Hello readers, we hope you all are doing great. Welcome to the 4th lecture of Section 5(ESP32 Sensor) in the ESP32 Programming Series. So far, we have discussed the ESP32 built-in sensors in this section. Today, we are going to interface an external embedded sensor(i.e. PIR Sensor) with the ESP32 Microcontroller board. At the start, we will discuss the basics of a PIR Sensor(HC-SR501) i.e. its pinout and working. After that, we will design a simple project to detect the motion with a PIR sensor and ESP32. Finally, we will display the motion detection results on the ESP32 WebServer.
We will use ESP32 interrupts to detect the motion. Interrupts are used when a microcontroller needs to continuously monitor an event while executing other tasks at the same time. We have already posted a tutorial on ESP32 Interrupts, which includes both software and hardware interrupts. In this tutorial, we are implementing the hardware interrupt(Hardware interrupts are the external interrupts that are caused by an external event). In our project, the hardware interrupt will be generated by the PIR sensor.
PIR motion sensor is mostly used in home automation & security projects, used to enable the system to respond automatically over human presence. Appliances connected to ESP32 will respond automatically(as per the instructions provided) whenever an interrupt is triggered by the PIR motion sensor. Let's first have a look at the working of PIR Sensor:
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | ESP32 | Amazon | Buy Now | |
In today's project, we will use the HC-SR501 PIR Sensor to detect the motion. PIR stands for Passive Infrared sensors. It uses a pair of pyroelectric sensors to detect heat energy in the surrounding environment. Both the sensors sit beside each other, and when a motion is detected or the signal differential between the two sensors changes the PIR motion sensor will return a LOW result (logic zero volts). It means that you must wait for the pin to go low in the code. When the pin goes low, the desired function can be called.
PIR Sensor has two variable resistors on its back side, used to adjust the Sensitivity and Detection Range, explained below:
Thermal sensing applications, such as security and motion detection, make use of PIR sensors. They're frequently used in security alarms, motion detection alarms, and automatic lighting applications.
Now let's interface the PIR Sensor with ESP32:
As I mentioned earlier, in today's project, we will design a motion detection project with ESP32 and PIR Sensor. In the first example, we will turn "ON" the LED on motion detection, while in the second project, we will display the results in the ESP32 WebServer.
Here's the list of the components for today's project:
Here's the circuit diagram for motion detection with ESP32 and PIR Sensor:
Now let's design the programming code for motion detection:
We are using Arduino IDE to compile and upload code into the ESP32 module. You need to first Install ESP32 in Arduino IDE to get started. Here's the code for motion detection:
//----Set GPIOs for LED and PIR Motion Sensor
const int led = 23;
const int PIRSensor = 4;
// -----Timer: Auxiliary variables
#define timeSeconds 10
unsigned long now = millis();
unsigned long lastTrigger = 0;
boolean startTimer = false;
//---Checks if motion was detected, sets LED HIGH and starts a timer
void IRAM_ATTR detectsMovement()
{
Serial.println( " MOTION DETECTED " );
Serial.println("Turning ON the LED");
digitalWrite(led, HIGH);
startTimer = true;
lastTrigger = millis();
}
void setup()
{
Serial.begin( 115200 ); // Serial port for debugging purposes
pinMode( PIRSensor, INPUT_PULLUP ); // PIR Motion Sensor mode INPUT_PULLUP
pinMode( led, OUTPUT );
digitalWrite( led, LOW );
attachInterrupt( digitalPinToInterrupt( PIRSensor ), detectsMovement, FALLING ); // Set PIRSensor pin as interrupt, assign interrupt function and set RISING mode
}
void loop()
{
now = millis();
if( startTimer && (now - lastTrigger > ( timeSeconds*500)))
{
Serial.println(" Turning OFF the LED " );
digitalWrite( led, LOW );
startTimer = false;
}
}
//----Set GPIOs for LED and PIR Motion Sensor
const int led = 23;
const int PIRSensor = 4;//-----Timer: Auxiliary variables
#define timeSeconds 10
unsigned long now = millis();
unsigned long lastTrigger = 0;
boolean startTimer = false;//---Checks if motion was detected, sets LED HIGH and starts a timer
void IRAM_ATTR detectsMovement()
{
Serial.println( " MOTION DETECTED " );
Serial.println("Turning ON the LED");
digitalWrite(led, HIGH);
startTimer = true;
lastTrigger = millis();
}void setup()
{
Serial.begin( 115200 ); // Serial port for debugging purposes
pinMode( PIRSensor, INPUT_PULLUP ); // PIR Motion Sensor mode INPUT_PULLUP
pinMode( led, OUTPUT );
digitalWrite( led, LOW );
attachInterrupt( digitalPinToInterrupt( PIRSensor ), detectsMovement, FALLING ); // Set PIRSensor pin as interrupt, assign interrupt function and set RISING mode
}We have activated the interrupt in the Setup Function, so when the PIR Sensor detects the motion, it will automatically execute the interrupt function, which will turn the LED ON and start the timer.
void loop()
{
now = millis();
if( startTimer && (now - lastTrigger > ( timeSeconds*500)))
{
Serial.println(" Turning OFF the LED " );
digitalWrite( led, LOW );
startTimer = false;
}
}This concludes the tutorial. I hope you find this tutorial helpful. Thanks for reading. See you soon with a new tutorial on ESP32. Take care !!!
Hello Geeks, I hope you all are doing great and enjoying your festive seasons. This time, we have come up with a new project which will make your festival a bit brighter so here comes a Christmas tree.
