Access Linux Server of Arduino YUN with Putty
In today's post we are gonna see how to connect Arduino YUN with Putty and access the files on Linux OS in Arduino YUN. In my last post Getting Started With Arduino YUN, I have explained in detail about basics of Arduino YUN. I am recall few important things here. Arduino YUN is a very powerful board with two processors on it. One is Arduino microcontroller used to control the output / input pins. The other processor is named as Atheros and it has Linus operating system on it, so one can easily run python scripts on it and can do any server or client side coding in it.
So, today we are gonna see ow to access this Linux operating system of Arduino YUN using Putty software in Windows. Putty is a third party software used for accessing serial terminal, perform telnet or SSH communication etc. So using this software we can easily access the Linux OS on Arduino YUN. So let's have a look how we are gonna do this.
Access Linux Server of Arduino YUN with Putty
- First of all, download the putty software. Its a free software and you can download it quite easily using google.
- After downloading the software, open it and you will have a screen similar to below image:
- Now first of all select the SSH, which is shown in above figure by # 2, then give the IP address of your arduino YUN and Port will remain 22. If you don't know how to get the IP address of Arduino YUN then read Getting Started With Arduino YUN.
- After adding this information, click on the Open button and for the first time, it will show a window similar to below image, simply click on YES.
- This above Window will appear only when you are using putty for the first time, it won't appear afterwards.
- After clicking YES, the below Window will open up asking for Login as:
- When it asks for login, give log in as "root" and the default password is "arduino".
Note:
- If you have changed the password in first tutorial Getting Started With Arduino YUN, then give that password now.
- When you will be typing the password, nothing will appear on putty that's common so you just simply type the password and hit ENTER.
- Now once you entered the password, it will get connected and you will get the below window.
- Now you are in the root folder of your Arduino YUN Linux operating system, now its just like a command prompt or Linux Command Line.
- Let's write some commands and test it out. Check out the below image:
- In the above figure, you can see the first command sent is "cd .." to go into previous folder.
- After that I send the command "cd mnt/sda1" to access the sd card, its the default folder for sd card.
- Next command I sent is "ls", it will show all the files or folder present in the sd card. Currently I have just one folder in my sd card named as Shell.
- After that I updated the opkg package by giving command "opkg update".
- As I am connected with internet on my Arduino YUN sield, so its automatically downloaded and updated and finally I got "Signature check passed".
- Next I installed a new package named as nano. In order to install it I used the command "opkg install nano". Nano is kind of notepad in Linux.
- Now we are gonna write a python script, so I typed "nano TEP.py", and after entering this command the below window will open up.
- In this window, you can write your python script and press Cntrl+X to Exit and it will ask for the save. Hit Y to save and N to No, and when you press Y then it will be saved.
- Let's check it out whether its saved or not, and in order to do so we have to again send the same command "ls" and it will give us the folders and files as shown below:
- You can see now we have TEP.py as well along with Shell folder.
- So, today we have seen how to connect Arduino YUN with putty and access the Linux side of YUN. Afterwards we tested few commands and also check how to write a python code in YUN.
That's all for today, in the coming post of Arduino YUN I will show you how to connect Arduino YUN automatically with Wifi using python scripts. Till then take care and have fun. :)
How to use LDR Sensor in Proteus
In today's post, I am gonna share how to use LDR sensor in Proteus. Proteus, as we all know, is a very handy software and is used for circuit and PCB designing. It is also used for circuit and programming testing. It is normally used by engineers in their projects and contains a vast list of built-in components. I have posted a lot of tutorials on Proteus and I have got quite a positive feedback from the reader about these tutorials. So, I thought to share another component in Proteus which is quite hidden and I haven't seen much posts on it available online.
So, in today's post, first I am gonna explain what is LDR sensor? and we will see where it is used and how it is used. After that I will design a simple circuit in Proteus in which I will turn control a LED using LDR sensor andwill make it ON and OFF. So, as usual let's start from the beginning so that the newcomers could also get benefit from it.
What is LDR Sensor?
- LDR is an abbreviation of Light dependent resistor. It is also known as photoresistor or photocell.
- Its symbol is shown in the below figure:
- LDR Sensor is used for the detection of light, internally it has a resistance which is sensitive to light as shown in the symbol.
- Whenever light falls on the LDR sensor, its resistance start decreasing and when it comes to dark then its resistance start increasing. Using the value of resistance one can easily detect whether there's light or not.
- It is normally used in light activated switches.For instance, you have seen the automatic street lights, which go ON when its night and automatically go OFF when its day time. In those street lights, LDR sensors are used.
Working of LDR Sensor
- As I explained above, it has an internaal resistance which is very sensitive to light intensity and varies according to it.
- So, one thing is quite clear that LDR sensor is an analog sensor. It gives us different values depending on the light intensity falling on it.
- Let's have a look on the simplest circuit of LDR sensor, which is shown in the below figure:
- Now if you check the above image you can see we have placed a resistor in series with the LDR sensor and have applied a voltage source across them.
- Now when the light will fall on the LDR sensor, its resistance will go LOW and in return the voltage across the LDR will also go LOW and as the LDR will come in dark, the resistance will go HIGH and in return the voltage will also go HIGH.
