When air from higher in the stratosphere sinks to Earth, the result is a rise in atmospheric pressure. The air pressure beneath the surface is raised as the falling mass exerts pressure on the ground. The air mass is cooler and denser at lower altitudes, but at higher altitudes, it warms up and expands. Because of the low humidity of the heated expanding air, clouds are rarely seen during this weather phenomenon. In general, increasing barometric pressures precede the arrival of pleasant, bright days.

Conclusion

Here, we learned how to connect a BMP180 sensor to a Raspberry Pi 4. We have also researched the 12c protocol's operation to ensure successful sensor-to-pi 4 communication. Several tasks call for the interesting BMP180 sensor. Even though it has been retired from production, a comprehensive data sheet is still accessible online. The values provided by the module can be read and manipulated with only a basic shell script. Even though it's a major undertaking, learning to compile your kernel can help you better grasp Linux. The following tutorial will teach you how to connect the MQ-2 Gas Sensor with a Raspberry Pi 4.

How to Interface MQ-2 gas sensor with Raspberry Pi 4

Hello friends, I hope you all are having fun. Today, I am going to share the 9th tutorial of Section-III in our Raspberry Pi 4 Programming Course. In the previous tutorial, we interfaced an air pressure sensor BMP180 with Raspberry Pi 4. In this tutorial, you'll learn how to interface an MQ-2 gas sensor with a Raspberry Pi 4.

Many apartments, residences, and workplaces rely heavily on these gas sensors to detect smoke or gas and alert the appropriate personnel in an emergency. In addition to gas and smoke, this sensor is sensitive to various odorous gases.

Project Description

Today, we will interface a gas sensor MQ-2 with Raspberry Pi 4 and will display the values on Raspberry Pi Console Window.

Components Required

These are the components used in today's project:

  • Raspberry Pi 4
  • MQ-2 Smoke Sensor
  • MCP3002 ADC

MQ-2 Gas Sensor Pinout

  • MQ-2 is a low-cost electronic sensor, used to sense the intensity of gases in the surrounding.
  • MQ-x(MQ-1 to MQ-9) is a family of gas sensors used to detect different kinds of gases in the environment i.e. methane, propane, hydrogen etc.
  • The MQ-2 gas sensor is used in security systems to detect potentially dangerous gases or flammable smoke.
  • MQ-x sensors are inexpensive, simple-to-operate with an extended sensing range that may be narrowed to control the level of sensitivity.

  • The MQ-2 Gas sensor contains four inputs, two of which are reserved for Vcc and GND, and the remaining two can concurrently output digital and analog data.
  • The image above reveals that the module incorporates two onboard LEDs. When power is provided to the board, the power LED lights up, while the Dout LED lights up when the potentiometer's trigger value is achieved.
  • When an analog signal is received from the gas sensor, the board's integrated comparator OP-Amp converts it to a digital one.
  • In addition, the device's sensitivity can also be fine-tuned using the included Trim-pot.

Now let's have a look at the Mq-2 Pinout:

MQ-2 Pinout

Here's the pinout diagram of MQ-2 sensor:

  • Vcc: The VCC pin on the Gas Sensor is its power input and is connected to 5V.
  • GND: The board's ground, denoted by the symbol GND, must be linked to the ground pin.
  • Dout: Pin Dout is the board's digital output; a low reading indicates the absence of gas or smoke, while a high reading indicates its presence.
  • Aout: The board's Analog output pin will provide an analog signal between the Vcc input and ground, denoted by the symbol "Aout", depending on the measured gas intensity.

How does the gas sensor function?

To correctly identify combustible glasses, the MQ-2 gas sensor employs a heating element; however, having such a component close to combustible gases would be catastrophic, so the sensor is built with anti-explosion protection consisting of two thin lines of stainless steel mesh, as can be seen in the image below. In this case, the stainless steel mesh houses the heating element.

Its mesh structure not only blocks out solids like dust and dirt but also keeps out particles in the air that are too big to be gaseous, such as oxygen and nitrogen. In this case, decapitating the sensor reveals that it consists of two main parts. The nichrome wire that does the heating is accompanied by a platinum wire that has been coated with tin dioxide for the sensing part. We have already removed the protective cap to prevent you from accidentally slicing your sensor, as shown in the figure below.

After the mesh is taken off, the sensor reveals its proper form. Stainless steel mesh was cut and attached to the sensor's housing, as shown in the top image. The sensory component that we have been discussing is now readily apparent. Since the actual detecting and heating element is attached to the sensor's six legs in a star configuration, the sensor's pins also take on that shape. Bakelite, used to increase the sensor's heat conductivity, is visible at the base of the device (black).

Module MQ-2 Gas Sensor Internal Design

Here is a pictorial representation of the circuitry inside the MQ-2 gas sensor module. This module's schematic is quite elementary, and its construction requires only a few essential parts. The following schematic could be helpful if you need to construct this circuit quickly:

The LM393 op-amp is shown in the diagram; it is a +5V-powered, low-power op-amp with a small offset voltage. The MQ-2 sensor requires at least 5V, so 3.3V can't be used to power the circuit. This op-amp is primarily responsible for performing the digital-to-analog conversion of analog input signals. In addition, the MQ-2 Sensor module's sensitivity and triggering voltage can be fine-tuned via an onboard 10K potentiometer. In addition, there are two LED lights. As soon as power is supplied to the board, the power LED lights up, while the trigger LED lights up when a predetermined threshold is met. A pair of decoupling capacitors helps keep the board quiet.

MQ-2 gas sensor preheating time:

It would be best if you let the gas sensor stabilize after being preheated before you can use it. Moreover, a 24-hour preheat period is specified on the device's datasheet. Does this indicate that it must be on for 24hrs before being used?

The resounding "NO" is the clear response to this inquiry. This only denotes that a continuous 24-hour run is required to acquire the typical performance figures in the datasheet. And after 24 hours in their lab, they measured it. To stay within tolerance, you must adhere to the specified preheating time of 24 hours. Considering the small space, the sensor should reach temperature equilibrium in under 30 minutes. Nevertheless, you may get results within a few percentage points of the datasheets in minutes.

Suppose you need a precise reading of the gas concentration. In that case, you should preheat your sensor for 24 hours, ensure it is properly calibrated, and find a way to account for ambient variables such as temperature and humidity.

With the MQ-2 Gas sensor, you can do more than detect the presence of butane and hydrogen gas; you can also measure the concentration of these gases in parts per million. Detecting the gas and determining its concentration in parts per million are two very different processes. Detecting a gas's level and subsequent increase in concentration is the primary subject of this essay. In addition, we will briefly touch on precisely calculating the gas concentration in parts per million, for which a different method is required.

Liquefied Petroleum Gas, Butane, and Hydrogen Detection Using the MQ-2

A can of LPG gas is shown above; when the gas is sprayed, the surrounding concentration of gas increases; repeating the process results in even higher gas concentrations. The multimeter will show an increase in the sensor's voltage reading as the gas concentration rises. Also, the module's green LED will illuminate when it hits the user-defined threshold.

Raspberry Pi MQ-2 Detector Circuit Diagram

The smoke sensor is powered by connecting pin 2 to the 5V connector and pin three to the GND terminal on pi 4. This provides the 5 volts that are required to power the smoke detector.

Our application will be set up to turn on the light when the smoke detector's voltage rises above a user-defined threshold.

Now that we've established the physical links, all that's missing is the software we've been developing.

Complete code

import RPi.GPIO as GPIO

import time

GPIO.setmode(GPIO.BCM)

GPIO.setwarnings(False)

GPIO.setup(14,GPIO.IN)

GPIO.setup(12,GPIO.OUT)

GPIO.output(12,False)

while True:

    button_state=GPIO.input(12)

    if button_state == False:

        GPIO.output(12,True)

        while GPIO.input(14) == False:

            time.sleep(0.2)

    else:

        GPIO.output(12,False)

Output

Conclusion

Follow the steps in this tutorial. You should be able to connect the MQ-2 sensor to a breadboard and a Raspberry Pi, turn on the SPI interface, and then read sensor values using the most recent Circuit Python library. You can accomplish the same thing for additional MQ-x sensors by modifying the file depending on the sensor's design and then connecting each sensor to a separate MCP3008 channel to read its values simultaneously. The following tutorial will teach you how to use a Raspberry Pi 4 with BLE to manage your household gadgets.

Programming on Node.JS: A Comprehensive Guide

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Programmers use different programming languages so that they can create front-end and back-end applications well. One of the people’s main choices is Node.js. This particular programming language allows the creation of applications using JavaScript.

What Exactly is Node.js?

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Node.js is usually the choice of programmers because it is open-source. What does this mean? It means that the source code for it is readily available. Contributors from different parts of the world are maintaining the source code.

Node.js cannot be properly used without the right developer. A dedicated Nodejs developer is always in demand. More people are learning how to use this programming language. Yet, a person should always be interested, dedicated, and passionate about it.

Some Advantages of Node.js

Some programmers who are still searching for a programming language to focus on can start learning Node.js for the following advantages:

  • This can be used for both the front-end and the back-end of the application. This means that programming can be done and fixed on both the client and server side.

  • The community of this programming language has grown steadily over the past years. It is still expected to grow bigger and better with more contributions to help any Nodejs developer .

  • The demand is only expected to grow as more well-known applications are using Node.js to improve their features.

Setting Up Node.js Development Environment

The first thing to do is to make sure that your account has administrator privileges. This means that you can choose the software that you want, download it, and install it on your device.

  1. Download Node.js Installer – Make sure to download the latest version.

  2. Install Node.js and NPM from your chosen web browser – The moment that download is complete, launch it. Follow the instructions that will be given to you.

  3. Verify the installation of Node.js – A command prompt will enter and you need to place “node-v”

Choosing an IDE or Text Editor for Node.js

You may ask yourself what type of JavaScript IDE will you use for Node.js? Different text editors are available but these are some things that can help:

  • Look for something that can be used by the whole node js development team. Some are more user-friendly than others.

  • Find the IDE that can help with syntax highlighting.

  • Refactoring options will always be very helpful. This will help you restructure the codes that you already have. It can make the editing of existing projects easier.

Basics of Node.js Programming

You can find react programmer that can make their knowledge and skills on providing what you need. Node.js is known for being event-driven and non-blocking which is confusing for people who haven’t learned enough about this yet.