It is said that Christmas is the center of all the celebrations. Did you guys know the scientist who discovered the light bulb, Thomas Edison and his friends were the first to put up the light bulbs on the Christmas tree, and here we are going to keep that tradition forward? Well, it’s time to gear up for the next season of Christmas being tech-savvy. Hence we have decided to brighten up a Christmas tree with the usage of Arduino Uno and LEDs in real life.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | LEDs | Amazon | Buy Now | |
| 2 | Arduino Uno | Amazon | Buy Now | |
To make our festival a little safer, we will first make our Christmas tree in the simulation and for that, we will use the Proteus simulation software. Making it in the simulation will give us a good understanding of how it is going to work, and how we are about to design the Christmas tree such as the placements of lights and lighting patterns.
Proteus is a simulation tool for electronic projects. In this software, we can make approximately every type of electronic circuit and run the working simulation. It will show the real-time working simulation of the circuit and errors as well if any occurs.
It has a large database of mostly all types of electronic components but still, for some, we have to install libraries. In this project, we are using Arduino UNO and it is not pre-installed so we have to download it first.
Following components will be required to design our Christmas Tree
Mostly it has not been damaged yet.
Now let's start with the circuit diagram of our project. The first step would be to import all the components to the workspace of Proteus software.
We will be using one Arduino UNO for controlling the LEDs and six different colors of LEDs. Here we will make 6 rows and 6 columns of LEDs for our Christmas tree, so we will be using 6 Aqua color LEDs, 6 Green color LEDs, 6 Orange color LEDs, 6 White color LEDs, and 6 Yellow color LEDs.
After the connection of the circuit, let's start to code our Christmas tree:
? We have declared all the row and column pins in the output modes.
After completing the development side of the Christmas tree, it is time to test it.
Here is the working demo of our Christmas Tree
I hope we have covered all the points related to this project and you have enjoyed reading it. We can use this with the real component and decorate the Christmas tree or we can use some cardboard and insert the LEDs on them in the same way.
If you have any doubts regarding the project. And we will be glad to read about how you made your Christmas tree using this project and if you try any interesting new patterns with it, please let us know in the comment section.
Merry Christmas.
Servo Motors are among the most important actuators in robotics, with applications ranging from RC planes to automated door locks.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | ESP32 | Amazon | Buy Now | |
There are several specific types of electric motor applications in which the motor must rotate only at a specific angle. For such applications, we need a special type of motor with such a special arrangement that causes the motor to rotate at a specific angle for a given electric signal (input). The servo motor comes into effect for this purpose.
A servo motor is a linear or rotary actuator that enables accurate control of linear or angular position, acceleration, and velocity. It is made up of a motor and a sensor for position feedback. It also necessitates a fairly sophisticated controller, which is frequently a dedicated module designed specifically for use with servo motors.
The primary reason to use a servo motor is that it offers angular precision, which means that it will only rotate as far as we want it to before stopping and waiting for the next signal to take action. The servo motor, unlike a standard electric motor, begins to turn as soon as we apply input power to it and continues to rotate until we turn off the power. We cannot restrict the rotational progress of an electric motor, but we can control its speed and turn it on and off. Small servo motors are included in numerous beginner Arduino launcher kits since they are simple to use in small electronic projects and applications.
When compared to an Arduino, interfacing a servo motor to the ESP32 is extremely difficult because it does not support analogWrite(). However, it employs a variety of frequencies and timers, allowing all digital pins to be used as PWM pins and to send signals much faster than any Arduino.
Servo motor consists of three wires;
A servo motor is controlled by sending a PWM or pulse width modulated signal. A servo motor can only turn for a total of 180-degree movement (90 degrees in either direction).
The PWM signal sent to the motor specifies the position of the shaft, and the rotor will turn to the desired position depending on the duration of the pulse sent through the control wire.
We are using Arduino IDE to compile and upload code into the ESP32 module. To know more about Arduino IDE and how to use it, follow our previous tutorial i.e., on the ESP32 programming series.
https://github.com/RoboticsBrno/ServoESP32
#include <Servo.h>
static const int servoPin = 4;
Servo servo1;
void setup()
{
Serial.begin( 115200 );
servo1.attach( servoPin);
}
void loop() {
for(int posDegrees = 0;
posDegrees <= 180;
posDegrees++)
{
servo1.write( posDegrees );
Serial.println( posDegrees );
delay( 20);
}
for(int posDegrees = 180;
posDegrees >= 0;
posDegrees--)
{
servo1.write( posDegrees);
Serial.println( posDegrees);
delay(20);
}
}
Fig.
Fig. Serial monitor output
Fig. ESP32 and servo motor
Let’s create a web server to control the position of the servo motor. We will create a web page containing a slider to control the angle/position of the servo motor’s shaft.
We have also created a tutorial on creating a simple web server with ESP32.
