Control a RC car using Node-Red GUI and HiveMQ broker on PicoW

 Node-Red Flow

The cyan node is button node from Dashboard 2.0 which needs to be installed in node-red additionally as it is a 3rd party app. The pink node is mqtt out node.

HiveMQ

Take all the cluster details from HiveMQ to be put in mqtt out node

Node-Red Button node settings

Change the payload value for Left, Right, Front, Back and Stop Button to L, R, F, B & S value and select the type to be string

Node-Red mqtt out node settings

Click on the pencil button to set the broker settings

First you need to arrange the buttons on the dashboard so that it intuitively can tell which button to press. so we need to rearrange the layout so that the buttons look like below on http://localhost:1880/dashboard

In Dasboard 2.0 under pages hover mouse on the page . For me it is Garden , when i hover my mouse there appears a pencil shaped button . Click on it to go to layout editor

Make the buttons 1x1 size and add spacer as shown in the layout below and save the layout.

Testing connection and messaging between NodeRed and HiveMQ

Open HiveMQ and go to Web Client tab add the credentials and login. Under Topic Subscriptions add # to subscribe to all the topics 

Now open the node-red dashboard from url http://localhost:1880/dashboard/

Click on one of the buttons say front button we should see F in Messages on the Right side 

Now the Micropython Code for PicoW is as follows(Modified from Random Nerd Tutorials). Just for simulation LEDs are connected on GP8, GP15, GP16 & GP20 Pins.

Micropython Code

# Rui Santos & Sara Santos - Random Nerd Tutorials

# Complete project details at https://RandomNerdTutorials.com/raspberry-pi-pico-w-mqtt-micropython/

from machine import Pin

from time import sleep

import network

from umqtt.simple import MQTTClient

import config

# Define LED

led = Pin('LED', Pin.OUT)

led1 = Pin(8, Pin.OUT)

led2 = Pin(15, Pin.OUT)

led3 = Pin(16, Pin.OUT)

led4 = Pin(20, Pin.OUT)

# Constants for MQTT Topics

MQTT_TOPIC_LED = 'car/dir'

# MQTT Parameters

MQTT_SERVER = config.mqtt_server

MQTT_PORT = 0

MQTT_USER = config.mqtt_username

MQTT_PASSWORD = config.mqtt_password

MQTT_CLIENT_ID = b'raspberrypi_picow'

MQTT_KEEPALIVE = 7200

MQTT_SSL = True   # set to False if using local Mosquitto MQTT broker

MQTT_SSL_PARAMS = {'server_hostname': MQTT_SERVER}

# Init Wi-Fi Interface

def initialize_wifi(ssid, password):

    wlan = network.WLAN(network.STA_IF)

    wlan.active(True)

    # Connect to the network

    wlan.connect(ssid, password)

    # Wait for Wi-Fi connection

    connection_timeout = 10

    while connection_timeout > 0:

        if wlan.status() >= 3:

            break

        connection_timeout -= 1

        print('Waiting for Wi-Fi connection...')

        sleep(1)

    # Check if connection is successful

    if wlan.status() != 3:

        return False

    else:

        print('Connection successful!')

        network_info = wlan.ifconfig()

        print('IP address:', network_info[0])

        return True

# Connect to MQTT Broker

def connect_mqtt():

    try:

        client = MQTTClient(client_id=MQTT_CLIENT_ID,

                            server=MQTT_SERVER,

                            port=MQTT_PORT,

                            user=MQTT_USER,

                            password=MQTT_PASSWORD,

                            keepalive=MQTT_KEEPALIVE,

                            ssl=MQTT_SSL,

                            ssl_params=MQTT_SSL_PARAMS)

        client.connect()

        return client

    except Exception as e:

        print('Error connecting to MQTT:', e)

# Subcribe to MQTT topics

def subscribe(client, topic):

    client.subscribe(topic)

    print('Subscribe to topic:', topic)

    

# Callback function that runs when you receive a message on subscribed topic

def my_callback(topic, message):

    # Perform desired actions based on the subscribed topic and response

    print('Received message on topic:', topic)

    print('Response:', message)

    # Check the content of the received message

    if message == b'F':

        print('Turning Car FRONT')

        led1.value(1)  # Turn LED ON

        led2.value(0)

        led3.value(0)

        led4.value(0)

    elif message == b'L':

        print('Turning Car Left')

        led1.value(0)  # Turn LED ON

        led2.value(1)

        led3.value(0)

        led4.value(0)  

    elif message == b'R':

        print('Turning Car Right')

        led1.value(0)  # Turn LED ON

        led2.value(0)

        led3.value(1)

        led4.value(0)

    elif message == b'B':

        print('Turning Car Back')

        led1.value(0)  # Turn LED ON

        led2.value(0)

        led3.value(0)

        led4.value(1)

    elif message == b'S':

        print('Stopping Car')

        led1.value(0)  # Turn LED ON

        led2.value(0)

        led3.value(0)

        led4.value(0)

    else:

        print('Unknown command')

    

try:

    # Initialize Wi-Fi

    if not initialize_wifi(config.wifi_ssid, config.wifi_password):

        print('Error connecting to the network... exiting program')

    else:

        # Connect to MQTT broker, start MQTT client

        client = connect_mqtt()

        client.set_callback(my_callback)

        subscribe(client, MQTT_TOPIC_LED)

        

        # Continuously checking for messages

        while True:

            sleep(1)

            client.check_msg()

            print('Loop running')

except Exception as e:

    print('Error:', e)