When you say event-driven, it means that this can understand the request and do the task accordingly. A function will be created and will be registered instead of getting all the data. The function will work once it is triggered.

When you say non-blocking, it means that the request will be sent to the required function immediately. The request will not be blocked so it will be received at the soonest possible time.

Working with Modules, Callbacks, and Asynchronous Programming

When you say modules in Node.js, you are referring to a type of functionality that can be used in the Node.js application. Take note that the functionality can be simple or complex. It will depend on the number of JavaScript files that are available.

Callbacks, on the other hand, are the type of responses to an event. For example, when the user clicks on a button, the callback will make sure that something will happen. The application can take note that the same response should happen no matter who is using it.

Asynchronous programming works in such a way that other functions are already happening before the main function is done. This can make the response faster. To make this happen, Node.js needs to make use of the event loop that will dispatch the requests to C++. Once it receives the results, it will be sent back to JavaScript. This might seem long but this will only take a short time.

Building Web Applications with Node.js

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The HTTP module can be used by the node.js programmer to get an immediate response. To do this, the programmer simply needs to use the createServer ( ) method. This will run whenever someone tries to use the same computer.

Other important things to note are the following:

  • Routing – This is figuring out how the application will react to the client’s actions. Different routes are available and the route that the function will take depends on the action.

  • Middleware – This will have all the access to request or respond to an object.

  • Request Processing – You need to have the right command ready so that the request will be processed accordingly.

Working with Express.js

Express.js is the web application framework that is commonly used when you are using Node.js. This is the choice of a lot of people because it is simple yet flexible. Different features are available and they can be used for both apps and websites.

Setting Up Express.js

Remember that you cannot set up Express.js unless you already have Node.js on your device. Once this is done, you can do the following:

  1. Create a directory and make sure that it is working.

  2. Use the npim init command.

  3. Enter the name of the main file.

  4. Install Express in your directory.

Data Access and Database

Node js development can always be improved as long as all the bases are covered. To connect with the database, the programmer should have the appropriate drivers for it. The driver can be installed through a command prompt using the chosen text box. Once you have access, you will be able to go through your needed data.

The ORM can be used to represent the items that are available in the data. It will help you understand the relationship between the programs and the database. Some say that it is the layer that will hold all the information together.

Testing and Deployment

Unit testing is one of the most important things that programmers can do. This will ensure that even the smallest units are working properly. Each code will be isolated and tested so that if discrepancies are going to arise, these will be fixed. To make tests, some fake implementations will be inserted. The testers will check if the codes still react to those fake implementations.

There are different Node.js frameworks that you can choose from. Each framework has pros and cons. You need to consider the deployment options as well as how well the data will perform. You can choose from the following frameworks:

  • Jasmine

  • AVA

  • Mocha

  • Jest

Security and Best Practices

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Different vulnerabilities will always threaten your database. One of the most common vulnerabilities is loose comparison. This happens when the attacker will create something that will make the condition to be always true. True values will be returned to the attacker which can make the data more vulnerable. If the database is tricked, data from the users of the database will be retrieved. The best thing to do is to use mixed data types.

Another common vulnerability is prototype pollution. This type of vulnerability allows the attacker to take control of the data. The tampered data will not work the way that it is supposed to. The best thing to do to counter this is to use the object.assign method. This will help retrieve the data from the user so that it will be updated and corrected.

Interface a 4-Channel Relay with Raspberry Pi 4

We learned in the previous tutorial how to connect a joystick to a Raspberry Pi 4 using an mcp3008 and an op-amp IC, the LM324A. For each of the interface methods we studied, we created a python script allowing us to interact with the circuit. This tutorial will show you how to connect a 4-channel relay module with a Raspberry Pi to carry out switching.

A relay's primary function is to allow a circuit to be controlled by a weak signal. High-current applications necessitate relays to separate the low-voltage control circuit from the high-power driving circuits. Because of this, understanding it is crucial for those interested in industrial or household automation.

If you've been tinkering with a raspberry pi for a while, consider the various ways in which you might put it to use.

So let’s dive in!

Components

  • Four-channel 5V Relay Module

  • Raspberry pi 4 

  • A Few Jumper cables 

  • 5v power source

The raspberry pi has real-world uses, such as remotely turning a device on or off over the internet, sensors, or a mobile app communicating with the pi via Bluetooth. If we can master this, we will open up a world of possibilities.

Raspberry Pi as a Device Switch

Anybody who has experimented with a Raspberry Pi knows it has a GPIO.

The 40-pin general-purpose input/output (GPIO) connector is great for connecting various output devices. Since it is a digital computer, Raspberry Pi's GPIO pins can provide logic outputs. Logic 0 and 1 are the terms used to describe these two possible results from a logic circuit. If you write a program to make a Raspberry Pi pin write logic zero, you'll get a real-world GND potential. Likewise, when logic 1 is written on the Raspberry Pi pin, +3.3V is produced.

Logic 0 (gnd) and logic 1 (+3.3v) may be generated on any Raspberry Pi output pin with some programming. However, the output voltage is too low to power any real-world equipment. A maximum of 20 mA can be drawn from the output pin, as the 3.3V generated is currently limited. This only means that we can connect an LED straight to a Raspberry Pi gpio pin. In addition to the DC motor, no other output device can be connected directly to the raspberry pi's pin. Because of this, a different method is required when connecting an AC device.

How do relays work?

This image is a cross-sectional diagram of a relay's inner workings. A control coil encloses a core made of iron. When power is supplied to the control coil, an electromagnet begins to energize, boosting the strength of the magnetic field it produces. As a result, the top contact arm attracts the lower fixed arm, closing the contacts and completing the circuit. However, if the relay were de-energized before the connections were closed, the contacts would travel the opposite way, creating an open circuit. When the coil current is shut off, the spring will return the movable armature to its original position.

The operation of a relay is identical to that of a switch. This also means that the same principle applies. When a relay is used, one or even more poles are flipped. Each pole has two primary contact directions. They have NO contact, commonly known as the Normal Open Contact configuration. Connecting with someone is another name for this action. On activation, the relay completes the circuit. Once the relay is deactivated, the circuit is broken.

NC contact is short for normally closed contact. This is synonymous with the term "break contact." In contrast to "NO contact," communication will occur. By switching on the relay, the circuit is broken. As soon as the relay is turned off, the circuit is complete.

A relay's COM contact is shared by the normally closed (NC) and normally open (NO) contacts.

An example of a relay module with two channels is displayed here. As its name implies, a two-channel relay module consists of a circuit with two independent relays built in. This enables the simultaneous manipulation of two distinct gadgets. It follows that the greater the available channels, the more gadgets we can link together.

Let's connect the Pi 4 to the 2-channel relay now. With its four corresponding pins, the 2-channel relay may communicate with a Raspberry Pi. VCC, GND, IN1, and IN2 are the inputs. Current input higher than 30 mA and an input voltage of 5 V is required to power the relay module. As a result of this glaring current shortfall, we must rely on an external power source. Here, we'll employ the widely used MB102 Breadboard Power Supply, an external power supply board. If you're curious about this power source and why we decided to use it, there are some helpful links below. A 3.3 V Relay is what you'll need to operate with Relays without an external power supply.

The relay module's VCC pin must be connected to the power supply's 5 V pin. Then Join the Raspberry Pi 4's ground pin (GND) to the power supply's ground pin (GND). The next step is to attach a jumper wire between the power supply's second GND port and the Raspberry Pi's second GND port. As a result, the ground pin on the Pi 4, the relay switch, and the power source are now all connected. Last but not least, connect a push button to GPIO 2 to activate the relay. Let's connect a few high-powered gadgets across the relay's output now. As seen in the circuit schematic, a CFL is connected to the NC and COM ports.

Using a Relay as a Switching Circuit

As was previously mentioned, the RPi is a computer with an output range of only +3.3v to 0v. We need a dedicated electronic switching circuit to link any real-world device to the Raspberry Pi and enable it to switch. Assume throughout this lesson that you want to control an electrical lamp using raspberry pi. A switching circuit is required because we cannot wire the light bulb directly to the raspberry pi. There must be a switching circuit, such as a relay, to turn on and off AC appliances.

The following graphic depicts the internal structure of a relay.

Above, you can see that a basic relay has five connections. The electromagnetic coil's two ends, L1 and L2, serve as the magnet within the relay. Directly connecting the L1 Or L2 to a DC power supply is possible. The coil becomes an electromagnet when it is supplied with an electric current. Unlike the usually closed (NC) and ordinarily open (NO) terminals, the Common terminal can be moved.

Working of Relays

The NC terminal serves as the home of the common terminal, which is held in place using sprint tension. This is the relay's initial setting. In a standard setup, the NC and COM terminals of a relay are linked when the device is positioned on a flat surface. The coil becomes magnetized whenever a voltage is placed between coil terminals L1 and L2. The spring tension is opposed by the magnetic force that pulls the common terminal off of NC and onto NO. As long as the relay is live, there will be continuity between NO and COM. Magnetization ceases when the coil voltage is removed, and the common terminal reverts to the NC Terminal, as depicted below.

To conclude, we can switch any AC device on and off with a relay if we know how to do so effectively. However, the issue of activating the relay itself remains to be seen. Typically, relays require a voltage of 12v or 24v, which the Raspberry Pi cannot produce. A microprocessor cannot supply the 30-50mA current required for relays that operate on +5v coil voltage. Consequently, a relay switching circuit is required rather than a direct connection to the raspberry pi.

An explanation of relay control

By adjusting the voltage at the GPIO pins, you may toggle the state of any relay module, whether it's attached directly to the ports or via a relay HAT. Using Python in conjunction with the GPIO library is the simplest solution.

After establishing a connection to the desired GPIO pin, changing its state is as simple as issuing a single command in Python. Pins 26, 20, and 21 on the GPIO header are used for the Waveshare HAT relays. For this reason, for instance, the first relay's power supply can be switched after a delay of just one second.

Sample code

import time

import RPi.GPIO as GPIO

relay_ch = 26

GPIO.setwarnings(False)

GPIO.setmode(GPIO.BCM)

GPIO.setup(relay_ch, GPIO.OUT)

GPIO.output(relay_ch, GPIO.LOW)

time.sleep(1)

GPIO.output(relay_ch, GPIO.HIGH)

GPIO.cleanup()


Using a signal from a microcontroller like a Raspberry Pi, we can switch a DC load with a transistorized switching circuit. Just below, you'll find a quick breakdown of how transistors function.