#include <WiFi.h>
#include <Servo.h>
Servo servo1; // create servo object to control a servo
// twelve servo objects can be created on most boards
// GPIO the servo is attached to
static const int servoPin = 13;
// Replace with your network credentials
const char* ssid = "SSID";
const char* password = "PASSWORD";
// Set web server port number to 80
WiFiServer server(80);
// Variable to store the HTTP request
String header;
String valueString = String(5);
int angle_x = 0;
int angle_y = 0;
// Current time
unsigned long currentTime = millis();
// Previous time
unsigned long previousTime = 0;
// Define timeout time in milliseconds (example: 2000ms = 2s)
const long timeoutTime = 2000;
void setup() {
Serial.begin(115200);
servo1.attach(servoPin); // attaches the servo on the servoPin to the servo object
// Connect to Wi-Fi network with SSID and password
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
// Print local IP address and start web server
Serial.println("");
Serial.println("WiFi connected.");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
server.begin();
}
void loop(){
WiFiClient client = server.available(); // Listen for incoming clients
if (client) { // If a new client connects,
currentTime = millis();
previousTime = currentTime;
Serial.println("New Client."); // print a message out in the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected() && currentTime - previousTime <= timeoutTime) { // loop while the client's connected
currentTime = millis();
if (client.available()) { // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
header += c;
if (c == '\n') { // if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what's coming, then a blank line:
client.println("HTTP/1.1 200 OK");
client.println("Content-type:text/html");
client.println("Connection: close");
client.println();
// Display the HTML web page
client.println("<!DOCTYPE html><html>");
client.println("<head><meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">");
client.println("<link rel=\"icon\" href=\"data:,\">");
// CSS to style the slider
// Feel free to change the background-color and font-size attributes to fit your preferences
client.println("<style>body { text-align: justify; font-family: \"Trebuchet MS\", Arial; margin-left:auto; margin-right:auto;}");
client.println(".slider { width: 600px; }</style>");
client.println("<script src=\"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js\"></script>");
// Styling Web Page
client.println("</head><body><h1>Control Servo via ESP32</h1>");
client.println("<p>Angle: <span id=\"servoPos\"></span></p>");
client.println("<input type=\"range\" min=\"0\" max=\"180\" class=\"slider\" id=\"servoSlider\" onchange=\"servo(this.value)\" value=\""+valueString+"\"/>");
client.println("<script>var slider = document.getElementById(\"servoSlider\");");
client.println("var servoP = document.getElementById(\"servoPos\"); servoP.innerHTML = slider.value;");
client.println("slider.oninput = function() { slider.value = this.value; servoP.innerHTML = this.value; }");
client.println("$.ajaxSetup({timeout:2000}); function servo(pos) { ");
client.println("$.get(\"/?value=\" + pos + \"&\"); {Connection: close};}</script>");
client.println("</body></html>");
//GET /?value=180& HTTP/1.1
if(header.indexOf("GET /?value=")>=0) {
angle_x = header.indexOf('=');
angle_y = header.indexOf('&');
valueString = header.substring(angle_x+1, angle_y);
//Rotate the servo
servo1.write(valueString.toInt());
Serial.println(valueString);
}
// The HTTP response ends with another blank line
client.println();
// Break out of the while loop
break;
} else { // if you got a newline, then clear currentLine
currentLine = "";
}
} else if ( c != '\r' ) { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// Clear the header variable
header = "";
// Close the connection
client.stop();
Serial.println("Client disconnected.");
Serial.println(" ");
}
}
Fig.
Fig.
Fig.
Fig.
Fig
Fig.
Fig.
Fig.
Fig. Close the connection
Fig. Serial Monitor
Fig. Web Page
This concludes the tutorial. I hope you found this of some help and also to see you soon with a new tutorial on ESP32.
Rather than investing in new electronic equipment, we will use an Arduino board and some basic components to measure the capacitance. To make this project, we should have some working knowledge about the capacitor. Here, we will not discuss the in-depth working of capacitors, but we will talk briefly so that it would be easy to understand the working principle of our project.
The capacitor is an electronic component that basically stores the energy when applied to an electric field. It has two parallel terminals connected by two parallel conducting plates separated by a dielectric material. Dielectric materials are electrical insulators(resist to pass the current) that can be polarised by applying an electric field. When we connect a battery with the capacitor then due to potential difference, the electric field is created between two oppositely charged plates of the capacitor and this way the capacitor stores the energy.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | Capacitor | Amazon | Buy Now | |
| 2 | Resistor | Amazon | Buy Now | |
| 3 | LCD 16x2 | Amazon | Buy Now | |
| 4 | Arduino Uno | Amazon | Buy Now | |
To make this project, we will need some software to install. As we will make our project in the simulation, so for that we will install Proteus simulation software and for coding, we will use the Arduino IDE.
A brief about Proteus, it is a tool used for simulation and design of electronic circuits. Here we can design different types of electronic circuits and run the simulation. Although Proteus has a very big database for electronic components, still we need to install some libraries which we will use in this project.
You can download this whole project for example Proteus Simulation and Arduino Code, by tapping the below button:
Capacitance Measurement using ArduinoIn this project, we will use the following components-
Now let's talk about the working of this project. The capacitance of any capacitor is the amount of charge that is stored in that capacitor and its unit is Faraday (F). To measure the capacitance, we will use some basic properties of the capacitor.
So when we connect a power supply with a resistor across the terminals of a capacitor, it will take a certain amount of time to fully charge. And when we connect any discharging resistor as a load across it, then it will take a certain amount of time to fully discharge. And this charging and discharging time will be proportional to the capacitance of the capacitor and the charging resistor in the RC circuit.
We will use the time constant formula for the calculation of capacitance. The time constant of any capacitor is known as the time taken by the capacitor to charge 63 percent of applied voltage or the time taken by the capacitor to discharge to 33 percent of stored voltage.
Here,
T (Tau) = Time constant(Seconds)
R = Resistance (Ohms)
C= Capacitance (Farads)
Using the above principle, we will charge the capacitor using a resistor to reach the charge of the capacitor to 63 percent of applied voltage and we will measure the time taken by the capacitor to reach that point. As we know the resistor’s value and time constant, using these two, we can calculate the capacitance:
Note-Whenever uploading the code on the Arduino UNO, disconnect any wire which is connected to Rx(D0) and Tx(D1) pins, otherwise, it will give an error while uploading the code.
Now, we have a list of all the required components. Let's start connecting them.
While working on the real components, make sure you have connected the backlight of the LCD module and set the contrast properly otherwise nothing will be visible on the LCD module.
I hope we have covered all the points related to this project such as circuit diagrams, codes, and working simulation. And I think this will be a very useful project for your daily tinker life. Please let us know if you face any difficulties while making this project in the comment section below.
We will be happy to hear if you will make this project used in your projects.
Thanks for reading this article. All the best and see you in the next project.
