Raspberry Pi Pico W MicroPython MQTT Tutorial | Control LED using MQTT Node Red

MQTT_PICO_W.py

import network
from umqtt.simple import MQTTClient
import time
import machine

MQTT_BROKER="YOUR_SYSTEM_IP"
MQTT_PORT = 1883
MQTT_CLIENT_ID="pico_client"

led_green = machine.Pin(0, machine.Pin.OUT)
led_red = machine.Pin(1, machine.Pin.OUT)

#subscribe topics
sub_topic_red_led="led_red/topic"
sub_topic_green_led="led_green/topic"

#publish topic
pub_topic_temperature = "temperature/topic"


# Connect to the WiFi

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("YOUR_SSID", "YOUR_PASSWORD")

while not wlan.isconnected():
    time.sleep(1)
    
print("Connected to the WiFi")

def callback(topic, msg):
    sub_msg = msg.decode('utf-8')
    sub_topic =topic.decode('utf-8')
    print("Received message - ", sub_msg , "on topic - ",sub_topic)
    
    # if led_red == led_red
    if sub_topic == sub_topic_red_led: 
        led_red.value(int(sub_msg))
    elif sub_topic == sub_topic_green_led:
        led_green.value(int(sub_msg))

mqtt_client = MQTTClient(client_id=MQTT_CLIENT_ID, server=MQTT_BROKER, port=MQTT_PORT)
mqtt_client.set_callback(callback)
mqtt_client.connect()
print("Connected to MQTT broker")

mqtt_client.subscribe(sub_topic_red_led)
mqtt_client.subscribe(sub_topic_green_led)

def read_temperature():
    adc = machine.ADC(4)  # Use ADC pin GP4
    conversion_factor = 3.3 / (65535)  # ADC conversion factor
    sensor_value = adc.read_u16() * conversion_factor
    temperature = 27 - (sensor_value - 0.706) / 0.001721  # Convert sensor value to temperature (formula may vary)
    return temperature

try:
    while True:
        mqtt_client.check_msg()
        
        temperature = read_temperature()
        temp_str = str(temperature)
        mqtt_client.publish(pub_topic_temperature,temp_str.encode('utf-8'))
        print('Temp published',temperature)
        
        time.sleep(2)
        
except KeyboardInterrupt:
    print('Disconnected!')
    mqtt_client.disconnect()