Here is the complete circuit for using a transistor to switch a relay using a Raspberry Pi.

As demonstrated in the diagram above, the transistor controls the switching of the relay coil, while the relay terminals control the AC load. Any AC load can be connected to a Raspberry Pi using the circuit above and turned on or off remotely.

This setup makes use of the following Components:

  • Q1 = It can be any regular NPN transistor; we chose a BC548.

  • R1 = The resistor has a 330-ohm value.

  • D1 = inexpensive switching diodes such as 4148

  • RL1 = 12v Relay

Diode D1 is a protection device that allows the relay to be easily turned off, as shown in the diagram.

The transistor base resistor will receive the signal from the raspberry pi pin. Here's a program that will turn on a relay when the output is set to HIGH and turn it off when the output is set to LOW.

Sample code

led1 = 21 #GPIO pin to connect to relay

import RPi.GPIO as GPIO

import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(led1, GPIO.OUT)

while True:

    GPIO.output(led1, True)    

    time.sleep(2)

    GPIO.output(led1, False)

    time.sleep(2)

The function of transistors in a relay module.

A transistor can open and close an electronic gate millions of times per second, allowing electrical signals to pass through and out. As long as electricity flows, the circuit is active; otherwise, it is cut off. Modern telecommunications systems are built on complicated switching circuits that rely on transistors. Circuits can also flip at extremely fast rates, with some offering switching speeds of over 100 billion on/off cycles per second or hundreds of gigahertz.

A logic gate, constructed from several transistors, compares input currents and generates a unique result. Logic gates allow computers to use Boolean algebra to make straightforward decisions. Modern computers and software applications are built on these methods.

Four-channel relay module

A relay module can be easily controlled by connecting its signal pin to the GPIO on a Raspberry Pi and then applying the rated input voltage from the power supply. The necessary transistors and switching circuitry are already on this board. All you have to do to use such a relay module is connect the GND of the power source that powers the relay module (5v/12v/24v) to the GND of the raspberry pi. 

Python code for a 4-channel relay

import RPi.GPIO as GPIO

import time

Relay_Ch1 = 26

Relay_Ch2 = 20

Relay_Ch3 = 21

GPIO.setwarnings(False)

GPIO.setmode(GPIO.BCM)

GPIO.setup(Relay_Ch1,GPIO.OUT)

GPIO.setup(Relay_Ch2,GPIO.OUT)

GPIO.setup(Relay_Ch3,GPIO.OUT)

print("Setup The Relay Module is [success]")

try:

while True:

#Control the Channel 1

GPIO.output(Relay_Ch1,GPIO.LOW)

print("Channel 1:The Common Contact is access to the Normal Open Contact!")

time.sleep(0.5)

GPIO.output(Relay_Ch1,GPIO.HIGH)

print("Channel 1:The Common Contact is access to the Normal Closed Contact!\n")

time.sleep(0.5)

#Control the Channel 2

GPIO.output(Relay_Ch2,GPIO.LOW)

print("Channel 2:The Common Contact is access to the Normal Open Contact!")

time.sleep(0.5)

GPIO.output(Relay_Ch2,GPIO.HIGH)

print("Channel 2:The Common Contact is access to the Normal Closed Contact!\n")

time.sleep(0.5)

#Control the Channel 3

GPIO.output(Relay_Ch3,GPIO.LOW)

print("Channel 3:The Common Contact is access to the Normal Open Contact!")

time.sleep(0.5)

GPIO.output(Relay_Ch3,GPIO.HIGH)

print("Channel 3:The Common Contact is access to the Normal Closed Contact!\n")

time.sleep(0.5)

except:

print("except")

GPIO.cleanup()

Though I only connected to a single module, adding three more lights to the 4-channel relay board is as simple as looping the live wire from module to module and sharing a common ground, as illustrated in the diagram below.

At this point, the raspberry pi 4 controls the 4-channel relay module. Closed-loop control for high-powered equipment is made possible by incorporating such code in considerably more complex scripts that consider human input or sensor readings.

Output

Conclusion

Due to human fallibility, it is necessary to install home automation systems to ensure electricity is used efficiently and safely wherever possible. As an intelligent platform, Raspberry Pi enables the interconnection and remote control of many home appliances over a single network infrastructure—specifically, the internet. Because of the convenience provided by these appliances.

Home automation systems are a promising new trend in appliance manufacturing to reduce energy use and human error. Raspberry pi-based automation is cutting-edge and innovative. Automating tasks is easier with a Raspberry Pi.

Tell me if you had trouble understanding it or connecting your relay module to your Raspberry Pi 4 in the comments. The next tutorial will teach you how to connect a GPS module to a Raspberry Pi 4.

Interface Joystick with Raspberry Pi 4 using MCP3008 & LM324

Greetings, and welcome to the next tutorial in our series on programming for the Raspberry Pi 4. The previous tutorial showed us how to connect a 4x4 keypad to a Raspberry Pi 4. In the previous tutorial, we examined the inner workings of the 4-by-4 keyboard; in this one, we'll use the MCP3008 and the LM324 Op-amp IC to connect a joystick to the Raspberry Pi 4. The Joystick is the primary input device for many gaming systems. The Joystick we'll be connecting to the Raspberry Pi today plugs into a USB port, but there are plenty of situations when having access to the Pi's GPIO pins would be useful. We'll review the steps for preparing the circuit for each interface technique and creating a corresponding python script.

So let’s dive in!

Components

The hardware utilized in this instance is a Pi 4 running Raspbian. All the prerequisites for hardware and software have already been covered, and you can find them in the Raspberry Pi Introduction; other than that, we need:

  • 1000µF capacitor

  • MCP3008

  • Joystick Module

  • LM324 Op-amp IC

  • 1KΩ resistor 

  • LED

  • 2.2KΩ resistor 

  • Jumper wires.

Connecting an MCP3008 to a Raspberry Pi joystick

There is a wide variety of joysticks to choose from. In the diagram below, we see a common Joystick module. The Analog Outputs generated by this Joystick module often fluctuate in response to the orientation of the Joystick. Furthermore, we can determine the movement's direction by analyzing these voltage fluctuations with a microcontroller.

Joystick


In my setup, pressing down on the Joystick toggles an on/off state for the button, so you may use any standard GPIO pin to connect yours. I'll connect it in the same way as the potentiometers, though.

You'll need to familiarize yourself with the Serial Peripheral Interface bus protocol and understand how to configure it on the Pi before connecting the analog controllers to the Pi with a little chip that employs SPI as a communication medium. You can find excellent guides on accomplishing this on the Pi 4 Spy website.

The SPI bus will be activated on specific GPIO pins, which will be the first thing you learn. In my experience, Method 1 (opening a config panel in Raspbian and choosing the SPI option) worked flawlessly. Then, you'll need to ensure the MCP3008 chip is wired properly. That will serve as the connection between your Joystick and the Pi. Pulse-width modulation is worth investigating if you want to change your RGB LED (PWM) colours.

Circuit diagram

In case you get stuck, I've included some screenshots and a layout of my setup below.

Input reading

Upon enabling SPI, you should have double-checked that pi-spyder was installed. That is required so that the analog device's input may be read. Setting the LED's colour to correspond with the Joystick's location on the RGB colour wheel may be fun. Let's pretend the X-axis is horizontal over Yellow and the Y-axis is vertical over Orange.

Code

import math

import RPi.GPIO as GPIO

import spidev

# Open SPI bus

spi = spidev.SpiDev()

spi.open(0, 0)

# Define sensor channels (3 to 7 are unused)

mcp3008_switch_channel = 0

mcp3008_x_voltage_channel = 1

mcp3008_y_voltage_channel = 2

# Define RGB channels

red_led = 36

green_led = 31

blue_led = 37

def read_spi_data_channel(channel):

    adc = spi.xfer2([1, (8+channel) << 4, 0])

    return ((adc[1] & 3) << 8) + adc[2]

def convert_coordinates_to_angle(x, y, center_x_pos, center_y_pos):

    dx = x - center_x_pos

    dy = y - center_y_pos

    rads = math.atan2(-dy, dx)

    rads %= 2 * math.pi

    return math.degrees(rads)  

def adjust_angle_for_perspective_of_current_led(angle, led):

    led_peak_angle = 90 if led == 'R' else (210 if led == 'B' else 330)

    return ((angle - led_peak_angle) + 360) % 360

def calculate_next_pwm_duty_cycle_for_led(angle, led):

    angle = adjust_angle_for_perspective_of_current_led(angle, led)

    if 120 < angle < 240:

        return 0

    elif angle <= 120:

        return 100 - (angle * (100 / 120.0))

    else:

        return 100 - ((360 - angle) * (100 / 120.0))

def is_joystick_near_center(x, y, center_x_pos, center_y_pos):

    dx = math.fabs(x - center_x_pos)

    dy = math.fabs(y - center_y_pos)

    return dx < 20 and dy < 20

def main():

    # Center positions when Joystick is at rest

    center_x_pos = 530

    center_y_pos = 504

    GPIO.setmode(GPIO.BOARD)

    GPIO.setup([red_led, green_led, blue_led], GPIO.OUT, initial=GPIO.LOW)

    pwm_r = GPIO.PWM(red_led, 300)

    pwm_g = GPIO.PWM(green_led, 300)

    pwm_b = GPIO.PWM(blue_led, 300)

    pwm_instances = [pwm_r, pwm_g, pwm_b]

    for p in pwm_instances:

        p.start(0)

    try:

        while True:

            # If the joystick switch is pressed down, turn off the LEDs

            switch = read_spi_data_channel(mcp3008_switch_channel)

            if switch == 0:

                for p in pwm_instances:

                    p.ChangeDutyCycle(0)

                continue

            # Read the joystick position data

            x_pos = read_spi_data_channel(mcp3008_x_voltage_channel)

            y_pos = read_spi_data_channel(mcp3008_y_voltage_channel)

            # If Joystick is at rest in the center, turn on all LEDs at max

            if is_joystick_near_center(x_pos, y_pos, center_x_pos, center_y_pos):

                for p in pwm_instances:

                    p.ChangeDutyCycle(100)

                continue

            # Adjust the duty cycle of LEDs based on the joystick position

            angle = convert_coordinates_to_angle(x_pos, y_pos, center_x_pos, center_y_pos)

            pwm_r.ChangeDutyCycle(calculate_next_pwm_duty_cycle_for_led(angle, 'R'))

            pwm_g.ChangeDutyCycle(calculate_next_pwm_duty_cycle_for_led(angle, 'G'))

            pwm_b.ChangeDutyCycle(calculate_next_pwm_duty_cycle_for_led(angle, 'B'))

            # print("Position : ({},{})  --  Angle : {}".format(x_pos, y_pos, round(angle, 2)))

    except KeyboardInterrupt:

        pass

    finally:

        for p in pwm_instances:

            p.stop()

        spi.close()

        GPIO.cleanup()

if __name__ == '__main__':

    main()

So that these methods' input, output, and goals are as apparent as possible, I've put in more effort than normal to comment on the code.