- Its the simplest working phenomena of LDR sensor. Now if you are using the LDR sensor with some microcontroller then what you need to do is simply give this intermediate connection of resistor and LDR to microcontroller.
Circuit Designing of LDR Sensor in Proteus
- Now we know the basics of LDR sensor and have also seen how it works so now let's design its circuit in Proteus.
- There are two types of LDR sensors available in Proteus which are exactly the same in functioning but are different in operating. Both are shown in the below figure:
- The first one has a digital display along with it on which the voltage value is displayed while the second one a bit more animated and has a torch with it, so when you press the up arrow the torch will come closer and in other words the light is falling on the LDR and when you press the down arrow the the torch will go away and your LDR is in dark now.
- Both of these states are shown in below figure:
- Now you can see both the states quite clearly, in the first state torch is away so LDR is in dark while in second state, torch is close so LDR is ON.
- So, now let's design their circuit to control a LED with LDR Sensor in Proteus. In order to do so, design this simple circuit in Proteus as shown in below figure:
Note:
- I have also designed this circuit on hardware and tested, it works perfectly as shown in the simulation.
- Its a very simple circuit in which I am using a comparator and then giving output to LED. When the LDR is in dark then the LED will remain OFF and when the LDR will go into light then the LED will turn ON.
- Both of these states are shown in below figure:
- Now you can see when the voltage on the digital display of LDR were LOW then the LED was OFF and when Iincreased the voltage then the LED went ON.
- Now let's check both of these states with the second LDR sensor in Proteus, which are shown in the below figure:
- Again quite obvious, when the torch was away then LDR was in dark and the LED was OFF but in second state when I moved the torch close the LED went ON.
- Here's the Proteus Simulation of LDR sensor attached below, download and play with it. :)
Download LDR Sensor in Proteus Simulation
That's all for today, if you have any problem ask in comments and I will reply them. Take care and have fun !!! :)
Interfacing of Seven Segment with Arduino in Proteus
Hello friends, today we are gonna have a look on how to interface Seven Segment with Arduino in Proteus. In my last post, I have posted an Arduino Library for Seven Segment Display, which is designed by our team and is quite basic in functionality. So, if you haven't checked that post then first of all check that one and download the Arduino Library for Seven Segment Display as I am gonna use that library in today's post. Moreover, in order to run this library you are also gonna need to download Arduino Library for Proteus, using this library you will be able to use Arduino board in Proteus so also read that post and download this library and install it in your Proteus.
Again I am mentioning that its the first library designed by our team so its in basic stages, it has few functions and will only display the numeric on the seven segment display which is normally required. I am planning on adding more examples in the library for future use, which will increase the functionality. Anyways that's a future talk, let's start today's post.
What is Seven Segment Display?
Let's first have a look at what is Seven Segment Display. Seven Segment display is nothing but an electronic device used for displaying the numeric data. It's a complex form of LED matrix and is normally used in clocks, LCD displays, calculators etc where there's a need to display the numeric data. It has total seven leds in it which you can also count from above image and by turning these LEDs ON or OFF we can display any numeric on it. For example, have a look at the below image. In this image I have shown numeric 0 on seven segment. Now in order to do so, I just simply turn OFF the centered LED and turn ON all the corner LEDs and it becomes 0.
How does Seven Segment Work?
Now, let's have look at how it works. So, we have seen that Seven Segment is named seven segment because it has total seven LEDs on it so now what we need to do is to control these seven LEDs, also named as segments, and then we can display any character on it. There are two types of seven segments available in the market and named as:
- Common Cathode
- Common Anode
They both work exactly the same and has only a slight difference. They both has total seven pins and each pin is used to control each led and they have an extra pin which is named as Common Pin. In Common Cathode you have to GND this Common Pin, while in common Anode, you have to give +5V to this Common Pin. Have a look at this below image, we have labelled leds with respect to the pins.
Interfacing of Seven Segment with Arduino in Proteus
- Now we know all about Seven Segment Display and know how it works so let's interface Seven Segment with Arduino in Proteus.
- Now, I am assuming that you have installed the Arduino Library for Proteus and have also installed the Arduino Library for Seven Segment display.
- So, now open your Arduino Software and go to File>Examples>SevenSegment>Counting.
- Open this example, in this example I have added a counter which will start counting from 0 to 9 and once it reached 9 then it will start counting again.
- If you can't find this example then you must be making some mistake in installing the library, anyways the code is shown below.
Note:
- In order to run this example you will need two libraries, the inks are given below to download:
/*
Counting
This Arduino example is for Seven Segent display.
It will start the counter from 0 and will end up at 9
and will start again from 0.
This example code is in the public domain.
Created by Syed Zain Nasir at 14 March 2015.
You can get the explanation and latest version of this library at:
http://www.TheEngineeringProjects.com/
*/
#include "SevenSegment.h"
SevenSegment tep = SevenSegment(0,1,2,3,4,5,6);
char arr [10] = {'0','1','2','3','4','5','6','7','8','9'};
int index;
void setup(){
index = 0;
}
void loop(){
tep.display(arr[index++]);
delay(1000);
if(index == 11)
index = 0;
}
- Now open you Proteus Software and design the circuit in it as shown in below figure, I have also attached the file for download at the end.
- Now compile the code and gt the hex file and upload it in your Arduino Properties.
