Ruchir Sharma
Published © GPL3+

Raspberry Pi Talking to ESP8266 Using MQTT

Control LED from both server and client side using MQTT.

IntermediateFull instructions provided2 hours43,336
Raspberry Pi Talking to ESP8266 Using MQTT

Things used in this project

Hardware components

Raspberry Pi 3 Model B
Raspberry Pi 3 Model B
×1
NodeMCU ESP8266 Breakout Board
NodeMCU ESP8266 Breakout Board
×1
LED (generic)
LED (generic)
×2
Pushbutton switch 12mm
SparkFun Pushbutton switch 12mm
×2
Resistor 10k ohm
Resistor 10k ohm
×1
Resistor 475 ohm
Resistor 475 ohm
×2

Story

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Schematics

RPi_led

NodeMCU_led

Code

NodeMCU_led

Arduino
#include <ESP8266WiFi.h> 
#include "Adafruit_MQTT.h" 
#include "Adafruit_MQTT_Client.h" 
/************************* WiFi Access Point *********************************/ 
#define WLAN_SSID       "Your SSID" 
#define WLAN_PASS       "PASSWORD" 

#define MQTT_SERVER      "192.168.1.68" // static ip address
#define MQTT_PORT         1883                    
#define MQTT_USERNAME    "" 
#define MQTT_PASSWORD         "" 

#define LED_PIN     5                // Pin connected to the LED. GPIO 2 (D4) 
#define BUTTON_PIN  4               // Pin connected to the button. GPIO 15 (D8) 

/************ Global State ******************/ 

// Create an ESP8266 WiFiClient class to connect to the MQTT server. 
WiFiClient client; 
// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details. 
Adafruit_MQTT_Client mqtt(&client, MQTT_SERVER, MQTT_PORT, MQTT_USERNAME, MQTT_PASSWORD); 
/****************************** Feeds ***************************************/ 
// Setup a feed called 'pi_led' for publishing. 

// Notice MQTT paths for AIO follow the form: <username>/feeds/<feedname> 
Adafruit_MQTT_Publish pi_led = Adafruit_MQTT_Publish(&mqtt, MQTT_USERNAME "/leds/pi"); 
// Setup a feed called 'esp8266_led' for subscribing to changes. 

Adafruit_MQTT_Subscribe esp8266_led = Adafruit_MQTT_Subscribe(&mqtt, MQTT_USERNAME "/leds/esp8266"); 
/*************************** Sketch Code ************************************/ 

void MQTT_connect(); 
void setup() { 
 Serial.begin(115200); 
 delay(10); 
 pinMode(LED_PIN, OUTPUT); 
 digitalWrite(LED_PIN, LOW); 
 // Setup button as an input with internal pull-up. 
pinMode(BUTTON_PIN, INPUT_PULLUP); 
 Serial.println(F("RPi-ESP-MQTT")); 
 // 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 esp8266_led feed. 
 mqtt.subscribe(&esp8266_led); 
} 
uint32_t x=0; 
void loop() { 
  // Check if the button has been pressed by looking for a change from high to 
 // low signal (with a small delay to debounce). 
 int button_first = digitalRead(BUTTON_PIN); 
 // Ensure the connection to the MQTT server is alive (this will make the first 
 // connection and automatically reconnect when disconnected).  See the MQTT_connect 
 MQTT_connect(); 
 // this is our 'wait for incoming subscription packets' busy subloop 
 // try to spend your time here 
 // Here its read the subscription 
 Adafruit_MQTT_Subscribe *subscription; 
 while ((subscription = mqtt.readSubscription())) { 
   if (subscription == &esp8266_led) { 
     char *message = (char *)esp8266_led.lastread; 
     Serial.print(F("Got: ")); 
     Serial.println(message); 
        // Check if the message was ON, OFF, or TOGGLE. 
     if (strncmp(message, "ON", 2) == 0) { 
       // Turn the LED on. 
       digitalWrite(LED_PIN, HIGH); 
     } 
     else if (strncmp(message, "OFF", 3) == 0) { 
       // Turn the LED off. 
       digitalWrite(LED_PIN, LOW); 
     } 
     else if (strncmp(message, "TOGGLE", 6) == 0) { 
       // Toggle the LED. 
       digitalWrite(LED_PIN, !digitalRead(LED_PIN)); 
} 
   } 
 } 
 delay(20); 
 int button_second = digitalRead(BUTTON_PIN); 
 if ((button_first == HIGH) && (button_second == LOW)) { 
   // Button was pressed! 
   Serial.println("Button pressed!"); 
   pi_led.publish("TOGGLE"); 
 } 
} 
// Function to connect and reconnect as necessary to the MQTT server. 