We are familiar with multiple features of the ESP32 module. Like Wi-Fi capabilities, classic Bluetooth, Bluetooth low energy (BLE), inbuilt sensors etc.
Hello readers, I hope you all are doing great. We have already mentioned in our previous tutorials that, ESP32 is also featured with a Dual-Core Processor. Which provides better performance and efficiency.
In this tutorial, we will learn how to use ESP32’s dual cores. ESP32 has two (32-bit each) Tensilica Xtensa LX6 microprocessors namely, core0 and core1 which makes it a powerful dual-core microcontroller and hence stands apart from its predecessors.
When we compile and upload a code using Arduino IDE, we do not have to worry about which core executes the code. It just runs.
Fig. 1 ESP32 dual-core processor
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | ESP32 | Amazon | Buy Now | |
A FreeRTOS (real-time operating system) firmware is already available in the ESP32 module. FreeRTOS is helpful in improving the system performance and managing the resources of the module. FreeRTOS allows users to handle several tasks like measuring sensor readings, making a network request, controlling motor speed etc. all of them run simultaneously and independently.
FreeRTOS offers multiple APIs for different applications. Those APIs can be used to create tasks and make them run on different cores. You need to create tasks to assign a particular part of code to a specific core. You can also prioritize that on which core the code will run. Priority value starts with level_0.
Whenever we run a code on Arduino IDE, it runs on core_1 by default.
There is a function you can use to check on which core the code is running on.
xPortGetCoreID()
Run the following code in Arduino IDE:
void setup(){
Serial.begin(115200);
Serial.print( " setup() is running on: Core_" );
Serial.println( xPortGetCoreID() );
delay(1000);
}
void loop()
{
Serial.print( " loop() is running on: Core_" );
Serial.println( xPortGetCoreID() );
delay(1000);
}
Fig. 2 Serial Monitor
From the results on the serial monitor, you can see that both setup() function and loop() function are running on core_1.
Fig. 3
This function takes seven arguments:
Fig. 4
For example, we have created a function named task_code(). Inside the task_code() function a for(;;) loop is used which will create an infinite loop. All the instructions to be given for a particular core to perform a particular task like led blinking, sensor readings etc. will be written inside this for(;;) loop.
Fig. 5
You can use the function vTaskDelete() during the code execution to delete a task. This function takes the task handle (task) as an argument.
In this code we will use two LEDs to be processed by different core.
TaskHandle_t task1;
TaskHandle_t task2;
// Assign GPIOs pins to LEDs
const int led1 = LED_BUILTIN;
const int led2 = 25;
void setup() {
Serial.begin(115200 );
pinMode( led1, OUTPUT );
pinMode( led2, OUTPUT );
//create a task that will be executed in the Task1code() function, with priority 1 and executed on core 0
xTaskCreatePinnedToCore(task_1code, // Task function.
"Task1", // name of task.
10000, // Stack size of task
NULL, // parameter of the task
1, // priority of the task
&task1, // Task handle to keep track of created task
1); // pin task to core 1
delay(1000);
//create a task that will be executed in the Task2code() function, with priority 1 and executed on core 1
xTaskCreatePinnedToCore(task_2code, //Task function.
"task2", //name of task.
10000, //Stack size of task
NULL, //parameter of the task
1, //priority of the task
&task2, //Task handle to keep track of created task
0); //pin task to core 0
delay(1000);
}
//task_1code: blinks an LED every 1000 ms
void task_1code( void * pvParameters ){
Serial.print( "task1 running on: core " );
Serial.println( xPortGetCoreID() );
for(;;)
{
digitalWrite( led1, HIGH);
delay(1000);
digitalWrite(led1, LOW);
delay(1000);
}
}
//task_2code: blinks an LED every 500 ms
void task_2code( void * pvParameters )
{
Serial.print( "task2 running on: core " );
Serial.println(xPortGetCoreID() );
for(;;){
digitalWrite(led2, HIGH );
delay(500);
digitalWrite(led2, LOW );
delay(500);
}
}
void loop(){
Serial.print( " loop() is running on: Core " );
Serial.println( xPortGetCoreID() );
delay(1000);
}
Fig. 6
Fig. 7
Fig. 8 setup() function
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13 loop function
Components required:
Fig. 14 connecting LED with ESP32
Fig. 15 Results on the serial monitor
This concludes the tutorial. We hope you found this helpful and also hope to see you soon with a new tutorial on ESP32.
Hello readers, I hope you all are doing great. In our previous tutorial, we learnt how to make HTTP POST from ESP32 to the IFTTT server.
In this tutorial, we will learn about another application of the ESP32 module in the field of IoT (Internet of Things). We can publish multiple sensor readings from ESP32 to Google sheets via the IFTTT web service.
IFTTT is used as a third-party web service to integrate Google sheets with ESP32.
Fig. 1
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | ESP32 | Amazon | Buy Now | |
We are going to create an applet (on the IFTTT server) that is responsible to integrate the Webhooks and Google Sheets services.
While operating with the IFTTT server there are some services/utilities that we are going to deal with like Applets and Webhooks. Before getting started with the project, let’s first introduce you to those terms:
An Applet is a small application or a utility program, which is used for one or a few simple functions. It connects two or more devices or apps together. An applet provides integration between two devices or services to enable some functionality that those devices or services cannot do alone or on their own. An applet consists of actions and triggers.
Fig. 2
Fig. 3: Creating an Applet
Fig. 4: “If This”
Fig. 5: Search and Select Webhooks
Fig. 6: Receive a Web Request
Fig. 7: Create Trigger
Fig. 8: Then That
Fig. 9: Google Sheets
Fig. 10: Select an Action
Fig. 11: Connect to Google Sheets Service
Fig. 12: Allow IFTTT Service to Access Files of your Google Drive
Fig. 13: Complete Action Fields
Fig. 14: Applet Successfully Created
Before interfacing the IFTTT service (applet) with ESP32, let us test the applet whether it is created successfully or not.