- Now Run the Proteus software, and you will see the seven segment display will start counting, a glimpse of it is shown in the below figure:
- Below is attached the Proteus file and the hex file for the counting example which you simply start and run but again I suggest that you should design it by yourself so that you get something out of it.
Download Proteus Simulation of Seven Segment with Arduino
- One last thing, any kind of contribution to this library from the readers is highly appreciated, design your projects and share codes with us and we will post them on our blog for other readers to get knowledge as knowledge is all about sharing.
That's all for today, hope it will help you in some way. Take care and have fun. :)
Arduino Library for Seven Segment Display
In today's post, I am gonna share a new Arduino Library for Seven Segment Display. In my recent project, I got a chance to work on seven segment displays, I have worked on them using PIC microcontroller but haven't got a chance to use them with Arduino. So, now as usual when I started working on them, I started searching for Arduino Library but I kind of got disappointed after getting quite heavy libraries for seven segments, and after a lot of search I thought of designing my own Arduino library for seven segment display, which I am gonna share in this post. :)
It's not very advanced library as we know seven segment displays are not too complex, so its quite simple and using it you can quite easily display any numerical digit on the seven segment display. Moreover, I have also included an example with the library which will start the counter from zero on seven segment display and keep on incrementing till 9 and after that it will start again from zero. Moreover, I have also posted the example about Interfacing of Seven Segment Display with Arduino in Proteus using this library, it will help you in better understanding of How this library works. You can download the working Proteus Simulation as well as hex file from that post.
Download Arduino Library for Seven Segment Display
- As I stated earlier, its a very simple Arduino Library for Seven Segment Display and it will only print the numeric on seven segment display, but I will work on it in future and will update it by adding more features in it.
- So, first of all click the below button to download the Arduino library for seven segment display.
Download Arduino Library for Seven Segment Display
- After downloading the library, place it in the libraries folder of your Arduino software.
- Now close your Arduino software and open it again.
- Go to File and then Examples and you will find SevenSegment in it and it will have an example which is named as Counting.
Functions in Arduino Library for Seven Segment Display
- I have added quite few function in it which are very basic and are very easy to use.
- The first function I have used is:
SevenSegment(int a,int b,int c,int d,int e,int f,int g);
- In this function, you need to give the pins of Arduino with which you are attaching your seven segment display. It will called as shown below:
SevenSegment tep = SevenSegment(0,1,2,3,4,5,6);
- Now tep is our seven segment object and we are gonna use it in rest of the example.
- The next function used in this arduino library for seven segment display is:
display(char c);
- This function will display the numeric on seven segment display which you will provide it.
- Moreover, it will automatically clear the screen before displaying any new character on the seven segment.
- It is called in the example as shown below:
tep.display('1');
That's all for today, in this next post you can download the example of how to
Interface Seven Segment Display Using Arduino in Proteus, it will help you in understanding of this library in detail.
Temperature Sensor 18B20 with Arduino
Hello everyone, in today's post we are gonna have a look at how to interface temperature sensor Dallas 18B20 with Arduino. There are many temperature sensors available in market like LM35, DHT11 etc but personally I like Dallas18B20 most of all, as it gives the most accurate result up to four decimal points. It operates on single wire and sends all data through this wire. Another advantage of this wire is you can interface multiple sensors with a single data line. You should also have a look at How to use 18B20 in Proteus ISIS.
In today's post, we are gonna get value from this sensor and then print it over the Serial Terminal as well as LCD. We will get the values in degree centigrade. Its not much difficult to interface 18B20 with arduino and also an Arduino library is also availble, using which you can quite easily interface 18B20 with Arduino. Let's get started with interfacing of 18B20 with Arduino.
Note:
Interfacing of Temperature Sensor 18B20 with Arduino
- As I explained earlier, it works on single wire and hence we are gonna need 1-wire library for Arduino along with 18B20 arduino library.
- Download both of these libraries by clicking on the below buttons:
Download One Wire Library Download Dallas Temperature Library
- After downloading the library, place it in the libraries folder of your Arduino Software.
- Now restart your Arduino software and you will find the Arduino folder in the Examples section.
- Next we need to interface our sensor 18B20 with Arduino so design your circuit as shown in below figure:
- So, connect the sensor 18B20 with Arduino as shown in the above figure, connections are quite simple and are as follows:
- Pin # 1 of 18B20 with GND
- Pin # 2 of 18B20 with Pin # 2 of Arduino.
- Pin # 3 of 18B20 with GND of Arduino.
- Add a pull up resistor of 4.7k ohm at pin # 2 of 18B20.
- Here's the images of hardware, we designed for this project, its a 20 x 4 lcd we have used:
- Below image shows the small 18B20 sensor, used in this project, it looks small but very efficient.
- Here's the image showing the complete project:
- Now, copy below code and upload it in your Arduino board and open your serial terminal.
