Class : 8 Duration : 3 Hours
- Discussion About Previous Class
- PWM, Servo Control Theory
- MQTT
- Making a Complete Project to Control 3 LED using Adafruit IoT
Basic of PWM :
https://www.arduino.cc/en/Tutorial/PWM
Servo Control :
Step 1:
Install Servo Library from Arduino IDE > Sketch > Included Library > ESP32 Servo
Step 2:
https://randomnerdtutorials.com/esp32-servo-motor-web-server-arduino-ide/
See Details Here : [http://mqtt.org/faq](http://mqtt.org/faq)
MQTT stands for MQ Telemetry Transport. It is a publish/subscribe, extremely simple and lightweight messaging protocol, designed for constrained devices and low-bandwidth, high-latency or unreliable networks. The design principles are to minimise network bandwidth and device resource requirements whilst also attempting to ensure reliability and some degree of assurance of delivery. These principles also turn out to make the protocol ideal of the emerging “machine-to-machine” (M2M) or “Internet of Things” world of connected devices, and for mobile applications where bandwidth and battery power are at a premium.
Some important topics must need to understand about MQTT is MQTT Broker, Publish, Subscribe. Teacher will explain about this topics briefly. Some Links :
https://www.youtube.com/watch?v=2aHV2Fn0I60
https://www.youtube.com/watch?v=iRUI3y3all4
Control 3 LED Using Smartphone App using Adafruit IoT Platform
Step 1: Install Adafruit_mqtt Library in Arduino
Step 2: Create a free account in io.adafruit.com
Step 3: Copy and Paste Code to Arduino IDE
/***************************************************
Adafruit MQTT Library ESP32 Example
Edited by Syed Razwanul Haque (Nabil)
CEO and Founder, www.cruxbd.com
www.youtube.com/Nabilphysics
This is a very basic code. I upload it just for an IDEA
Three or more LED can be controlled by this code using adafruit IoT
Works great with Adafruit's Huzzah ESP board & Feather
----> https://www.adafruit.com/product/2471
----> https://www.adafruit.com/products/2821
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
Written by Tony DiCola for Adafruit Industries.
MIT license, all text above must be included in any redistribution
****************************************************/
#include "WiFi.h"
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
// the on off button feed turns this LED on/off
#define LED1 1 //GPIO 1
#define LED2 2 //GPIO 2
#define LED3 3 //GPIO 3
/************************* WiFi Access Point *********************************/
#define WLAN_SSID "yourSSID"
#define WLAN_PASS "yourPassword"
/************************* Adafruit.io Setup *********************************/
#define AIO_SERVER "io.adafruit.com"
#define AIO_SERVERPORT 1883 // use 8883 for SSL
// You have to replace it with your own User name and AIO key
#define AIO_USERNAME "crux"
#define AIO_KEY "2dacfc5913343434b3ac09718cafe124"
/************ Global State (you don't need to change this!) ******************/
// Create an ESP8266 WiFiClient class to connect to the MQTT server.
WiFiClient client;
// or... use WiFiFlientSecure for SSL
//WiFiClientSecure client;
// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_USERNAME, AIO_KEY);
/****************************** Feeds ***************************************/
// Notice MQTT paths for AIO follow the form: <username>/feeds/<feedname>
Adafruit_MQTT_Subscribe onoffbutton1 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff1");
Adafruit_MQTT_Subscribe onoffbutton2 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff2");
Adafruit_MQTT_Subscribe onoffbutton3 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff3");
/*************************** Sketch Code ************************************/
void MQTT_connect();
void setup() {
pinMode(LED1, OUTPUT);
pinMode(LED2, OUTPUT);
pinMode(LED3, OUTPUT);
digitalWrite(LED1,LOW);
digitalWrite(LED2,LOW);
digitalWrite(LED3,LOW);
Serial.begin(115200);
Serial.println("\n Starting");
delay(10);
Serial.println(F("MQTT Switch demo"));
Serial.println(WiFi.SSID());
// Connect to WiFi access point.