Output

Using OP-amp IC to interface the Joystick to pi 4

Both the X and Y axes are in use. A potentiometer, or "pot," is attached to each axis of the JOY STICK. Rx and Ry are the resulting midpoints of these pots. It follows that Ry and Rx are the movable centers of these kettles. While the Joystick is idle, Rx and Ry serve as voltage dividers.

The voltage at the Rx pin shifts as the Joystick is pushed along the horizontal axis. Similarly, the value at the Ry pin shifts as the device is tilted or turned vertically. The Joystick can be moved in four directions, with two ADC outputs. The voltage at each pin increases or decreases in response to the stick's orientation changes.

As is well-known, Raspberry Pi lacks any built-in Analog Digital Converter hardware. The Pi would be unable to recognize this module if it were attached directly. We shall employ comparators based on operational amplifiers to verify the voltage outputs. These OP-Amps send signals to the Raspberry Pi, and the Pi uses those signals to turn on and off the LEDs. Here, we've implemented a set of four LEDs to represent the four possible Joystick orientations. Please view the accompanying demonstration video.

All 17 GPIO pins have a maximum voltage rating of +3.3V, meaning that any outputs from the Op-amps must be less than that. We needed an op-amp that could operate at 3V, and the LM324 met both requirements. This IC's pins are a good match for the Raspberry Pi's GPIO connectors.

An explanation of operational amplifier circuits.

It has been said that operational amplifiers are the "workhorse" of analog circuits. The LM358 and the LM741 are widely utilized as the most popular varieties of Op-Amp IC. Many functions, such as an amplifier, integrators, differentiators, summers, voltage followers, and more, can be achieved with a single operational amplifier (Op-Amp) by altering the circuitry. Below is a list compiled by Circuit Digest of many Op-amp Circuits, each of which includes a tidy circuit diagram and a practical DIY hardware description to help you learn all about operational amplifiers.

General Operating Conditions of an Operating Amplifier

  • When utilized in Open-loop mode, the Operational Amplifier (or "Op-amp" for short) can be a perfect amplifier with a typical DC gain of over 100,000 or 100dB.

  • In its most fundamental form, an operational amplifier (Op-amp) is a three-terminal device with two inputs and a single output (excluding power connections).

  • The power supply for an operational amplifier can be either a single DC voltage or a pair of supplies, one positive (+V) and one negative (-V).

  • There can be "no current that flows through either of its two inputs" because of the operational amplifier's zero input offset voltage, V1 = V2, and its infinite input impedance, Z = infinity.

  • Also, the output impedance of an operational amplifier is zero (Z = 0).

  • Differential amplifiers, or op-amps, are voltage-sensing amplifiers that magnify the voltage difference between their input terminals by a fixed factor called Gain ( A ).

  • Sometimes called "Open-loop Gain," (A) is a common measure of an amplifier's effectiveness.

  • This open-loop gain can be considerably reduced and controlled by connecting the op-output amp to one of its input terminals to close the loop.

  • There are two common ways to wire operational amplifiers, known as inverting and non-inverting.

LM324 circuit diagram

The LM324 IC includes four OP-AMP comparators to identify Joystick's four possible inputs. Here is the LM324 IC schematic straight from the datasheet.

The following circuit diagram shows the components that make up the Joystick module and the connections that allow it to communicate with the Raspberry Pi. All four comparators within the LM324 are denoted by the U1:A, U1:B, U1:C, and U1:D pins. In the circuit schematic, we have labelled the LM324 IC's comparator pins so that you can easily identify which one goes to which comparator.

Working Explanation

We have OP-AMP1 (or U1:A) and OP-AMP2 (or U1:B) for sensing Joystick motion in the Y axis, and OP-AMP3 (or U1:C) and OP-AMP4 (or U1:D) for sensing Joystick motion in the X axis.

OP-AMP1 picks up on the Y-axis downward movement of the Joystick:

The 2.3V (produced by a voltage divider circuit consisting of 1K and 2.2K) is attached to the negative electrode of comparator U1:A, while the positive terminal is wired to Ry. There is an increase in Ry voltage as the Joystick is moved downward along its Y axis. If the input voltage exceeds 2.3V, the OP-AMP will output +3.3V at the output Pin. In response to the OP-HIGH AMP's logic output, the Raspberry Pi will turn on and off an LED.

Joystick up, Y-axis, is detected by OP-AMP2:

The 1.0V (supplied by a voltage divider circuit consisting of 2.2K and 1K) is connected to the comparator U1: negative B's terminal, while the positive terminal is wired to Ry. As you raise the Joystick's Y axis, the voltage on Ry will drop. The OP-AMP output will go Low when this voltage falls below 1.0V. When the Raspberry Pi sees the LOW logic output from the OP-AMP, it will respond by turning on and off an LED.

With OP-AMP3, X-axis joystick motion to the left is detected:

The comparator U1: negative C's terminal is given 2.3V (1K and 2.2K via a voltage divider circuit), while the positive terminal is linked to Rx. Increasing Rx voltage occurs when the Joystick is moved to the left along its x-axis. If the input voltage exceeds 2.3V, the OP-AMP will output +3.3V at the output Pin. In response to the OP-HIGH AMP's logic output, the Raspberry Pi will turn on and off an LED.

OP-AMP4 recognizes an X-axis joystick movement to the right:

U1:4's negative terminal is given 1.0V (through a voltage divider circuit of 2.2K and 1K), while the positive terminal is linked to Rx. Rx voltage drops as the Joystick is moved to the right along its x-axis. The OP-AMP output will go Low when this voltage falls below 1.0V. When the Raspberry Pi sees the LOW logic output from the OP-AMP, it will respond by turning on and off an LED.

This allows Raspberry Pi to receive input from all four logic that controls the Joystick's four directions. Raspberry Pi uses inputs from these comparators to control the state of the LEDs. Here are the terminal outputs from our Raspberry Pi program, which also prints the Joystick's orientation to the screen.

A Python script is available below. The code is simple, and the comments make it easy to understand.

Complete code

import RPi.GPIO as IO    # calling for the header file, which helps in using GPIOs of PI

import time              # we are calling for time to provide delays in the program

IO.setwarnings(False)    # do not show any warnings

IO.setmode (IO.BCM)      #programming the GPIO by BCM PINs (like PIN29 as GPIO5)

IO.setup(21,IO.OUT)      # initialize GPIO21 as an output      

IO.setup(20,IO.OUT)

IO.setup(16,IO.OUT)

IO.setup(12,IO.OUT)

IO.setup(27,IO.IN)      # initialize GPIO27 as an input

IO.setup(4,IO.IN)

IO.setup(22,IO.IN)

IO.setup(17,IO.IN)

while 1:

    if (IO.input(27) == 0):  #If GPIO 27 goes low toggle LED on 21pin and print RIGHT

        IO.output(21,1)

        time.sleep(0.01)

        IO.output(21,0)

        print ("RIGHT")

    if (IO.input(4) == 1):   #If GPIO 4 goes high toggle LED on 20pin and print LEFT

        IO.output(20,1)

        time.sleep(0.01)

        IO.output(20,0)

        print ("LEFT")

    if (IO.input(22) == 0):  #If GPIO 22 goes low toggle LED on 16pin and print UP

        IO.output(16,1)

        time.sleep(0.01)

        IO.output(16,0)

        print ("UP")

    if (IO.input(17) == 1):  #If GPIO 17 goes high toggle LED on 12pin and print DOW

        IO.output(12,1)

        time.sleep(0.01)

        IO.output(12,0)

        print ("DOWN")           

Output

Conclusion

As we've seen in this guide, the Pi 4 computer lacks an analog input. The only data it can process is digital. Contrast it with the plentiful analog inputs of common microcontrollers like Arduino, AVR, or PIC. Many sensors produce analog outputs; therefore, we need a method to make the Pi analog-friendly. To that end, we have considered two alternatives. Connecting an MCP3008 microcontroller and an LM324 operational amplifier integrated circuit creates a "bridge" between analog and digital signals. If you have any questions regarding the setup or the code, or if you run into any problems, please let me know in the comments, and I'll do my best to help. The next article will teach you how to use a Raspberry Pi 4 to operate a relay board with four independent outputs.

Interface Weight Sensor HX711 with Raspberry Pi 4

Welcome to the next tutorial of our raspberry pi programming tutorial. The previous tutorial showed us how to set up a weather station using the Internet of Things (IoT) on a Raspberry Pi 4. First, we studied how a weather station works on a fundamental level. Then we developed a Python script to collect data from the station. In contrast, we'll construct an automatic gate using a Raspberry Pi, a load cell, and an HX711 weight sensor.

These pressure-sensitive gates are common in shopping centers and showrooms; they open when someone is in the immediate vicinity and close again when the person is out of sight. Like the Automatic Gate, we just made, this one will open in response to weight or pressure and stay that way until the force is removed. If you remove the load from this gate, it will close independently.

In this example, a DC motor is the gate, and a piece of rigid cardboard is the load-bearing surface.

Components

  • Raspberry Pi 4

  • DC motor

  • electric gate or DVD trolley

  • 16x2 LCD

  • Power supply or power bank

  • HX711 Load Cell Amplifier Module 

  • L293D Motor Driver IC

  • Jumper wires

  • Breadboard

Load cell, HX711 Weight Sensor Module, and Nut Bolts

A load cell transducer converts mechanical input (force or pressure) into an electric signal. For example, many strain gauges are fastened to an elastic element (with a highly repeatable deflection waveform) to create a load cell.

The load cell depicted in the figure above features four strain gauges, two on each top and bottom surface.

The elastic element of the resistive load cell illustrated above deflects under the applied force, causing a strain at the stress points. For example, see how the animation below depicts how two strain gauges are under tension while the other two are under compression.