void MQTT_connect() { 
 int8_t ret; 
 // Stop if already connected. 
 if (mqtt.connected()) { 
   return; 
 } 
 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!"); 
}

NodeMCU_ledtest

Arduino
Simple program to check led and button with NodeMCU
int ledpin = 5;     // D1(GPIO 5)
int button = 4;     //D2(GPIO 4)
int buttonState=0;
void setup() {
 pinMode(ledpin, OUTPUT);
 pinMode(button, INPUT);
}
void loop() {
 buttonState=digitalRead(button); 
 if (buttonState == 1)
 {
 digitalWrite(ledpin, HIGH); 
 delay(200);
 }
 if (buttonState==0)
 {
 digitalWrite(ledpin, LOW); 
 delay(200);
 }
}

RPi_ledtest

Python
Simple program to check led and button with RPi
import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_UP)  #Button to GPIO23
GPIO.setup(24, GPIO.OUT)  #LED to GPIO24

try:
    while True:
         button_state = GPIO.input(23)
         if button_state == False:
             GPIO.output(24, True)
             print('Button Pressed ')
             time.sleep(0.2)
         else:
             GPIO.output(24, False)
except:
    GPIO.cleanup()

RPi_led

Python
Main script
import time 
import RPi.GPIO as GPIO 
import paho.mqtt.client as mqtt 
# Configuration: 
LED_PIN        = 24 
BUTTON_PIN     = 23 
# Initialize GPIO for LED and button. 
GPIO.setmode(GPIO.BCM) 
GPIO.setwarnings(False) 
GPIO.setup(LED_PIN, GPIO.OUT) 
GPIO.output(LED_PIN, GPIO.LOW) 
GPIO.setup(BUTTON_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP) 
# Setup callback functions that are called when MQTT events happen like 
# connecting to the server or receiving data from a subscribed feed. 
def on_connect(client, userdata, flags, rc): 
   print("Connected with result code " + str(rc)) 
   # Subscribing in on_connect() means that if we lose the connection and 
   # reconnect then subscriptions will be renewed. 
   client.subscribe("/leds/pi") 
# The callback for when a PUBLISH message is received from the server. 
def on_message(client, userdata, msg): 
   print(msg.topic+" "+str( msg.payload)) 
   # Check if this is a message for the Pi LED. 
   if msg.topic == '/leds/pi': 
       # Look at the message data and perform the appropriate action. 
       if msg.payload == b'ON': 
           GPIO.output(LED_PIN, GPIO.HIGH) 
       elif msg.payload == b'OFF': 
           GPIO.output(LED_PIN, GPIO.LOW) 
       elif msg.payload == b'TOGGLE': 
           GPIO.output(LED_PIN, not GPIO.input(LED_PIN)) 
# Create MQTT client and connect to localhost, i.e. the Raspberry Pi running 
# this script and the MQTT server. 
client = mqtt.Client() 
client.on_connect = on_connect 
client.on_message = on_message 
client.connect('localhost', 1883, 60) 
# Connect to the MQTT server and process messages in a background thread. 
client.loop_start() 
# Main loop to listen for button presses. 
print('Script is running, press Ctrl-C to quit...') 
while True: 
   # Look for a change from high to low value on the button input to 
   # signal a button press. 
   button_first = GPIO.input(BUTTON_PIN) 
   time.sleep(0.02)  # Delay for about 20 milliseconds to debounce. 
   button_second = GPIO.input(BUTTON_PIN) 
   if button_first == GPIO.HIGH and button_second == GPIO.LOW: 
       print('Button pressed!') 
       # Send a toggle message to the ESP8266 LED topic. 
       client.publish('/leds/esp8266', 'TOGGLE')

Credits

Ruchir Sharma

Ruchir Sharma

12 projects • 180 followers

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Related channels and tags
  • Espressif
  • NodeMCU
  • Raspberry Pi
  • SparkFun