Fig. 15
Fig. 16: Test your Applet
Fig. 17: IFTTT Folder in Google Drive
No external components are required as we are using the ESP32’s inbuilt sensors to take the readings.
Let’s have an overview of the project before writing the Arduino code:
#include <WiFi.h>
// Replace with your SSID and Password
const char* ssid = "SSID";
const char* password = "Password";
// Replace with your unique IFTTT URL resource
const char* serverName = "https://maker.ifttt.com/trigger/replace_this_with_eventName/with/key/replace_this_with_your_unique_key ";
// Maker Webhooks IFTTT
const char* server="maker.ifttt.com";
//----Timer for sleep
uint64_t uS_TO_S_FACTOR = 1000000; // Conversion factor for micro seconds to seconds
uint64_t TIME_TO_SLEEP = 900; //sleep for 15 minutes
void setup()
{
Serial.begin(115200);
delay(100);
Serial.print("Connecting to: ");
Serial.print(ssid);
WiFi.begin(ssid, password);
int timeout = 10 * 4; // 10 seconds
while( WiFi.status() != WL_CONNECTED && ( timeout-- > 0) )
{
delay(200);
Serial.print(".");
}
Serial.println(" ");
if(WiFi.status() != WL_CONNECTED )
{
Serial.println(" Failed to connect, going back to sleep ");
}
Serial.print("WiFi connected in: ");
Serial.print(millis());
Serial.print(", IP address: ");
Serial.println(WiFi.localIP());
makeIFTTTRequest();
// enable timer deep sleep
esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);
Serial.println("Going to sleep now");
esp_deep_sleep_start(); // start deep sleep for 900 seconds (15 minutes)
}
void loop()
{
// sleeping so wont get here
}
void makeIFTTTRequest()
{
Serial.print("Connecting to ");
Serial.print(server);
WiFiClient client;
int retries = 5;
while(!!!client.connect(server, 80) && (retries-- > 0))
{
Serial.print(".");
}
Serial.println();
if(!!!client.connected())
{
Serial.println(" Failed to connect... ");
}
Serial.print(" Request server: ");
Serial.println( serverName );
// Hall sensor values
String jsonObject = String("{\"value1\":\"") +
hallRead() +
"\",\"value2\":\"" + hallRead()
+ "\",\"value3\":\"" +
hallRead() + "\"}";
client.println(String("POST ") + serverName + " HTTP/1.1");
client.println(String("Host: ") + server);
client.println("Connection: close\r\nContent-Type: application/json");
client.print("Content-Length: ");
client.println(jsonObject.length());
client.println();
client.println(jsonObject);
int timeout = 5 * 10; // 5 seconds
while(!!!client.available() && (timeout-- > 0)){
delay(100);
}
if(!!!client.available()) {
Serial.println("No response...");
}
while(client.available()){
Serial.write(client.read());
}
Serial.println("\nclosing connection");
client.stop();
}
Fig. 18: Library Files
Fig. 19: Network Credentials
Fig. 20
Fig. 21
Note: The ESP32 sleep time should not be very short. A very short sleep time can result in the exceeded limit of requests imposed by the IFTTT service.
Fig. 22: Timer
Fig. 23: Serial Monitor
Fig. 24: Wi-Fi
Fig. 25
Fig. 26
Fig. 27
Fig. 28
Fig. 29
Fig. 30
Fig. 31: Hall Sensor Readings on Google Sheets
Fig. 32: Serial Monitor
This concludes the tutorial. I hope you found this of some help and also to see you soon with the new tutorial on ESP32.
New workers are three times more likely to sustain an injury in their first month than workers with a year's experience on the job. By improving employee training and tailoring programs to the demands of each individual role, you can better minimize the risk of accident and injury (a lab employee, for instance, requires vastly different training to an industrial line worker). In fact, OSHA advises implementing different plans for five key areas in order to form a comprehensive health and safety approach: hazard assessment; hazard mitigation; hazard prevention; electrical safety; and safety training. Additionally, it’s important to provide refresher training sessions on a regular basis. Never make health and safety training a one-time occurrence. By reiterating health and safety information and advice throughout the year, you can ensure workers maintain awareness of best practices.
A health and safety management system is essential for identifying and resolving workplace hazards and protecting workers, as well as improving overall operational performance. In fact, it can reduce total costs arising from occupational injuries by at least 20-40%. To devise your system, OSHA recommends first identifying any health and safety issues, including, risks and hazards, management system deficiencies, and opportunities for improvement, and then prioritizing those issues. You can then determine the goals of your health and safety management system in order to maximize workplace safety and minimize risks. If an employee does sustain an injury while on the job, it’s important they inform themselves of their legal rights. Filing a lawsuit for personal injury damages can help injured employees secure financial compensation to cover the cost of medical bills and lose income, Aaron Allison Law explains.
By incentivizing compliance, you have a better chance of ensuring your employees adhere to health and safety standards. Industrial workplaces often involve high-risk activities dealing with heavy machinery, electrical tools, and toxic chemicals on a daily basis. As such, employees can easily become too comfortable and lax, which results in potential injury or death. Incentivizing compliance could, for example, involve rewarding employees or managers when they achieve pre-set health and safety goals. Similarly, examples of non-compliance with rules and guidelines should also be corrected.
Health and safety should be a priority in all industrial workplaces. By improving employee training, implementing a health and safety management system, and incentivizing compliance, you can keep your workplace as safe as possible for employees.
ESP32 is a powerful chip for Internet of Things applications. This tutorial is also based on another ESP32 application in the field of IoT.
Hello readers, I hope you all are doing great. In the previous tutorial, we learned how to send sensor readings from ESP32 to the cloud (ThingSpeak webserver).