The load cell's metal spring element undergoes elastic deformation due to the weight being measured. Its electrical output scales linearly with the applied force. Load cells contain a strain gauge that bends under stress. Strain gauges produce an electrical signal upon deformation due to a change in their effective resistance. Four strain gauges configured as a Wheatstone bridge make up a typical load cell. While load cells can measure loads as small as 5 kilograms or as much as 100 kilograms, we utilized one that measured up to 40 kilograms.

As the Load cell's output electrical signals are only a few millivolts, an amplifier is required; enter the HX711 Weighing Sensor. The HX711 chip inside the HX711 Weight Sensor Module is a 24 high-precision A/D converter. The HX711 features two channels for analog input, and their gain can be programmed up to 128. The HX711 Module boosts the Load cells' light electrical output. The Arduino uses that amplified, digitally transformed signal to calculate the weight.

Four wires lead from the load cell to the HX711 Load cell Amplifier. Red, black, white, and green/blue are the colors of these four wires. Certain modules may have different wire colors than others. Please find the diagram and connecting information below:

  • RED Wire is connected to E+

  • BLACK Wire is connected to E-

  • WHITE Wire is connected to A-

  • GREEN/BLUE Wire is connected to A+

Channel A or Channel B differential input is chosen by the input multiplexer and fed into the low-noise programmable gain amplifier (PGA). When a 5V supply is connected to the AVDD analog power supply pin, the gain of Channel A can be set to 128 or 64, yielding a full-scale differential input voltage of 20mV or 40mV, respectively. A constant gain of 32 is applied to Channel B. Since the regulator for the analog power used by the Analog-digital converter and the sensor is integrated into the chip, there is no longer any need for a separate supply regulator. The clock input can be set manually. It can come from a crystal or on-chip oscillator that doesn't need anything extra to function. The initialization of digital interfaces is made more accessible by on-chip power-on reset circuitry. The internal registers can be used immediately without any programming. The HX711's pins are used for all of its controls.

Fixing Load Cell with Platform and Base

To make this system function, a Load Cell must be buried beneath the door's threshold to detect the weight of someone standing nearby. But, for the sake of demonstration, we have secured the load cell beneath a sturdy piece of cardboard. This will allow us to test the gate by placing a weight on the cell. The load cell has been securely fastened to the wooden base with nuts and bolts. Several images of the setup can be seen below:

The resistive load cell is based on the piezo-resistive concept. The sensor's resistance changes as a function of the applied force or stress. When an external voltage is introduced, the output voltage will fluctuate due to the change in resistance.

A capacitive load cell measures the load by measuring the voltage required to cause a change in the capacitance of a system. The capacitance of a standard parallel plate capacitor scales inversely with the distance between both the plates and proportionally with the area of overlap between the plates relative to the dielectric between them.

Circuit Explanation

The wiring is simple for this automatic gate, and a diagram is included for reference. The GPIO pins 18, 23, 24, 25, 8, and 7 of the Raspberry Pi are connected to the RS, EN, d4, d5, and d7 pins of the 16x2 LCD. The DT and SCK pins of the HX711 Module are wired to GPIO pins 27 and 17, respectively, on the Raspberry Pi. In contrast, the DATA and SCK pins of the Motor Driver L293D are wired to GPIO pins 12 and 16, respectively. Already stated and depicted in the circuit diagram below are the load cell connections necessary to use the HX711 Module.

Analog Inputs 

A differential input channel connects straight to the differential signal sent by a bridge sensor. Gain settings of 128 or 64 are selectable via programming. Since the sensor output signal is typically somewhat weak, high gains are required. These improvements translate to an input differential voltage of 20mV or 40mV at full scale when a 5V supply is connected to the AVDD port. The gain of the differential input on channel B is always 32. With a 5V supply at the AVDD pin, an input voltage of 80mV is possible.

Working Explanation

Raspberry Pi 4 was used as the central processing unit for this project. First, the pressure near the gate is measured by a load cell, which then sends an analog voltage signal to the HX711 Load sensor Module. Next, the output from the Load cell is amplified and converted to digital form by the HX711, a 24-bit analog-to-digital converter. After that, the Raspberry Pi receives the magnified value. The HX711 output is now converted to a weight value by Raspberry Pi. The motor driver IC L293D is then used by the Raspberry Pi to control the gate based on a comparison with the reference weight. In this case, we're using a DC motor as the gate.

We've set the threshold at 100 grams to ensure that only people weighing more than that are allowed through the gate. Once we've removed the 100 grams or the individual is no longer present, the gate will lock. The standard weighting can be adjusted to fit your needs. The state of the gate can be shown on a 16x2 LCD screen (optional). We have created Python software to automate the entire procedure; the program's source code is available for download, along with a video demonstration.

Programming Explanation

In this case, Python will be used for the coding. We did not use a library to connect the HX711 load sensor to the Raspberry Pi in this project. Our only guide was the HX711 datasheet and the accompanying application notes. Nonetheless, libraries are available for this purpose; by including the library, you can obtain the weight with minimal effort.

Then, the GPIO Library was implemented, with pins for the LCD, HX711, and DC motor defined and various calculation variables being declared.

import RPi.GPIO as gpio

import time

RS =18

EN =23

D4 =24

D5 =25

D6 =8

D7 =7

DT =27

SCK=17

m1=12

m2=1

Following that, the below code will retrieve information from the HX711 Module.

def readCount():

  i=0

  Count=0

  gpio.setup(DT, gpio.OUT)

  gpio.output(DT,1)

  gpio.output(SCK,0)

  gpio.setup(DT, gpio.IN)

  while gpio.input(DT) == 1:

      i=0

  for i in range(24):

        gpio.output(SCK,1)

        Count=Count<<1

        gpio.output(SCK,0)

        #time.sleep(0.001)

        if gpio.input(DT) == 0: 

            Count=Count+1      

  gpio.output(SCK,1)

  Count=Count^0x800000

  gpio.output(SCK,0)

  return Count 

To open or shut the gate, we now compare the HX711 Module's data with a reference weight in the main function.

while 1:

  count= readCount()

  w=0

  w=(count-sample)/106

  print w,"g"

  if w>100:  

    setCursor(0,0)

    lcdprint("Gate Opened ")

    if flag == 0:

      gpio.output(m1, 1)

      gpio.output(m2, 0)

      time.sleep(1.3)

      gpio.output(m1, 0)

      gpio.output(m2, 0)

      time.sleep(1.5)

      flag=1;

      lcdclear()

  elif w<100:

    setCursor(0,0)

    lcdprint("Gate Closed ")

    if flag==1:

      gpio.output(m1, 0)

      gpio.output(m2, 1)

      time.sleep(1.3)

      gpio.output(m1, 0)

      gpio.output(m2, 0)

      time.sleep(2)

      flag=0

  time.sleep(0.5)

In addition, we define several LCD-specific methods, such as begin(), which initializes the display, lcdcmd(ch), which sends commands to the display, lcdwrite(ch), which prints a single character on the display, lcdclear(), which clears the display, and lcdprint(Str), which prints a string. The complete code is included below for your perusal.

As we have shown, an Automated Gate that detects weight using a Raspberry Pi and a load cell is relatively easy to make.

Complete Code

import RPi.GPIO as gpio

import time

RS =18

EN =23

D4 =24

D5 =25

D6 =8

D7 =7

DT =27

SCK=17

m1=12

m2=16

HIGH=1

LOW=0

sample=0

val=0

gpio.setwarnings(False)

gpio.setmode(gpio.BCM)

gpio.setup(RS, gpio.OUT)

gpio.setup(EN, gpio.OUT)

gpio.setup(D4, gpio.OUT)

gpio.setup(D5, gpio.OUT)

gpio.setup(D6, gpio.OUT)

gpio.setup(D7, gpio.OUT)

gpio.setup(m1, gpio.OUT)

gpio.setup(m2, gpio.OUT)

gpio.setup(SCK, gpio.OUT)

gpio.output(m1 , 0)

gpio.output(m2 , 0)

def begin():

  lcdcmd(0x33) 

  lcdcmd(0x32) 

  lcdcmd(0x06)

  lcdcmd(0x0C) 

  lcdcmd(0x28) 

  lcdcmd(0x01) 

  time.sleep(0.0005)

def lcdcmd(ch): 

  gpio.output(RS, 0)

  gpio.output(D4, 0)

  gpio.output(D5, 0)

  gpio.output(D6, 0)

  gpio.output(D7, 0)

  if ch&0x10==0x10:

    gpio.output(D4, 1)

  if ch&0x20==0x20:

    gpio.output(D5, 1)

  if ch&0x40==0x40:

    gpio.output(D6, 1)

  if ch&0x80==0x80:

    gpio.output(D7, 1)

  gpio.output(EN, 1)

  time.sleep(0.005)

  gpio.output(EN, 0)

  # Low bits

  gpio.output(D4, 0)

  gpio.output(D5, 0)

  gpio.output(D6, 0)

  gpio.output(D7, 0)

  if ch&0x01==0x01:

    gpio.output(D4, 1)

  if ch&0x02==0x02:

    gpio.output(D5, 1)

  if ch&0x04==0x04:

    gpio.output(D6, 1)

  if ch&0x08==0x08:

    gpio.output(D7, 1)

  gpio.output(EN, 1)

  time.sleep(0.005)

  gpio.output(EN, 0)

def lcdwrite(ch): 

  gpio.output(RS, 1)

  gpio.output(D4, 0)

  gpio.output(D5, 0)

  gpio.output(D6, 0)

  gpio.output(D7, 0)

  if ch&0x10==0x10:

    gpio.output(D4, 1)

  if ch&0x20==0x20:

    gpio.output(D5, 1)

  if ch&0x40==0x40:

    gpio.output(D6, 1)

  if ch&0x80==0x80:

    gpio.output(D7, 1)

  gpio.output(EN, 1)

  time.sleep(0.005)

  gpio.output(EN, 0)