#include <OneWire.h>
#include <DallasTemperature.h>
#include <LiquidCrystal.h>
#define ONE_WIRE_BUS 2
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
LiquidCrystal lcd(12, 11, 7, 6, 5, 4);
void setup(void)
{
Serial.begin(9600);
Serial.println("Welcome to TEP !!!");
Serial.println("www.TheEngineeringProjects.com");
Serial.println();
sensors.begin();
lcd.begin(20, 4);
lcd.setCursor(5,0);
lcd.print("Welcome to:");
lcd.setCursor(1,2);
lcd.print("www.TheEngineering");
lcd.setCursor(4,3);
lcd.print("Projects.com");
delay(5000);
}
void loop(void)
{
sensors.requestTemperatures();
Serial.print("Temperature : ");
Serial.println(sensors.getTempCByIndex(0));
//lcd.clear();
lcd.setCursor(0,0);
lcd.print("Temperature: ");
lcd.print(sensors.getTempCByIndex(0));
lcd.print("C");
delay(1000);
}
- After uploading the code, when I start the project, it started showing the temperature values as shown below:
- As you can see, its giving the temperature of my room which is 23.56 degree centigrade.
- I have also designed a video for more demonstration which is given below:
- It's quite a simple code and is self explanatory but still if you need help ask in comments and I will help you out.
Interfacing of Multiple Ultrasonic Sensor With Arduino
Hello friends, hope you are having fun and enjoying life. Today, I am gonna post about interfacing of multiple Ultrasonic sensor with Arduino. In the previous post, we have seen Interfacing of Ultrasonic Sensor With Arduino and in this post I have interfaced single ultrasonic sensor but in projects especially related to robotics, we have to interface multiple ultrasonic sensors. For example you have an obstacle detection robot, now in order to detect obstacle in front of robot you have to place once sensor on the front side but now you can't detect any object present on left or right side of your robot, so you have to place two sensors one on the left side of robot and one on the right side so in this project you need to use total three ultrasonic sensors, one on the front, one on left and one on right side of robot. Similarly, in another project I have to move the robot in a maze having walls on the side of robots, and my task was to move the robot straight within these walls without hitting the walls. In that case, I also used two ultrasonic sensors on both sides of robot and then applied PID algorithm in order to avoid hitting the walls. So, in short its a common practice to use multiple ultrasonic sensor with Arduino and today we are gonna have a look at how to do it.
I have posted about the basics of Ultrasonic sensor and how it works in my previous post so I am not gonna go into that detail. If you haven't read it then I recommend that you should first read Interfacing of Ultrasonic sensor with Arduino. Now, let's get started with Interfacing of multiple ultrasonic sensor with arduino, which isn't that difficult. :)
Note:
- Other Proteus Libraries are as follows:
- I have also posted more examples on Ultrasonic Sensor Simulation in Proteus, have a look at them and you will get complete understanding of this sensor.
- Moreover, for hardware implementation of Ultrasonic Sensor with Arduino, check below posts:
Interfacing of Multiple Ultrasonic Sensor With Arduino
- Let me first summarize the working of ultrasonic sensor again. With ultrasonic sensor, what we need to do is to generate a trigger signal on its trigger pin for around 10 microsecond.
- As soon as the ultrasonic sensor gets this trigger signal, it sends out an ultrasonic signal.
- This ultrasonic signal then hits something and bounced back.
- Now, in order to check this bouncing signal, we have to read the Echo pin and check for how long it remains HIGH, and on the basis of this duration we calculate our distance with the object.
- This is the process for single ultrasonic sensor and when we are using multiple ultrasonic sensors, what we need to do is simply repeat the whole procedure for all the sensors one by one.
- First of all, we will generate the trigger pulse for first sensor and the read its echo pin and get the distance, then we generate the trigger pulse for second sensor and read its echo pin and so on for the third.
- So, here I am gonna use three ultrasonic sensor and the circuit diagram is shown below:
- I have tried my best while designing this image to make it simple but as there are too much wires so it has become a little complex.
- I am pointing out the pin configuration here so it will be easy for you to interface your sensors with arduino. The pin configuration is as follows:
- Vcc of all sensors will go into +5V of Arduino.
- GND of all sensors will go into GND of Arduino.
- Trig Pin of first sensor into Pin # 3 of Arduino.
- Echho Pin of first sensor into Pin # 2 of Arduino.
- Trig Pin of second sensor into Pin # 4 of Arduino.
- Echo pin of second sensor into Pin # 5 of Arduino.
- Trig Pin of third sensor into Pin # 7 of Arduino.
- Echo pin of third sensor into Pin # 8 of Arduino.
- After connecting the pins as discussed above, now copy the below code and upload it in your arduino board.
- After uploading the code in your arduino, open the Serial Terminal of Arduino software and you will start receiving the distances for all the three sensors.
#define trigPin1 3
#define echoPin1 2
#define trigPin2 4
#define echoPin2 5
#define trigPin3 7
#define echoPin3 8
long duration, distance, RightSensor,BackSensor,FrontSensor,LeftSensor;
void setup()
{
Serial.begin (9600);
pinMode(trigPin1, OUTPUT);
pinMode(echoPin1, INPUT);
pinMode(trigPin2, OUTPUT);
pinMode(echoPin2, INPUT);
pinMode(trigPin3, OUTPUT);
pinMode(echoPin3, INPUT);
}
void loop() {
SonarSensor(trigPin1, echoPin1);
RightSensor = distance;
SonarSensor(trigPin2, echoPin2);
LeftSensor = distance;
SonarSensor(trigPin3, echoPin3);
FrontSensor = distance;
Serial.print(LeftSensor);
Serial.print(" - ");
Serial.print(FrontSensor);
Serial.print(" - ");
Serial.println(RightSensor);
}
void SonarSensor(int trigPin,int echoPin)
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;
}
- The code is quite similar to the one we used while interfacing single ultrasonic sensor with arduino, the only thing we changed here is the repetition.