In this tutorial, we will learn to send HTTP POST requests from the ESP32 board to ThingSpeak and IFTTT APIs.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | ESP32 | Amazon | Buy Now | |
Fig. 1 Hypertext Transfer Protocol
HTTP stands for hypertext transfer control and it is a protocol for transferring data between a web client and a web server. Hyper text transfer protocol was invented alongside HTML (Hypertext markup language) to create the first interactive, text-based web browser: the original www or World Wide Web.
Server and client communication process over HTTP:
Fig. 2 HTTP POST Request
Hypertext transfer protocol uses particular request methods to execute various tasks. Two mostly used HTTP request methods are: HTTP GET request and HTTP POST request.
HTTP GET request is generated to request data from a specific resource and the HTTP POST request method is used to send data from the client device to the server to create or update resources.
In this tutorial, we will demonstrate only the HTTP POST method with ThingSpeak and IFTTT web services.
Features of the HTTP POST request:
IFTT stands for If This Then That. It is a free web service for making different services like email, weather services, Twitter etc to connect.
IFTTT means if a service is triggered, other IFTTT services will take action.
Fig. 3 IFTTT
IFTTT acts as a bridge between ESP32 and other web services. Some of the tasks the ESP32 board can perform with the IFTTT API service are:
IFTTT comprises Applets and Applets further contains two IFTTT services namely trigger and action.
You can use the applets created by a company or can also create your own applet. To use the IFTTT applet with ESP32, we need to create an applet by ourselves. Such applet will contain Webhooks service to interact directly with ESP32 and other services that you want to use like email, Twitter service etc.
There are cases while using ESP32 with the IFTTT: either ESP32 will trigger the IFTTT to do some task or the IFTTT triggers ESP32 to do some task.
Steps to trigger IFTTT via ESP32
Enter the following link in the web browser: https://ifttt.com
Fig. 4 Creating an Applet
Fig. 5 ” If This”
Fig. 6 Search and Select Webhooks
Fig. 7 Receive a Web Request
Fig. 8 Create Trigger
Fig. 9 Then that
Fig. 10 Selecting a Service
Fig. 11
Fig. 12 To Trigger an Event
Fig. 13 Event Successfully Triggered
#include <WiFi.h>
#include <HTTPClient.h>
//---------Netwrok Credentials
const char* ssid = "SSID";
const char* password = "Password";
const char* serverName = "http://maker.ifttt.com/trigger/ESP32_test/with/key/Enter you API key";
unsigned long lastTime = 0;
unsigned long timerDelay = 15000;
void setup()
{
Serial.begin(115200);
WiFi.begin(ssid, password);
Serial.println("Connecting");
while(WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to WiFi network with IP Address: ");
Serial.println(WiFi.localIP());
// Random seed is a number used to initialize a pseudorandom number generator
randomSeed(hallRead());
}
Void Loop()
//Send an HTTP POST request after every 15 seconds
if ((millis() - lastTime) > timerDelay)
{
//Check WiFi connection status
if(WiFi.status()== WL_CONNECTED)
{
WiFiClient client;
HTTPClient http;
// Your Domain name with URL path or IP address with path
http.begin(client, serverName);
// Specify content-type header
http.addHeader("Content-Type", "application/x-www-form-urlencoded");
// Data to send with HTTP POST
String httpRequestData = "value1=" + String(random(25)) + "&value2=" + String(random(25))+ "&value3=" + String(random(25));
// Send HTTP POST request
int httpResponseCode = http.POST(httpRequestData);
/*
// If you need an HTTP request with a content type: application/json, use the following:
http.addHeader("Content-Type", "application/json");
// JSON data to send with HTTP POST
String httpRequestData = "{\"value1\":\"" + String(random(40)) + "\",\"value2\":\"" + String(random(40)) + "\",\"value3\":\"" + String(random(40)) + "\"}";
// Send HTTP POST request
int httpResponseCode = http.POST(httpRequestData);
*/
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
Serial.println("successfully conected to host");
// Free resources
http.end();
}
else
{
Serial.println("WiFi Disconnected");
}
lastTime = millis();
}
}
Fig. Libraries
Fig. Network Credentials
Fig.
Fig.
Fig.
Fig.
Fig
Fig.
Fig.
Fig.
Fig. 14 Serial Monitor
Fig. 15 View Activity
Fig. 16 Received data.
Fig. 17 Email Received from IFTTT Server
We have already posted an article on sending sensor readings from ESP32 to ThingSpeak. In this article, we will learn how to send HTTP POST requests from ESP32 to send JSON data to the ThigSpeak server.
ThingSpeak is a web service operated by MathWorks where we can send sensor readings/data to the cloud. We can also visualize and act on the data (calculate the data) posted by the devices to ThingSpeak. The data can be stored in either private or public channels.
Steps to be followed to access ThingSpeak API:
Fig. 18 Getting Started for Free
Fig. 19 Create New Account
Fig. 20 MathWorks Sign in
Fig. 21 New Channel
Fig. 22 Create a New Channel
//-----------Libraries
#include <WiFi.h>
#include <HTTPClient.h>
//-----------Network Credentials
const char* ssid = "replace with your network SSID";
const char* password = "replace with netwrok password";
// Domain Name with full URL Path for HTTP POST Request
const char* serverName = "http://api.thingspeak.com/update";
// Service API Key
String apiKey = "Write API Key";
unsigned long lastTime = 0;
unsigned long timerDelay = 5000; //to add delay of 5sec
void setup()
{
Serial.begin(115200);
WiFi.begin(ssid, password); //initialize ESP32 wifi module
Serial.println("Connecting");
while(WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("Connected to WiFi network with IP Address: ");
Serial.println(WiFi.localIP());
Serial.println("Timer set to 10 seconds (timerDelay variable), it will take 10 seconds before publishing the first reading.");
// Random seed is a number used to initialize a pseudorandom number generator
randomSeed(analogRead(25));
}
void loop()
{
//Send an HTTP POST request after every 5 seconds
if ((millis() - lastTime) > timerDelay)
{
//Check the WiFi connection status
if(WiFi.status()== WL_CONNECTED)
{
WiFiClient client;
HTTPClient http;
http.begin( client, serverName );
http.addHeader("Content-Type", "application/json");
String httpRequestData = "{\"api_key\":\"" + apiKey +
"\",\"field1\":\"" +
String(random(30)) + "\"}";
int httpResponseCode = http.POST(httpRequestData);
Serial.print("HTTP Response code: ");
Serial.println(httpResponseCode);
// Free resources
http.end();
}
else {
Serial.println("WiFi Disconnected");
}
lastTime = millis();
}
}
Fig.