  # Low bits

  gpio.output(D4, 0)

  gpio.output(D5, 0)

  gpio.output(D6, 0)

  gpio.output(D7, 0)

  if ch&0x01==0x01:

    gpio.output(D4, 1)

  if ch&0x02==0x02:

    gpio.output(D5, 1)

  if ch&0x04==0x04:

    gpio.output(D6, 1)

  if ch&0x08==0x08:

    gpio.output(D7, 1)

  gpio.output(EN, 1)

  time.sleep(0.005)

  gpio.output(EN, 0)

def lcdclear():

  lcdcmd(0x01)

def lcdprint(Str):

  l=0;

  l=len(Str)

  for i in range(l):

    lcdwrite(ord(Str[i]))

def setCursor(x,y):

    if y == 0:

        n=128+x

    elif y == 1:

        n=192+x

    lcdcmd(n)

def readCount():


  i=0

  Count=0

 # print Count

 # time.sleep(0.001)

  gpio.setup(DT, gpio.OUT)

  gpio.output(DT,1)

  gpio.output(SCK,0)

  gpio.setup(DT, gpio.IN)

  while gpio.input(DT) == 1:

      i=0

  for i in range(24):

        gpio.output(SCK,1)

        Count=Count<<1

        gpio.output(SCK,0)

        #time.sleep(0.001)

        if gpio.input(DT) == 0: 

            Count=Count+1

            #print Count

  gpio.output(SCK,1)

  Count=Count^0x800000

  #time.sleep(0.001)

  gpio.output(SCK,0)

  return Count  

begin()

lcdcmd(0x01)

lcdprint(" Automatic Gate ")

lcdcmd(0xc0)

lcdprint("    Using RPI   ")

time.sleep(3)

lcdcmd(0x01)

lcdprint("Circuit Digest")

lcdcmd(0xc0)

lcdprint("Welcomes You")

time.sleep(3)

sample= readCount()

flag=0

lcdclear()

while 1:

  count= readCount()

  w=0

  w=(count-sample)/106

  print w,"g"

  if w>100:  

    setCursor(0,0)

    lcdprint("Gate Opened ")

    if flag == 0:

      gpio.output(m1, 1)

      gpio.output(m2, 0)

      time.sleep(1.3)

      gpio.output(m1, 0)

      gpio.output(m2, 0)

      time.sleep(1.5)

      flag=1;

      lcdclear()

  elif w<100:

    setCursor(0,0)

    lcdprint("Gate Closed ")

    if flag==1:

      gpio.output(m1, 0)

      gpio.output(m2, 1)

      time.sleep(1.3)

      gpio.output(m1, 0)

      gpio.output(m2, 0)

      time.sleep(2)

      flag=0

  time.sleep(0.5)

Conclusion

In conclusion, a weight sensor HX711 and load cell can be easily interfaced with a Raspberry Pi 4 with careful attention to wiring and software configuration. In the right hands, the Raspberry Pi's processing capability can precisely measure mass and analyze the results.

Users must connect the load cell's wires to the HX711 Module and then link the HX711 Module to the Raspberry Pi 4's GPIO pins to interface the weight sensor HX711 and the load cell. After that, Python libraries like "pi-plates" and "HX711" can be used to calibrate and read the sensor values.

Once the sensor is installed, the collected data is used widely, including but not limited to weighing objects, measuring food portions, and automating manufacturing procedures. The Raspberry Pi's processing power and network adapters make it simple to incorporate weight sensing into a wide variety of projects and applications.

For makers, hobbyists, and professionals alike, the HX711 weight sensor and load cell interface with Raspberry Pi 4 provides a robust and versatile platform for measuring and analyzing weight data. The next article will show you how to use Raspberry Pi 4 to create a smart agriculture system based on the Internet of Things.

String Array using Jupyter Notebook in Python
Departments:
  1. Computer Engineering
  2. Computer Science
Codings:
  1. Python
Softwares:
  1. TensorFlow

Hey peeps! Welcome to the Engineering Projects where you are learning the basics of Python in detail. We are working a lot with the arrays as these are important concepts in most of the high-level programming languages till now, the numeric data was used in the arrays but for our practice, we are moving towards the next step where the focus will be on the string data type. The practice is done on the Jupyter notebook and every step is going to be explained well without skipping any concepts but to keep things easy, we are not emphasising unnecessary details and concepts. So, before going deep into the topic, have a look at the list of the contents that will be discussed in this lecture:

  • What are the strings?

  • How do we use the string in arrays?

  • What is the list?

  • How do we extract the characters from a simple string through indexing?

  • How do you relate the string array with the list?

  • How can we get more than one character from a string message without using the array?

  • How do we add more than one message together by using the concatenation?

  • What is the best way to access the elements of the string array through indexing?

  • Can we add more elements of the string array into the already declared array?

  • How do we remove the elements from the string array?

  • What is the relation between the string and character in Python and how do you extract the single alphabets from the string using the list method?

All these concepts will be discussed in detail and will be understood by using the coding in Jupyter Notebook. 

What is the String Array in Python?

Here is a quick revision of the concept we have learned so far in this series but it is important to understand the basic definition so that we may understand the difference between all of some basic data types. The string is the sequenced order of the characters. It means that all the meaningful conversations between people and even this lecture are in the form of string. So, in this way, the array, containing all the elements in the form of the string is called the string array. We define it as:

"The string arrays are the specific type of arrays in which all the elements are in the form of string which means it contains the collection of characters in such a way that every element is a meaningful word."

We use the string in our daily life during the conversation and there is no need to explain more because we have used the string many times in our series of these lectures. 

Getting the Character of String Through Indexing

If we start from the basics then we have to mention that as the string is a collection of different characters, then extracting the characters from the strings it is quite simple and easy. Why we are associating this method with the arrays? It is because the compiler can read all the characters by indexing them one after the other and that is the reason why we can fetch the characters in Python by using the indexing method. So, have a look at the code for doing this simple task:

Code:

#Declaring and printing the string message

str="We are learning Python"

#printing the single character from the message 

print("The string message = ", str)

print("The second character is " ,str[1])

print("The tenth character is ", str[11])

Output:

Getting More than one Character from String

Code:

#Declaring and printing the string message

str="We are learning Python"

#printing the single character from the message 

print("The string message = ", str)

#More than one character

print("The characters from second to ninth index are: " ,str[1:8])

#using only semicolons

print("The first ten index characters are :  " ,str[:10])

#out of the range characters

print("The out of the range characters are :  ", str[:45])

Output:

Here, the following points are to be understood:

  • More than one character can be extracted from the string using the index.

  • The starting and the ending number of the range you want to print are to be given in the index with a separation using the colon. 

  • If the programmer wants to print the elements from the start to a certain number, there is no need to mention the zero, and we can start directly from the colon. 

  •  By the same token, if the colon comes second and then the number is before it, the compiler will print the character at the index starting from the number till the end of the series of the characters.

  • In case, the programmer gives the numbers that are out of range then the compiler, instead of throwing the error, prints the whole string with its intelligent working. 

Adding String Arrays in Jupyter Notebook

We all have been working with the addition of numbers in our tutorials, but today, the good thing about the string array in Python is, the addition of the arrays, even if they have strings in them, is as easy as the other types of “addition processes." The process of concatenation is used for this. We define it as:

"The concatenation is a specific process used for the string to join two or more strings together in a specific manner."

The At this level, there is no need to explain more. Have a look at the following code:

#decalring the arrays with string words

A=["hi", "we", "are", "learning", "Python"]

B=["It", "is", "easy", "with", "theengineering.com"]

#Using the concatenation for the addition

print(A+B)

Output:

Arrays as List of String in Python

In Python, the concept of a string array can be associated with the list because it becomes easy for the programmers to deal with the string as the list has the following feature:

  • These contain the specific order of the elements, and for the string, if we want to have a specific message, the order is important and it makes our task easy. 

  • It allows frequent changes in the elements so that we may change the message according to our requirements.

  • Duplication of the element is possible in the list, and in the passing of the message, we observe the same words in single sentences. 

Similar concepts are being used here that we have seen when we were learning the numerical problems, but this time, it will be interesting to know the difference between the results with the help of shortcodes. 

Accessing the Strings in Different Ways

Once you have declared your string, the extraction of single or multiple strings from the same array is fun. The programmer just has to specify the location, and the element is popped on the output. But there are different ways to do so, and some of them are shown in the code next. 

Code:

#initializing the array containing the name of programming languages

languages=["C++", "C#", "MATLAB", "ASP.NET", "FLutter"]

#printing the arrays using the index in two ways.

print("\bAccessing the data through index: ",languages[3] )

print("\bAccessing the data through negative index: ",languages[-3] )

#getting the whole array of strings through for loop

print("\bPrinting the whole series using loop")

for lan in languages:

    print(lan)

Output:

Updating the String Array

Once the array is made, the good thing is that it can be updated according to the will of the programmer. Let’s say we had an array containing the names of the students in the class; if a new student gets admission or the previous one changes the class, it can be updated easily. In other programming languages, the arrays do not allow the updating of the elements. 

Code:

#initializing the array containing the name of programming languages

languages=["C++", "C#", "MATLAB", "ASP.NET", "Flutter"]

#appending the new element at the end 

languages.append("java")

#getting the whole array of strings through for loop

print("\bPrinting the whole series using loop after appending")

for lan in languages:

    print(lan)

#deleting the element from the array of string

languages.pop(2)

#getting the whole array of strings through for loop

print("\bPrinting the whole series using loop after deleting")

for lan in languages:

    print(lan)

Output:

Hence, the update process is easy to use in arrays. The point that must be cleared here is, the pop function is sued to remove the element from the array and the programmer can not use a string in this place otherwise the compiler will show the error. Only the number of the element can be used in this function, and you must have noticed that it is not the position of the element that we have mentioned here but the index of that particular element. 

Converting String into the List of Characters

In other programming languages, characters are separate data types that contain single alphabets and have their own identity and existence. In this way, there must be a specific way to initialize the characters and the strings. Usually, in languages such as C++ and C#, the ways to declare the string and characters are different. Strings are denoted by double quotation marks, and the characters are defined by using single quotation marks around the alphabet. The point that I want to make here is, in Python, there is no concept of single characters, but the declaration of the words or characters, when single or double quotation marks are used, means the string, no matter if it is a single alphabet or the whole message. 

In case the programmer needs to convert the string into a single alphabet (the data type is still a string), he uses a simple and uncomplicated function to do so. The code and the output of this specific program with an example are given next:

Code to Convert String into Alphabets:

#initialization and printing of the string message.

myMsg = " Python is easy. "

print("The message before conversion= ",myMsg )

#conversion of the string into alphabets.

myMsgList = list(myMsg)

print("The message after conversion= ",myMsgList )

#removing the white spaces from the result.

myMsgList2 = list(myMsg.strip())

print("The message without white spaces =", myMsgList2)


#printing the message without any single space

myMsgList3 = list(myMsg.replace(" ", ""))

print("The message without any single space =", myMsgList3)

Output:

Here, the following points must be known to understand all the operations performed. 