- Before, we were using the same function SonarSensor() but calling it only once for our single sensor interfaced with arduino but now we are calling it three times for all the three sensors.
- Its kind of a generic code, you can interface more sensors with it if you want and what you need to do is only calling this function for the next interfaced sensor.
That's all for today, I think we have posted a lot on the ultrasonic sensor so I am not gonna post any more tutorial on this sensor and now I will start writing on some other sensor. You should also have a look at
Arduino Projects for Beginners. Thanks for reading and share it with your friends and help us grow. :)
Interfacing of Ultrasonic Sensor With Arduino
Today, we are gonna have a look on How to Interface Ultrasonic Sensor with Arduino. Few days ago, I have posted a complete tutorial on How to Use Ultrasonic Sensor Library in Proteus and later I have posted different examples on How to Simulate Ultrasonic Sensor in Proteus. Those posts were about Proteus Simulations and weren't about hardware interfacing, so I thought today let's interface it in hardware.
Simulation is a good starting point for projects but they are really far away from real world. It happened to me a lot of times that my simulations are working perfectly fine but when I design the same circuit in hardware then it says no I am not gonna work. :) So, the bottom line is never trust simulations, unless you properly test it on hardware. So, today I am gonna interface an Ultrasonic sensor with arduino and will check its output on the Arduino Serial Terminal.
1. Introduction to Ultrasonic Sensor
- "Ultrasonic Sensor HC-SR04 is a simple sensor which emits Ultrasonic Radiations from its transmitter and is used for measuring the distance between sensor itself and any obstacle in front of it. The sensor has a transmitter and a receiver on it."
- This sensor consists of four pins, which are:
- Vcc (+5V) : You need to provide +5V at this Ultrasonic Sensor HC-SR04 Pin.
- Trig (Trigger) : It's a trigger Pin where we need to provide a trigger after which this sensor emits ultrasonic waves.
- Echo : When Ultrasonic waves emitted y the transmitter, hit some object then they are bounced back and are received by the receiver and at that moment this echo Pin goes HIGH.
- GND : We need to provide ground to this PIN of HC-SR04 Ultrasonic Sensor.
Note:
- If you haven't bought your components yet for this project, then you can buy them from these reliable sources:
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- Trigger pin is an output pin while the Echo pin is an input pin, we will discuss them in Working section in detail.
- Moreover, it requires +5V to start operating.
- It is normally used to detect objects in front of it or to measure the distance between different objects.
2. Working of Ultrasonic Sensor
- Its working is quite simple, as discussed above, it has a trigger and an echo pin.
- A signal of +5V is sent over to Trigger pin for around 10 microseconds in order to trigger the sensor.
- When ultrasonic sensor gets a trigger signal on its trigger pin then it emits an ultrasonic signal from the transmitter.
- This ultrasonic senor, then goes out and reflected back after hitting some object in front.
- This reflected ultrasonic signal is then captured by the receiver of ultrasonic sensor.
- As the sensor gets this reflected signal, it automatically make the Echo pin high.
- The time for which the Echo pin will remain HIGH, depends on the reflected signal.
- What we need to do is, we need to read this time for which the echo pin is high, which we are gonna do in our next section.
- So, let's have a look at Ultrasonic Sensor Arduino Interfacing.
3. Interfacing of Ultrasonic Sensor With Arduino
- Now we have seen the working of Ultrasonic sensor, so we have some idea what we need to do in order to get the values from it. Let's now have a look at Ultrasonic Sensor Arduino Interfacing.
- First of all, we need to generate a signal of 10 microsecond and then send it over to trigger pin.
- After sending the trigger pin we then need to read the echo pin and wait for it to get HIGH.
- Once it got HIGH then we need to count the time for how long it remained HIGH.
- On the basis of this time, we are gonna calculate the distance of the object from the ultrasonic sensor.
- So, first of all, interface your ultrasonic sensor with arduino as shown in below figure:
- Now, use the below code and upload it your arduino board. After uploading the code, open your serial terminal of Arduino software and you will start receiving the values.
#define trigPin1 8
#define echoPin1 7
long duration, distance, UltraSensor;
void setup()
{
Serial.begin (9600);
pinMode(trigPin1, OUTPUT);
pinMode(echoPin1, INPUT);
}
void loop() {
SonarSensor(trigPin1, echoPin1);
UltraSensor = distance;
Serial.println(UltraSensor);
}
void SonarSensor(int trigPin,int echoPin)
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;
delay(100);
}
- Now if you check in the SonarSensor() function, we are generating a pulse of 10 microsecond and sending it to trigPin, which is the trigger pin of our ultrasonic sensor.
- After sending this pulse weare using a funcion pulseIn() , its a builtin arduinofunction and is used to check for how long the echoPin remains HIGH.
- This value is further saved in the duration value and after that we have divided this duration by 2 because the pulse is first sent and then received so in actual it covers double distance, so we need to divide it by 2 in order to get distance between object and the sensor.
- Furthermore, it is again divided by 29.1, which is basically the speed of ultrasonic sound and finally we saved it in a variable named distance which is now in centimeters.