Fig.
Fig.
Fig. : data (JSON) Chart on ThingSpeak
This concludes the tutorial. I hope you found this of some help and also to see you soon with the new tutorial on ESP32.
HCI is a great way to reduce operating costs and simplify IT by using a single virtual environment to combine, compute, storage and networking. This virtual-box solution is flexible and affordable enough, allowing even smaller companies and startups to purchase HCI architecture to connect and interact with their remote workers, branch offices, and IoT applications.
According to researchers, the global HCI market will continue to grow at a steady pace during the next five years. Increasing customer demand and rapid adoption of SaaS and other cloud-based solutions due to the changes in daily operations of most businesses caused by the Covid-19 pandemic has brought HCI into the spotlight. More and more vendors are offering hyperconverged solutions, both for cloud and on-premise infrastructures.
According to experts, the HCI market was valued at an impressive $7.34 billion in 2020. It's predicted to surpass the $10 billion mark by 2025. Backup and recovery solutions and performance-enhancing environments remain the main drivers of market growth. Other niches where HCI solutions are popular include VM farms, desktop virtualization software, and database management.
Server providers and other IT vendors are divided on the issue of HCI. While some of them seem to have exited the HCI market completely, others, including even a few hardware vendors, have doubled their efforts, focusing on selling software-only products.
Hyperconverged infrastructure fits seamlessly with Edge computing. Even smaller companies have to rely on Edge if they have branch offices or operate in remote locations. Industries like retail and banking use Edge as their default option. Since HCI removes the need for separate storage and networking devices, combining Edge with HCI creates natural synergy. Connecting thin clients and VDI workstations to the company's data center running on HCI improves the systems' reliability and makes it harder to breach from the outside. From the business point of view, partnering with a single HCI vendor instead of several hardware providers leads to cost reduction and better control and maintenance. HCI solutions consume less power and take up less space than their standard hardware counterparts.
Adoption of high-speed mobile networks like 5G will lead to further growth of Edge data centers using HCI. Enterprise data centers will either switch to this new business model or will provide HCI solutions alongside their traditional IT silos. In short, the HCI will continue to co-evolve alongside Edge, expanding from the niche of serving remote office environments to other businesses that look to cut costs, reduce storage capacity and benefit from centralized management of resources that HCI offers.
When it comes to IT infrastructure, the hybrid cloud has become the default option for most companies. Hyperconverged infrastructure can serve as the backbone of the hybrid- and multi-cloud platforms. Since HCI runs on widely-used x86 infrastructure and doesn't require tweaking and overhauling, cloud service providers switch from traditional storage/compute/network silos to hyperconverged alternatives.
Major players like Dell and Amazon are rapidly moving into the HCI niche. The new Dell Technologies Cloud runs on the VxRail platform, which is one of the HCI market leaders. AWS now offers Nutanix's hyperconverged infrastructure available as a service. Microsoft has come up with Azure Stack HCI, a powerful solution for hybrid clouds.
Hyperconverged infrastructure can become a promising alternative to popular public clouds like AWS or Microsoft Azure. The biggest selling points of HCI are its ability to scale, reduced costs, better performance, and control.
As mentioned previously, backup and data recovery remain the main market driver for HCI adoption. Due to the increasing number of cyberattacks, infrastructure security becomes one of the primary concerns for most companies. HCI allows to backup data on the fly, creating healthy redundancy. It's a cheaper solution since it doesn't require third-party solutions for data backup and disaster recovery. It also brings down costs associated with storage requirements, making hyperconverged infrastructure the most affordable and attractive option for backup and disaster recovery on the market right now.
Hyperconverged infrastructure will see increased adoption both by enterprise-level companies and data centers. It has found its natural synergy with Edge computing. The need for increased security will accelerate HCI adoption in the niche of backup and disaster recovery. The popularity of hybrid cloud solutions will also increase the number of companies using HCI for their IT needs.
Hello friends! I hope you all had a great start to the new year.
In our first lecture, we had looked at the MATLAB prompt and also learned how to enter a few basic commands that use math operations. This also allowed us to use the MATLAB prompt as an advanced calculator. Today we will look at the various MATLAB keywords, and a few more basic commands and MATLAB functions, that will help us keep the prompt window organized and help in mathematical calculations. We are also going to get familiar with MATLAB’s interface and the various windows. We will also write our first user-defined MATLAB functions.
Like any programming language, MATLAB has its own set of keywords that are the basic building blocks of MATLAB. These 20 building blocks can be called by simply typing ‘iskeyword’ in the MATLAB prompt.
The list of 21 MATLAB keywords obtained as a result of running this command is as follows:
To test if the word while is a MATLAB keyword, we run the command
iskeyword(‘while’)
The output ‘1’ is saying that the result is ‘True’, and therefore, ‘while’ is indeed a keyword.
