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

# === Configuration ===
WIFI_SSID = 'your_wifi_ssid'
WIFI_PASSWORD = 'your_wifi_password'

MQTT_BROKER = 'mqtt_broker_address'  # e.g., 'broker.hivemq.com'
MQTT_PORT = 1883  # Default MQTT port
MQTT_TOPIC_SUB = 'your/subscription/topic'  # Topic to subscribe to
MQTT_CLIENT_ID = 'pico-w-client'

LED_PIN = 25  # Onboard LED for Pico W. Change if using external LED.

# ======================

# Initialize LED
led = machine.Pin(LED_PIN, machine.Pin.OUT)
led.value(0)  # Turn LED off initially

message_received = False  # Flag to indicate message reception

def connect_wifi(ssid, password):
    """Connects to the specified Wi-Fi network."""
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    if not wlan.isconnected():
        print('Connecting to network...')
        wlan.connect(ssid, password)
        # Wait until connected
        while not wlan.isconnected():
            time.sleep(0.5)
    print('Network connected:', wlan.ifconfig())

def on_message(topic, msg):
    """Callback function when a message is received."""
    global message_received
    print('Received message on topic {}: {}'.format(topic.decode(), msg.decode()))
    message_received = True

def main():
    global message_received

    # Connect to Wi-Fi
    connect_wifi(WIFI_SSID, WIFI_PASSWORD)

    # Initialize MQTT client
    client = MQTTClient(MQTT_CLIENT_ID, MQTT_BROKER, port=MQTT_PORT)
    client.set_callback(on_message)
    try:
        client.connect()
    except Exception as e:
        print('Failed to connect to MQTT broker:', e)
        return

    print('Connected to MQTT broker at {}'.format(MQTT_BROKER))
    client.subscribe(MQTT_TOPIC_SUB)
    print('Subscribed to topic:', MQTT_TOPIC_SUB)

    try:
        while True:
            # Blink LED to indicate polling
            led.on()
            time.sleep(0.1)
            led.off()
            time.sleep(0.1)

            # Check for new MQTT messages (non-blocking)
            try:
                client.check_msg()
            except OSError as e:
                print('Lost connection to MQTT broker. Reconnecting...')
                try:
                    client.connect()
                    client.subscribe(MQTT_TOPIC_SUB)
                    print('Reconnected and resubscribed to topic.')
                except Exception as e:
                    print('Reconnection failed:', e)
                    time.sleep(5)
                    continue  # Retry after delay

            # If a message was received, set LED solid for 1 second
            if message_received:
                led.on()
                time.sleep(1)
                led.off()
                message_received = False

    except KeyboardInterrupt:
        print('Interrupted by user')
    finally:
        client.disconnect()
        print('Disconnected from MQTT broker')

if __name__ == '__main__':
    main()

mosquitto_pub -h mqtt_broker_address -t your/subscription/topic -m "Hello Pico W"

import network
import time
from machine import Pin
try:
    from umqtt.simple import MQTTClient
except ImportError:
    # If umqtt.simple is not available, try umqtt.robust
    from umqtt.robust import MQTTClient

# --------------------------- Configuration ---------------------------

# Wi-Fi credentials
WIFI_SSID = 'your_wifi_ssid'
WIFI_PASSWORD = 'your_wifi_password'

# MQTT Broker configuration
MQTT_BROKER = 'broker.hivemq.com'  # Replace with your MQTT broker address
MQTT_PORT = 1883  # Default MQTT port (change if necessary)
MQTT_TOPIC = b'your/topic'  # Replace with your desired topic
CLIENT_ID = 'pico_w_zero_client'  # Unique client ID

# LED configuration
LED_PIN = 25  # Onboard LED pin for Raspberry Pi Pico W

# --------------------------- Functions ---------------------------

def connect_wifi(ssid, password):
    """Connect to the specified Wi-Fi network."""
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    
    if not wlan.isconnected():
        print('Connecting to Wi-Fi...')
        wlan.connect(ssid, password)
        while not wlan.isconnected():
            print('.', end='')
            time.sleep(0.5)
    print('\nConnected to Wi-Fi:', wlan.ifconfig())

def mqtt_callback(topic, msg):
    """Callback function that is called when a message is received."""
    print(f'Received message on topic {topic.decode()}: {msg.decode()}')
    
    # Set LED solid
    led.on()
    
    # Keep LED on for 1 second
    time.sleep(1)
    
    # Turn LED off to resume blinking
    led.off()

def reconnect(client):
    """Reconnect to MQTT broker and resubscribe to topic."""
    print('Reconnecting to MQTT broker...')
    client.disconnect()
    client.connect()
    client.subscribe(MQTT_TOPIC)
    print('Re-subscribed to topic:', MQTT_TOPIC.decode())

# --------------------------- Main Program ---------------------------

# Initialize LED
led = Pin(LED_PIN, Pin.OUT)
led.off()  # Ensure LED is off initially

# Connect to Wi-Fi
connect_wifi(WIFI_SSID, WIFI_PASSWORD)

# Initialize MQTT client
client = MQTTClient(CLIENT_ID, MQTT_BROKER, port=MQTT_PORT)
client.set_callback(mqtt_callback)

try:
    client.connect()
    print('Connected to MQTT broker:', MQTT_BROKER)
except Exception as e:
    print('Failed to connect to MQTT broker:', e)
    machine.reset()

client.subscribe(MQTT_TOPIC)
print('Subscribed to topic:', MQTT_TOPIC.decode())

try:
    while True:
        # Blink LED to indicate polling
        led.toggle()
        
        # Check for incoming MQTT messages
        try:
            client.check_msg()  # Non-blocking
        except OSError as e:
            print('MQTT connection error:', e)
            reconnect(client)
        
        # Delay to make LED blink visible
        time.sleep(0.5)
        
except KeyboardInterrupt:
    # Gracefully disconnect on interrupt
    print('Disconnecting...')
    client.disconnect()
    led.off()