- After uploading the sketch in Arduino, you need to open the Serial Terminal and you will start receiving the values of distance.
That's all for today. I hope you have enjoyed this Interfacing of Ultrasonic Sensor with Arduino. It wasn't that difficult, in our coming post we are gonna
Interface Multiple ultrasonic sensors with Arduino and will get their values on the serial terminal. Till then Take care and have fun !!! :)
Receive SMS with AT Commands using Sim900 and Arduino
Update: I have updated the code and removed the bug. Thanks for informing. Now this code will work perfectly.
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Hello friends, hope you all are fine and having good health. Today, as the name suggests, I am gonna post on how to Receive SMS with AT Commands using Sim900 and Arduino. I have already posted a tutorial on How to Send SMS with Arduino UNO and Sim900, so now we are gonna check the opposite. Sending SMS is quite easy, you just need to write some AT commands and write the message you wanna send and hit the Cntrl + Z and it will be sent. But receiving a text message on your SIM900 shield is a bit difficult because now you need to place a check when user will send a message. So, ideally whenever anyone send a message to your SIM900 module, you should get notified. Today, we are gonna cover this how to receive SMS with AT Commands in detail.
Now, after you get notified, there's a need to read the message as well and also who has sent this message. So, we are also gonna cover it today. So, first of all we will place a check that whenever someone sends a message to our SIM900 module, we get notified and after that we will extract the message and the mobile number of sender. We have designed this code after a lot of effort that's why this code isn't free but we haven't placed a very small amount of $20 so that engineering students can also buy it easily. We can also interface our GSM board with other microcontrollers like PIC Microcontroller as well as 8051 Microcontroller. I have also posted tutorial on How to Receive SMS with SIM900 & PIC Microcontroller and How to Send SMS with PIC Microcontroller so if you are working on PIC Microcontroller then you must give it a look. So, let's get started with How to receive SMS with AT Commands using SIM900 and Arduino.
You must also check GSM Library for Proteus, using this library you can easily simulate your GSM module in Proteus ISIS. Moreover, also have a look at Send SMS with Sim900D in Proteus ISIS in which I have designed a simulation of sms sending in Proteus ISIS.
Receive SMS with AT Commands using Sim900 and Arduino
- There are many GSM modules available in the market so it doesn't matter which one you are using unless its having SIM900 module in it.
- I have explained in my previous post that all GSM modules work on AT commands, so here first of all we are gonna have a look on AT commands we are gonna use for receiving the SMS.
- ATE0 - IT is used to turn off the Echo of GSM shield.
- AT - Just to check that your GSM module is working fine.
- AT + CMGF = 1 - This command will convert the message style to text. In other words we are telling our shield that we are expecting a text message.
- AT+CNMI=1,2,0,0,0 - This command will alert our GSM shield and now whenever it will receive message, it will automatically send an alert on the serial port.
- We are gonna use these four commands in our code and we will be able to receive text message on the GSM shield.
- Remember we have to put Enter after each of the above AT commands in order to execute it.
- Below is the first phase of the code and as you can see in this code we are simply sending these four commands serially from arduino to GSM shield.
- These are two functions I have shown below, the first function is Config() which is simply sending the commands via serially and then the Response() function which is called after every AT command and is receiving the response of that AT command.
- So, here's the partial code for How to Receive SMS with AT Commands using Sim900 and Arduino.
void Config()
{
delay(1000);
Serial.print("ATE0r");
Response();
Serial.print("ATr");
Response();
Serial.print("AT+CMGF=1r");
Response();
Serial.print("AT+CNMI=1,2,0,0,0r");
Response();
}
void Response()
{
int count = 0;
Serial.println();
while(1)
{
if(Serial.available())
{
char data =Serial.read();
if(data == 'K'){Serial.println("OK");break;}
if(data == 'R'){Serial.println("GSM Not Working");break;}
}
count++;
delay(10);
if(count == 1000){Serial.println("GSM not Found");break;}
}
}
- The response of these commands is shown below on the Serial Monitor of Arduino.
- For each AT command, we get a response "OK" from the GSM shield.
- Now, I know that I have sent all these four AT commands and my GSM shield is ready to receive the text messages and will inform me.
- So, when you send a message to your GSM shield, it will give a notification as shown in the below figure:
- Each message received by SIM900 module is start with "+CMT" and after that it has the mobile number of the sender and at the end lies the body of the message, which in our message is "www.TheEngineeringProjects.com"
- So now let's extract this mobile number and the text body from this CMT string.
Getting the SMS Text & Sender Mobile Number
- Till now we have learnt How to Receive SMS with AT Commands using Sim900 and Arduino and send you notification over the serial monitor.
- Now we have to place some checks in our code so that we could be able to get the required data out of this string.
- In order to do so, I am gonna first save this CMT string into an array, which I named as RcvdMsg[index].
- But before saving the data into this string, first I need to make sure that I am actually getting the requried string, that's aso possible that I am receving some garbage values.
- So, I placed a check first, which is checking for these four characters "+CMT", and when I got these character on my serial terminal I got sure that I have the string ready so I made the index = 0 and starting receving the string.
- Next thing I need to do is make sure that I have got the complete string, that was really a tricky part as there's no end character in the string.