‘logical’ in the output refers to the fact that this output is a datatype of the type ‘logical’. Other data types include ‘uint8’, ‘char’ and so on and we will study these in more detail in the next lecture.
Apart from the basic arithmetic functions, MATLAB also supports relational operators, represented by symbols and the corresponding functions which look as follows:
Here, we create a variable ‘a’ which stores the value 1. The various comparison operators inside MATLAB used here, will give an output ‘1’ or ‘0’ which will mean ‘True’ or ‘False’ with respect to a particular statement.
Apart from these basic building blocks, MATLAB engineers have made available, a huge library of functions for various advanced purposes, that have been written using the basic MATLAB keywords only.
We had seen previously that the double arrowed (‘>>’) MATLAB prompt is always willing to accept command inputs from the user. Notice the ‘’ to the left of the MATLAB prompt, with a downward facing arrow. Clicking this downward facing arrow allows us to access the various in-built MATLAB functions including the functions from the various installed toolboxes. You can access the entire list of in-built MATLAB functions, including the trigonometric functions or the exponents, logarithms, etc.
Here are a few commands that we recommend you to try that make use of these functions:
A = [1,2,3,4];
B = sin(A);
X = 1:0.1:10;
Y = linspace(1,10,100);
clc
clear all
quit
Notice that while creating a matrix of numbers, we always use the square braces ‘[]’ as in the first line, whereas, the input to a function is always given with round brace ‘()’ as in the second line.
We can also create an ordered matrix of numbers separated by a fixed difference by using the syntax start:increment:end, as in the third command.
Alternatively, if we need to have exactly 100 equally separated numbers between a start and and end value, we can use the ‘linspace’ command.
Finally, whatever results have been output by the MATLAB response in the command window can be erased by using the ‘clc’ command which stands for ‘clear console’, and all the previously stored MATLAB variables can be erased with the ‘clear all’ command.
To exit MATLAB directly from the prompt, you can use the ‘quit’ command.
In the next section, let us get ourselves familiarized with the MATLAB environment.
A typical MATLAB work environment looks as follows. We will discuss the various windows in detail:
When you open MATLAB on your desktop, the following top menu is visible. Clicking on ‘new’ allows us to enter the editor window and write our own programs.
You can also run code section by section by using the ‘%%’ command. For beginners, I’d say that this feature is really really useful when you’re trying to optimize parameters.
On the top, we have the menu bar and the toolbar. This is followed by the address of the current directory that the user is working in.
By clicking on ‘New’ option, the user can choose to generate a new script, or a new live script, details of which we will see in the next section.
Under the Current Folder window, you will see all the files that exist in your current directory. If you select any particular file, you can also see it details in the bottom panel as shown below.
The Editor Window will appear when you open a MATLAB file with the extension ‘.m’ from the current folder by double clicking it, or when you select the ‘New Script’ option from the toolbar. You can even define variables like you do in your linear algebra class.
The code in the editor can also be split into various sections using the ‘%%’ command. Remember that a single ‘%’ symbol is used to create a comment in the Editor Window.
Remember that the semicolon ‘;’ serves to suppress the output. Whenever you create new variables, the workspace will start showing all these variables. As we can see, the variables named ‘a’, ‘b’, ‘c’, and ‘x’, ‘y’, ‘z’. For each variable, we have a particular size, and a type of variable, which is represented by the ‘Class’. Here, the ‘Class’ is double for simple numbers.
You can directly right click and save any variable, directly from this workspace, and it will be saved in the ‘.mat’ format in the current folder.
If however, you open a ‘.mlx’ file from the current folder, or select the option to create a ‘New Live Script’ from the toolbar, the Live Editor window wil open instead.
With the Live Script, you can get started with the symbolic manipulation, or write text into the MATLAB file as well. Live scripts can also do symbolic algebraic calculation in MATLAB.
For example, in the figure below, we define symbol x with the command
syms x
We click ‘Run’ from the toolbar to execute this file.
The Live Editor also allows us to toggle between the text and the code, right from the toolbar. After that, the various code sections can be run using the ‘Run’ option from the toolbar and the rendered output can be seen within the Live Editor.
Finally, there is the command history window, which will store all the previous commands that were entered on any previous date in your MATLAB environment.
Whenever you generate a plot, the figure window will appear which is an interactive window with it’s own toolbar, to interact with the plots.
We use the following commands to generate a plot, and you can try it too:
X = 1:0.1:2*pi;
Y = sin(X)
plot(X,Y)
The magnifier tools help us to zoom into and out of the plot while the ‘=’ tool helps us to find the x and y value of the plot at any particular point.
Also notice that now, the size of the ‘X’ and ‘Y’ variables is different, because we actually generated a matrix instead of assigning a single number to the variable.
By selecting New Function from the toolbar, you can also create a new user-defined function and save it as an m-file. The name of this m-file is supposed to be the same as the name of the function. The following template gets opened when you select the option to create a new user-defined function:
The syntax function is used to make MATLAB know that what we are writing is a function filee. Again notice that the inputs to the function, inputArg1 and inputArg2, are inside the round braces. The multiple outputs are surrounded by square braces because these can be a matrix. We will create a sample function SumAndDiff using this template, that will output the sum and difference of any two numbers. The function file SumAndDiff.m looks as follows:
Once this function is saved in the current folder, it can be recognized by a current MATLAB script or the MATLAB command window and used.
Exercises:
Run the following command in the MATLAB prompt:
I = imread(‘ngc6543a.jpg’);
This calls the image titled ‘ngc6543a.jpg’ which is stored inside MATLAB itself for example purposes. Notice the size of this image variable I in the workspace. You will interestingly find this to be a 3D matrix. Also note the class of this variable.
In the next tutorial, we will deep dive into the MATLAB data types, the format of printing these data types and write our first loops inside MATLAB.