Serial.println(); Serial.println();
Serial.print("Connecting to ");
Serial.println(WLAN_SSID);
WiFi.begin(WLAN_SSID, WLAN_PASS);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println();
Serial.println("WiFi connected");
Serial.println("IP address: "); Serial.println(WiFi.localIP());
// Setup MQTT subscription for onoff & slider feed.
mqtt.subscribe(&onoffbutton1);
mqtt.subscribe(&onoffbutton2);
mqtt.subscribe(&onoffbutton3);
}
uint32_t x=0;
void loop() {
// Ensure the connection to the MQTT server is alive (this will make the first
// connection and automatically reconnect when disconnected). See the MQTT_connect
// function definition further below.
MQTT_connect();
// this is our 'wait for incoming subscription packets' busy subloop
// try to spend your time here
Adafruit_MQTT_Subscribe *subscription;
while ((subscription = mqtt.readSubscription(10000))) {
// Check if its the onoff button feed
if (subscription == &onoffbutton1) {
Serial.print(F("On-Off button: "));
Serial.println((char *)onoffbutton1.lastread);
if (strcmp((char *)onoffbutton1.lastread, "ON") == 0) {
digitalWrite(LED1, HIGH);
}
if (strcmp((char *)onoffbutton1.lastread, "OFF") == 0) {
digitalWrite(LED1, LOW);
}
}
if (subscription == &onoffbutton2) {
Serial.print(F("On-Off button 2: "));
Serial.println((char *)onoffbutton2.lastread);
if (strcmp((char *)onoffbutton2.lastread, "ON") == 0) {
digitalWrite(LED2, HIGH);
}
if (strcmp((char *)onoffbutton2.lastread, "OFF") == 0) {
digitalWrite(LED2, LOW);
}
}
if (subscription == &onoffbutton3) {
Serial.print(F("On-Off button 3: "));
Serial.println((char *)onoffbutton3.lastread);
if (strcmp((char *)onoffbutton3.lastread, "ON") == 0) {
digitalWrite(LED3, HIGH);
}
if (strcmp((char *)onoffbutton3.lastread, "OFF") == 0) {
digitalWrite(LED3, LOW);
}
}
// // check if its the slider feed
// if (subscription == &slider) {
// Serial.print(F("Slider: "));
// Serial.println((char *)slider.lastread);
// uint16_t sliderval = atoi((char *)slider.lastread); // convert to a number
// analogWrite(PWMOUT, sliderval);
// }
}
// ping the server to keep the mqtt connection alive
if(! mqtt.ping()) {
mqtt.disconnect();
}
}
// Function to connect and reconnect as necessary to the MQTT server.
// Should be called in the loop function and it will take care if connecting.
void MQTT_connect() {
int8_t ret;
Serial.print("Connecting to MQTT... ");
uint8_t retries = 3;
while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected
Serial.println(mqtt.connectErrorString(ret));
Serial.println("Retrying MQTT connection in 5 seconds...");
mqtt.disconnect();
delay(5000); // wait 5 seconds
retries--;
if (retries == 0) {
// basically die and wait for WDT to reset me
while (1);
}
}
Serial.println("MQTT Connected!");
}
Step 4: From [Adafruit_MQTT_Subscribe onoffbutton1 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff1");](Adafruit_MQTT_Subscribe onoffbutton1 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff1");) copy AIO Key and paste in this code
Step 5: Click Dashboard > Actions > New Dashboard and give it a name(e.g. IoT_Switch)
Step 6: Click + button > Toggle Switch and than create three switch (onoff1, onoff2, onoff3 ) make sure this name matches your code. e.g.
Adafruit_MQTT_Subscribe onoffbutton1 = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/onoff1");
Step 7: Upload code to ESP32 and open Serial Monitor and check
Step 8: Attach 3 Resistor Series with 3 LED in GPIO Pin 1,2,3 and check its working when you changing Toggle Button in adafruit website.
Step 9: Download MQTT Dashboard app in your smartphone
Step 10: Give necessary info same as io.adafruit.com and check everything working properly.