- So, I used "n" null character for that. If you check the string then you can see that we are getting two null characters in complete string.
- I placed this check that when I get 2 null characters means I have got the complete string so I stopped receving the string.
- After that I simply count the charaters, in my string the sender mobile number is at posting 4 to 16 so I made a loop and save it in another array. and similarly did for the message text.
- Now when I send message after uploading this final code into my Arduino board, I get the below result on my Serial Monitor.
- Isn't it cool :) So, now we have separated the complete text as well as the sender's mobile number from our GSM string and we can use it anywhere we want.
- We can use this mobile number in the previous post code and can reply some text back and can also give a missed call to the user, anything we want. I am gonna post on How to send a call using SIM900 in the next post.
- You can buy the codefor How to Receive SMS with AT Commands using Sim900 and Arduino from our shop by clicking the below button:
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- I have highlighted all the functions in the code.
- As I always say, understand it first and then write on your own and do mistakes so that you learn.
That's all for today. I hope you have enjoyed this project named Receive SMS with AT Commands using Sim900 and Arduino. I will meet you guys in the next post. Till then have fun !!! :)
Black Litterman Approach in MATLAB
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This post is the next part of our previous post Financial Calculations in MATLAB named as Implementation of Black Litterman Approach in MATLAB, so if you haven't read that then you can't understand what's going on here so, its better that you should first have a look at that post. Moreover, as this code is designed after a lot of our team effort so its not free but we have placed a very small cost of $20. So you can buy it easily by clicking on the above button.In the previous post, we have covered five steps in which we first get the financial stock data, then converted it to common currency and after that we calculated the expected returns and covariance matrix and then plot the frontiers with and without risk free rate of 3%. Now in this post, we are gonna calculate the optimal asset allocation, average return after the back test, calculation of alphas and betas of the system and finally the implementation of black-litterman approach. First five steps are explained in the previous tutorial and the next four steps for Implementation of Black Litterman Approach in MATLAB are gonna discuss in this tutorial, which are as follows:
- Step 6: Calculate Optimal Asset Allocation
- Step 7: Average Return after the back test
- Step 8: Calculation of Standard Deviation
- Step 9: Calculate alphas & betas of the system
- Step 10: Implementation of Black Litterman Approach
You may also like to read:
Step 6: Calculate Optimal Asset Allocation
In this part of the problem,I calculated the optimal asset allocation in the different years by choosing a constant required return. I chose the constant required return equal to 0.01 and used the highest_slope_portfolio function and plot the graphs. The code used in MATLAB is shown in the below:
ConsRet=0.010
for w=1:10
[xoptCR(:,w), muoptCR(w), sigoptCR(w)] = highest_slope_portfolio( covmat{1,w}, ConsRet , estReturn(w,:)', stdRet(w,:) );
End
The result for this part is shown in the Figure 3. For a constant required return of 0.01, portfolio turnover for each year has increased approximately by 2%.
Figure: Optimal asset allocation for constant return of 0.01
Step 7: Average Return after the back test
In this part of the assignment, it was asked to perform a back test for the optimized portfolios and calculate the average return and the standard deviation for this portfolio. Average return is the average of expected return for the corresponding year and it is calculated by the below code in MATLAB, where w is varying from 1 to 10 to calculate for all the 10 years.
BTreturn(w,:)=estReturn(w,:)*xoptCR(:,w);
Results obtained after the back test for the optimized portfolios for average return are shown in table3 below:
| Average Return after the back test |
| 1st year |
0.1158 |
| 2nd year |
0.0889 |
| 3rd year |
0.0797 |
| 4th year |
0.0628 |
| 5th year |
-0.0660 |
| 6th year |
-0.4323 |
| 7th year |
-5.1212 |
| 8th year |
-0.6820 |
| 9th year |
0.2891 |
| 10th year |
0.1691 |
Table : Average return after the back test
Step 8: Calculation of Standard Deviation
The standard deviation of the rate of return is a measure of risk. It is defined as the square root of the variance, which in turn is the expected value of the squared deviations from the expected return. The higher the volatility in outcomes, the higher will be the average value of these squared deviations. Therefore, variance and standard deviation measure the uncertainty of outcomes. Symbolically,
Where,
- S = Standard Deviation
- E(r) = Expected return
- p(s) = Probability of each scenario
- r(s) = Holding-price return in each scenario.
- s = number of scenarios.
- n = Maximum number of scenarios.