  • The string message is initialized simply, and after that, the programmers can convert it into a list for useful functions. 

  • To convert the whole string message into a single alphabet, the “list” function is used, and the characteristics of the string are converted into the list. Now, you do not have the string on the screen but the list. 

  • In this case, the compiler reads even the blank spaces between the alphabet and shows them in the form of a single character with single quotation marks. 

  • To remove the starting and end spaces, there is a method called "stripping" that eliminates the extra spaces from the message, and as a result, we get only the alphabets with the necessary spaces between them. 

  • Another method called “replace” is used in Python which replaces all the spaces between the message and easily converts the whole message into a series of alphabets with no spaces between them. 

There are other such methods that deal with the string in different ways. For example, the conversion of the string into single words is also possible, but for now, we are not discussing it. This is all for today, and we hope you learned a lot from this lecture. The beginning of this lecture included a very basic introduction to the string, and we saw how we can use strings in arrays. Moreover, using our concepts, we have learned many built-in functions, and with the usage of the string, it was easy to understand the concepts. We have seen the concatenation and other ways through which we can modify the strings according to our requirements. We will talk more about the string in our next lecture; until then, happy coding. 

Types and Operations on Array using NumPy in Python
Departments:
  1. Computer Engineering
  2. Computer Science
Codings:
  1. Python
Softwares:
  1. TensorFlow

Hello students! Welcome to the next episode of NumPy, where we are working more on arrays in detail. NumPy is an important library for Python, and for concepts like integer arrays, it has many useful built-in functions that help programmers a lot. In the previous lecture, the installation and basic functions were discussed and this time, our focus is on the general operations and types of arrays that usually the programmers need during the coding. It is an interesting and basic lecture, and you will learn the following concepts in this lecture:

  • What are some important types of arrays?

  • Why are we using NumPy for arrays?

  • What are zero arrays?

  • What is the random array?

  • How can we use the ones array using NumPy?

  • Is it easy to perform the identity array in Numpy?

  • Practically perform the arithmetic operations in an array.

  • How do we find the maximum and minimum values in the array?

    Important Types of Array with NumPy

    If we talk about arrays, it is a vast concept, and many points are important to discuss. It is one of the reasons why we are using the library of numPy and it becomes super easy to work on the arrays using it. There are different types of arrays that we have learned about in our mathematics classes, and some of them are so important that NumPy has special functions for them so that programmers who want to use them do not have to write the whole code manually, but instead, using some important instructions, the array is formed and used automatically according to the instructions.

    Zeros Array in Python

    Understanding the zeros array is not as difficult as its name implies; it is the array that has all the entries set to zero. In other words, the array does not contain any other value than zero. The size and shape of the array are not restricted by any rules; therefore, any size and shape of the array can be declared as a zero array.

    By the same token, the code for some types of arrays is simple and easy, so here we want to show you how some programmers can add random numbers to their arrays by using this simple instruction. So have a look at the syntax, and then we will use it in the code:

    For the zero arrays:

    myArray =zeros((numbers of rows, numbers of columns))

    For adding more details to your array, you can use the following syntax:

    myArray = np.zeros( shape , dtype , order )

    We are using the zeros array for the first time, therefore, to keep things simple, we will use the first method in our program.

    Random Elements of Arrays:

    random.rand(numbers of rows, numbers of columns)

    Both of these require less effort, but with the help of these built-in functions, the programmers feel the convenience of getting the best result instead of using multiple lines of code to get the required results:

    Code:

    import numpy as NumPy

    #using the zeros method to print the zero array 

    print("\bZero array with two rows and three columns " )

    zeroArray=NumPy.zeros((2,3))

    print(zeroArray)

    #using the random method to print the array 

    print("\bThe random array with two rows and three columns ")

    randomArray=NumPy.random.rand(2,3)

    print(randomArray)

    Output:

    Here, if you have not noticed the syntax, you must see that both of these have similar syntax, but the numbers of brackets are different. If the programmers do not follow the same syntax for each case (for the simple syntax and for the detailed syntax of zero error), then they will face errors.

    Now, here is the task for you, check the other syntax mentioned above about the zeros array and try to find out how you can use the other details in your zeros array. 

    Ones Array using NumPy

    The next program to perform is also easy to understand if you know the previous one discussed above. This time, all the entries in the array are one. It means, no other entry other than 1 is the shape of the array can be rectangular, square, or any other according to the requirement of the programmer. 

    Syntax:

    myArray =ones((numbers of rows, numbers of columns))

    Code:

    #using the ones method to print the ones array 

    print("\bZero array with two rows and three columns " )

    onesArray=NumPy.ones((2,4))

    print(onesArray)

    # Declaring the array as a tuple

    # declaring their data types and printing the results

    onesArray = NumPy.ones((2, 3), dtype=[('x', 'int'), ('y', 'float')])

    print("\bDetailed ones array= ")

    print(onesArray)

    print("\bData type of ones array= ")

    print(onesArray.dtype)

    Output:

    Hence, in this way, we have seen two ways to print our ones array to compare the best method that programmers can use according to their requirements. 

    Identity Array Using NumPy

    The identity array is another important type of matrix or array that is used in multiple instructions, and programmers dealing with numbers must know its formation and applications. We know that the diagonal entries in a matrix or array are the ones that have the same value for row and column. In simple words:

    i=j

    Where,

    i=positions of the row

    j=position of the column

    So, for the identity array, these rules are followed:

    • All the diagonal elements are one.

    • All the elements other than the diagonal are zero. 

    • No other number is used in the diagonal array.

    • The shape of the diagonal matrix is always square, which means the numbers of rows are equal to the number of columns. 

    Now it's time to move towards its code and output.

    Syntax of Identity Array

    myArray=NumPy.identity(integer)

    As you can see, only one number is required for this type of array because it is decided that the numbers of rows and columns are equal. 

    Code for Identity Array

    import numpy as NumPy

    #declaring an identity array with four rows and four columns.

    #printing the simple identity array

    print("\bsimple identity matrix")

    myArray=NumPy.identity(4)

    print(myArray)

    #Multiplying the whole array with three.

    print("\bAfter the multiplication of the identity matrix with three")

    myArray2=3*myArray

    print(myArray2)

    Output

    In this way, we have learned that the multiplication of an array is possible in the code, and it is a simple process just as we do it manually in our mathematical problems. 

    Mathematical Operations on 2D Arrays

    When dealing with the arrays, there are certain points that are pros of choosing this data type to manage our data. One of the most prominent advantages is the mathematical operations that can be performed on the arrays by following simple and uncomplicated syntax. Here is the list of the operations that you are going to observe in just a bit on the arrays:

    Arithmetic Operations on Arrays

    This topic is interesting, and you are going to love it because it is simple to perform and easy to understand but is an important concept in Python, especially when using arrays. We all have been working with addition, subtraction, multiplication, and division since our childhood, and now is the time to use them in arrays. There is no need to explain more, so let’s move towards the code.

    Code for Arithmetic Operations on Array

    import numpy as NumPy

    #Declaring two arrays for the arithmetic operations.

    print("\bElements in arrays")

    A=NumPy.array([[12,45,11,7],[23,8,11,90],[12,55,1,90]])

    print("A= \n", A)

    B=NumPy.array([[76,43,1,90],[43,99,14,11],[12,90,22,55]])

    print("B= \n", B)

    #Performing the arithmetic operations.

    print("\bAddition of arrays \n", A+B)

    print("\bSubtraction of arrays\n", A-B)

    print("\bMultiplication of first array with the second\n", A*B)

    print("\bMultiplication of second array with the first\n", B*A)

    print("\bDivision of first array with the first\n", A/B)

    print("\bDivision of second array with the first\n", B/A)


    Output

    As you can see, we have a long list of outputs, and all the operations that we have discussed are self-explanatory. Here, we have seen that all the arithmetic operations can be done from array to array. Moreover, if you look at both types of multiplication and division, the answers are different, and it makes sense because these arrays do not follow the commutative law when dealing with arrays. Mathematically,

    A*B!=B*A

    Similarly,

    A/B!=B/A

    In addition to this, you must know that scaler arithmetic operations can be performed on the array that means, an integer or the float can be added, multiplied, divide and subtracted from the whole matrix, and the effect of that number will be observed on all the entries of that particular array.

    Maximum and Minimum of An Array

    The next operation in which we are interested in finding the maximum and minimum values in the array. These work great when dealing with image processing and related concepts. These are two different operations, and keep in mind, it seems easy to find the maximum and minimum values in the simple and small arrays, but when talking about the arrays with the order 1000*1000, it becomes almost impossible to find the required value. So without using more time, have a look at the code given next:

    The Syntax for Maximum and Minimum Value

    maximum_value=numPy.max(Name of the array)

    minimu_value=numPy.min(Nmae of the array)

    Code for Maximum and Minimum Value

    import numpy as NumPy

    #Declaring two arrays for the arithmetic operations.

    print("\bElements in arrays")

    A=NumPy.array([[12,45,11,7],[23,8,11,90],[12,55,1,90]])

    print("A= \n", A)

    #Finding the maximum Value

    maximum=NumPy.max(A)

    print("Maximum Value in array = ", maximum)

    #Finding the minimum Value

    minimum=NumPy.min(A)

    print("Minimum Value in array = " ,minimum)


    Code:

    Hence, as you can see, the maximum value occurs more than once in that array, but the compiler only gives us one value. The reason why I am mentioning it is that if NumPy is not used in this case and the programmer does not associate it with the array, the compiler throws the error that there must be another function that has to be used with your particular operation because it takes the array as a tuple. These small details are important to observe because many times, the programmers are stuck into such problems and do not get the reason behind the array. 

    Syntax of Determinant in NumPy


    Determinant=numPy.linalg.det(Name of array)

    Code:

    import numpy as NumPy

    #Declaring two arrays for the arithmetic operations.

    print("\bElements in arrays")

    A=NumPy.array([[12,45,11,7],[23,8,11,90],[12,55,1,90],[11,33,66,1]])

    print("A= \n", A)

    #Getting the determinant of the array

    determinant =NumPy.linalg.det(A)

    print(determinant)

    Output:

    If you are confused with the keyword that we have just used here, let me tell you that linalg is the method in Python that is associated with the determinant of the square array. In other words, as we have used ”random” with the rand function above, there must be the use of linalg with the det function. Moreover, never use these functions with other types of arrays. The determinant can only be used with the square matrix. 