Matlab code for calculating the standard deviation after the back test is shown below:
BTstd(w,:)=sqrt(stdRet(w,:).^2*(xoptCR(:,w).^2));
The results of standard deviation for the 10 years are as follows:
| Standard Deviation after the back test |
| 1st year |
0.2942 |
| 2nd year |
0.1833 |
| 3rd year |
0.1799 |
| 4th year |
0.1733 |
| 5th year |
0.4026 |
| 6th year |
1.5834 |
| 7th year |
16.1279 |
| 8th year |
2.1722 |
| 9th year |
1.0430 |
| 10th year |
0.4949 |
Step 9: Calculate Alphas & Betas of the system
In this part, it was asked to use a broad stock index for testing and check whether our portfolio is in line with the CAPM prediction:
Hence, first of all I retrieved the historical data for ticker ^FTLC using the function hist_stock_data as I done in the first part of the assignment. The MATLAB code for retrieving the data is shown below:
FTLC= hist_stock_data('01111993','01112013','^FTLC','frequency','m');
LRFTLC=diff(log(FTLC.Close));
After that I calculated the expected return of one unit of each asset based on the model which gave me the total covariance matrix for the single and multi indexed model. Finally, I calculated the alpha and beta for the model. The MATLAB code used for performing these actions is shown below:
for i = 1:7
mdl_si{i} = LinearModel.fit(LRFTLC, logRet(:,i), 'linear');
mdl_ret_s(i) = mdl_si{i}.Coefficients.Estimate(1:2)' * [1; 12*mean(LRFTLC)];
mdl_cov_s(i) = mdl_si{i}.RMSE^2;
alpha_s = [mdl_si{i}.Coefficients.Estimate(1), alpha_s];
beta_s = [mdl_si{i}.Coefficients.Estimate(2), beta_s];
end
As a result, alphas and betas of the system are obtained which are shown in the table below:
| Aplha |
Beta |
| 0.0068 |
0.1748 |
| 0.0057 |
0.0335 |
| 0.0050 |
0.0528 |
| 0.0063 |
0.0552 |
| 0.0030 |
0.0249 |
| 0.0035 |
0.0083 |
| 0.0047 |
0.0289 |
Table: Alpha & beta of the model
Step 10: Implementation of Black Litterman approach
In this part, I have finally implemented the Black Litterman approach on the data available. Black Litterman approach involves the below steps:
Few MATLAB Projects:
- The Covariance Matrix from Historical Data
- Determination of a Baseline Forecast
- Integrating the Manager’s Private Views
- Revised (Posterior) Expectations
- Portfolio Optimization
The code used for implementing the black litterman approach is shown below and the results obtained as a result of Black Litterman approach are shown in the below figure. Risk aversion is take as 1.9 while the precision is 0.3.
gamma = 1.9;
tau = .3;
for w=1:10
ind=[(w-1)*12+1 (w+10)*12];
logRet2=logRet(ind(1):ind(2),:);
for i=1:7
OplogRet(:,i)=logRet2(i,:).*xoptCR(i,w)'*100;
end
covmatOP{1,w}=12*cov(OplogRet);
end
for w=1:10
Opweig(:,w)=xoptCR(:,w);
Pi{w}= gamma *covmatOP{1,w}* Opweig(:,w);
end
figure
for w=1:10
title('BL');
hold on;
bar(Pi{w})
hold on;
end
Figure: Bar graph for Black-Litterman approach
That's all for today, hope it will help you all in some way. If you have any questions then ask in comments and I will try my best to resolve them.
Arduino Lilypad Simulation in Proteus
Yesterday, I have posted a new Arduino Lilypad / Nano Library for Proteus in which we have seen how to add that library into Proteus so that you could be able to use these boards in Proteus. That was quite easy. Today I am gonna post a small project in which we will see how to use that library and produce an Arduino Lilypad simulation in Proteus. In this Arduino Lilypad simulation in Proteus, I am gonna use obviously he Arduino Lilypad board along with few LED lightsand will make them blink. Its also quite easy and you can also download the simulation and the hex file at the end of this project but I would suggest you to do it yourself so that you learn something out of it.
Before starting this project, you must have first integrated the Arduino Lilypad Library as without it you wont be abe to do this project. So, if you haven't downloaded it yet then you should read the previous post Arduino Lilypad / Nano Library for Proteus first. Lets get started with this project.
Arduino Lilypad Simulation in Proteus
- Now I assue that you have already downloaded the Arduino Lilypad Library for Proteus and are ready to use it within Proteus.
- So open Proteus ISIS and get these components from the Proteus components library as shown in below figure:
- After getting these components, draw a circuit in Proteus as shown in the below figure:
- You can clearly see in the above figure, the Arduino Lilypad Simulation in Proteus. After that you need to write a code for Arduino Lilypad so that you could get the hex file for it.
- In this project, I have used three LED lights and make them ON and OFF using the switch button. If the button is not pressed then the LEDs will remain ON and when you hit the button , the LEDs will go OFF.
- Copy the below code and paste it into the Arduino software and compile.
int analogPin = A0;
int ledCount = 3;
int ledPins[] = {
2, 3, 4};
void setup() {
// loop over the pin array and set them all to output:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
}
}
void loop() {
// read the potentiometer:
int sensorReading = analogRead(analogPin);
// map the result to a range from 0 to the number of LEDs:
int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);
// loop over the LED array:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
// if the array element's index is less than ledLevel,
// turn the pin for this element on:
if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}
// turn off all pins higher than the ledLevel:
else {
digitalWrite(ledPins[thisLed], LOW);
}
}
}
- After compiling this code, get the hex file of code. The hex file and this simulation file is also given at the end of this post so you can download it from there.
- Now upload this hex file into this Arduino Lilypad and hit the RUN button
Note:
- If everything's goes fine then as youhit the run button, the LEDs will get ON as shown in the below figure:
- Now, when you press the button, these LEDs will go OFF as shown in the below figure:
- That's all, you have successfully implemented the Arduino Lilypad simulation in Proteus. :)
- In order to download this simulation and the hex file, click on the below buttons.
Download Proteus Simulation