    Hence, it is enough for today. We have seen a lot of information about the arrays in this lecture, and all of these were performed on the NumPy library. At the start, we saw the types of arrays that the programmers used often in the coding. After that, we saw the mathematical operations such as the arithmetic and general operations in the NumPy. We tried our best to use similar arrays for different operations to make the comparison in our minds. All of these were uncomplicated, and throughout this lecture, we revised the basic concepts of the matrices and arrays that we learned years ago during our early education of computers and mathematics.

    Installation and Functions of NumPy in Python
    Departments:
    1. Computer Engineering
    2. Computer Science
    Codings:
    1. Python
    Softwares:
    1. TensorFlow

    Hey, peps! Welcome to the new tutorial on the Jupyter notebook. As we are moving towards a higher level of Python, therefore, it is important to understand other ways of doing the same task. As we read in the previous lecture about 2D arrays, this time it is going to be done with the help of a famous library in Python. This time, you are going to learn different, engaging, and advanced-level concepts that not only help you deal with the 2D array but also the installation and working of the unique library of Python, which is NumPy. This lecture is going to be very useful and interesting, and therefore, we suggest you have a glance at all the goals of this lecture.

    • Getting the introduction to NumPy

    • Successfully installation of NumPy and knowing different methods for it

    • Using the arrays with the help of NumPy

    • Creation, indexing, flattening, and appending of the arrays using NumPy

    • Knowing the different ways in detail to use these methods.

    All of these concepts will be clear to you, and we will move on to more details in the next lecture but for this lecture, it is important to learn the basics.

    What is NumPy?

    NumPy is a fantastic library for dealing with numeric data. You must know that a library in Python is a collection of modules that add functionality to a Python program. Libraries are typically distributed in the form of packages, which can be installed with package managers such as pip. If you remember, at the very first lecture of this course, we installed the packages by using pip. The same is the case with NumPy, and this will be clear in just a bit, but for now, you must know that they said that they could include modules that define functions, classes, and variables, as well as algorithms and other services.

    NumPy, Pandas, matplotlib, and sci-kit-learn are some of the most commonly used Python libraries. They can be used for a variety of tasks, including data analysis and visualization, machine learning, and web development. Python programmers can take advantage of pre-existing code by using libraries, which can save time and effort when compared to writing everything from scratch.

    "NumPy (Numerical Python) is a Python library that adds support for large, multi-dimensional arrays and matrices, as well as a large collection of high-level mathematical functions for operating on these arrays."

    It is a fundamental Python package for scientific computing. The good thing here is, Python provides programmers with several ways to perform the same task so that every person may use the best way according to the requirements and expertise of the programmers. In the previous lecture, a simple method was used to perform the two-dimensional arrays, but you must know that NumPy is the second way to do so, which is the reason why we arranged this lecture.

    Installation of NumPy in Python

    Here comes the action. We are going to work with NumPy, and therefore, the installation process is necessary. The good news is, the programmers do not have to follow the prerequisites when you need to install the NumPy but only Python is enough. So if you are following our previous course, you are good to go with the Numpy. There are two ways to install NumPy:

    1. Installation with the Conda (Advanced level)

    2. Installation with the pip (Beginner’s level)

    Difference between Conda and Pip


    conda

    pip

    It is preferred by professional programmers.

    It is best for the students and learners. 

    It is a cross-language therefore, it can install non-python tools and libraries such as compilers and CUDA.

    It only installs the particular Python on the system. It can not install other libraries rather than Python.

    The source through which the conda installs libraries is its own channel so the resources are owned by the conda itself for the installation. Examples of the channels are defaults and conda-forge. 

    The installation is done from the Python Packaging Index (PyPI). Here it is important to understand that PyPI is the largest collection of packages and therefore, it has many features that create ease for Python programmers. 

    Conda is considered an integrated solution that is used to manage different types of dependencies and environments. It does not need other tools to manage the packages. 

    pip method has to get help from different types of tools to manage and arrange the dependencies and packages.

    Installation of NumPy Using Conda

    Installation with the help of Conda also has different types of methods and for the convenience of all types of users, we are discussing all the basic instructions here.

    The best practice for such installations is to use an environment. It means, instead of using the “install” method, the programmers will create the new environment.

    conda create -n my-env

    Once the environment is created, it's time to activate that particular environment.

    conda activate my-env

    Another option to perform the same option is to use conda-forge. Many professional programmers prefer this method because conda-forge provides a wide range of software packages, and in our case, NumPy is one of them. If you want to install from conda-forge then the following command is needed:

    conda config --env --add channels conda-forge

    The methods given above were a little bit tricky, and if the programmer prefers the simplest way, then they must only write the command given next:

    conda install numpy

    Pip Method for the NumPy

    Now, for the installation process at the beginner level, you have to follow the steps listed next. You have to understand that it is recommended to be at this level because all the requirements of this course are designed according to easy and effective ways to code. Hence, the steps given next are enough for all of you:

    • In the window’s search panel, write the Anaconda prompt.

    • Here, write the following command:

    pip install numpy

    • Wait for the installation and loading of the library on your personal computer. 

    • Now, to check if your NumPy is working well, go to your Jupyter Notebook.

    • For this, fire up your Jupyter Notebook by searching for it in your window applications. 

    • Go to the new Python project and wait for the new tab to be opened in your browser.

    Note: It is essential to notice that every time the programmers want to use Numpy, they have to import it into the code, and that is the first step of every program where the programmer needs to get help from NumPy. 

    Using the Arrays with NumPy

    The typical easy-to-deal-with arrays are similar when we talk about the Jupyter notebook and MATLAB etc. Yet, with the advancement of techniques, better and updated methods have been introduced. The NumPy is a numeric library and to learn its usage, the best way is to deal with the arrays. We hope you know the basics of arrays and their fundamental information; therefore, we are directly starting the practice of arrays. In this way, the students will learn the details of 2D arrays and NumPy side by side. 

    Creating 2D Array Using NumPy

    Creating the array is as simple as what the students have seen in the previous lecture. All the steps are easy, and the comments explain the function of each line.

    #importing the numpy

    import numpy as numPy

    #creating the new array from the imported NumPy library

    myArray = numPy.array([[34,8,12,4],[90,5,12,78]])

    #printing result

    print("The 2D array \n ", myArray)

    The output of this code is as expected:

    Getting Basic Information of Array with NumPy

    If you want to make an array automatically with the minimal information provided by you, then it can be done with the help of NumPy (such as declaring the shape and size of the array). There are other ways to do so, but using NmuPy gives the programmers relief. It is because NumPy has built-in functions; they just have to associate their array with that particular function and get the desired output. 

    #importing the numpy

    import numpy as numPy

    #creating the new array from the imported NumPy library

    #using the reshape and arrange functions

    myArray = numPy.arange(9).reshape(3,3)

    #printing the result

    print("The 2D array \n ", myArray)

    Output:

    Here, the important points to be noticed are

    • The arrange function is used to provide information about the total number of elements in the array. But this must be declared by keeping the shape of the array in mind. 

    • The reshape method has the following syntax:

    reshape(numbers of rows, number of columns)

    • The total number of elements must match the shape so that the compiler may arrange the numbers easily; otherwise, the programmer observes the error. 

    • All of the information is connected with the dot operator in the code. 

    • The values in both these functions are enclosed in parentheses.

    • The arrangement of both functions is important because if the reshape method comes before the arrange method, there will be a long list of errors and the program will not run.

    Indexing and Flattening Using NumPy

    The indeed method is not new to us. We all know that the index always starts at zero. But in the case, we are discussing, one must know that when an array is declared, the index is not for only the elements but for the whole set of the row. 

    Moreover, flatting is a special method in NumPy in which the output of the resultant elements in an array is not shown in the form of brackets and single rows, but the programmer gets the real form of the array that we have used in our mathematics and other cases of the array. If these two are not clear to you now, do not worry because after looking at the code given next, all things will be clear.

    #importing the numpy library

    import numpy as numPy

    #declaring my array

    myArray=numPy.array([[12,56,33,90],[3,89,12,45],[34,89,12,90],[56,12,9,221]])

    #using the flatten function

    output=myArray.flatten()

    print("The array is now = ", output)

    #using the index method to get the third-row

    a=myArray[2]

    print("The third row= ", a)

    The output of this program is given next:

    Hence, in this way, we have learned two functions in one code. Here you must know that there are many simple and important concepts about arrays. If we start discussing them in separate codes, then it will become boring and lengthy to learn the small functions and methods. 

    Appending the Elements in Array 

    Once the array is declared, the elements can then be modified. This concept is not applicable to other programming languages, such as C++. Yet, Python gives us this convenience, which is useful for programmers. The appending method is simple and easy, and this code will justify this:

    #importing the numpy library

    import numpy as numPy

    #declaring my array

    myArray=numPy.array([[12,56],[3,89],[34,89],[56,12]])

    print("\bThe array before appending  \n", myArray )

    #declaring the second array to be appended

    myArray2=numPy.array([[23,89],[12,90],[78,9],[78,11]])

    #appending the second array with the first one and printing the result

    print("\bThe result of two matrices \n ", numPy.append(myArray,myArray2,axis=1))

    Hence, both of these arrays are merged by simply appending them to each other. Moreover, the “axis=1” instruction tells the compiler that the rows of both of these arrays are to be joined in the respective manner; otherwise, the whole array is fixed after the second one. You should check it on yourself.

    Consequently, we have learned a lot today. From the introduction of NumPy to the installation of this library, all the steps were discussed here in detail. Moreover, this library was tested by using the array in different ways, such as creating, changing the dimensions, indexing, flattening, and appending the elements. All of these concepts were discussed thoroughly, and there are many more operations on the arrays. Hence, stay with us for more details in the next lecture.

    Syed Zain Nasir

    I am Syed Zain Nasir, the founder of <a href=https://www.TheEngineeringProjects.com/>The Engineering Projects</a> (TEP). I am a programmer since 2009 before that I just search things, make small projects and now I am sharing my knowledge through this platform.I also work as a freelancer and did many projects related to programming and electrical circuitry. <a href=https://plus.google.com/+SyedZainNasir/>My Google Profile+</a>

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    Syed Zain Nasir
    2 days ago