LED

Overview

This section focuses on adding an LED to Home Assistant for on/off control. For easy demonstration, this tutorial uses both the WalnutPi 1B and the WalnutPi PicoW (ESP32S3) as MQTT nodes to operate.

WalnutPi 1B LED

led

WalnutPi PicoW LED

led

Objective

Add an LED to the WalnutPi Home Assistant host and implement on/off control.

Explanation

An LED can be thought of as a single-color light fixture, using the light component from the Home Assistant MQTT integration. The key to the experiment is understanding the topic information for discovering MQTT devices and the control method, as detailed below:

MQTT Topic

The following topic is used for the Home Assistant host to discover this device via MQTT:

homeassistant/light/1b_led/config

homeassistant: Default prefix
light: The MQTT component used for LEDs is light
1b_led: Entity ID, must be unique. This is a custom value representing the WalnutPi 1B's LED;
config: Default suffix

MQTT Payload

{
    "name":"led",
    "device_class":"LIGHT",
    "command_topic":"1b_led/light/state",
    "unique_id":"1b_led",

    "device":{
                "identifiers":"1b_01",
                "name":"WalnutPi_1B"
            }
}

Entity

"name":"led": Entity name, can be customized;
"device_class":"LIGHT": Component type, related to the topic configuration above. Must not be wrong. For example, LIGHT here is a valid entity under the light component;
"command_topic":"1b_led/light/state": Used to publish relevant attribute topics after registering the entity, such as the on/off state of a light. Can be customized; just make sure different entities have different topics;
"unique_id":"1b_led": Entity ID, can be customized, must be unique for each entity;

Device

Informs Home Assistant of the device corresponding to the entity.

"identifiers":"1b_01": Identification identifier, unique per device;
"name":"WalnutPi_1B": Device name, can be customized;

For more MQTT light content, see the official documentation: https://www.home-assistant.io/integrations/light.mqtt/

The code flow is as follows:

Implementation Using WalnutPi 2B

The WalnutPi 2B has an onboard programmable LED. We learned about WalnutPi Python MQTT communication in a previous tutorial MQTT Communication. We build on that foundation:

Reference Code

'''
Experiment Name: Home Assistant LED Light
Platform: WalnutPi
Description: Program Home Assistant LED light control.
'''

#Import libraries
import paho.mqtt.client as mqtt

import board
from digitalio import DigitalInOut, Direction

#Build LED object and initialize
led = DigitalInOut(board.LED) #Define pin
led.direction = Direction.OUTPUT  #IO as output

led.value = 0 #Output low level, turn off blue LED

#MQTT server and user info
CLIENT_ID = 'WalnutPi-LED' # Client ID
SERVER = '127.0.0.1' #Localhost IP address
PORT = 1883
USER='pi'
PASSWORD='pi'

#Build MQTT client object
client = mqtt.Client(CLIENT_ID)

#Configure username and password
client.username_pw_set(USER, PASSWORD)

topic = "picow1/light/led/state"

#Callback executed when client receives a CONNACK response from the server
def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))
    # Subscribing in on_connect() means if we lose connection and reconnect, subscriptions will be renewed.
    client.subscribe("1b_led/light/state")

# Callback executed when a published message is received from the server
def on_message(client, userdata, msg):

    print(msg.topic+" "+str(msg.payload)) #Print topic and payload

    if msg.payload == b'ON' : #Turn on LED

        led.value = 1

    if msg.payload == b'OFF' : #Turn off LED

        led.value = 0

#Configure connection and message callback functions
client.on_connect = on_connect
client.on_message = on_message

#Initiate connection
client.connect(SERVER,PORT)

#Register device on first boot
topic = "homeassistant/light/1b_led/config"
message = """{
           "name":"led",
           "device_class":"LIGHT",
           "command_topic":"1b_led/light/state",
           "unique_id":"1b_led",

           "device":{
                      "identifiers":"1b_01",
                      "name":"WalnutPi_1B"
                    }
            }"""

client.publish(topic, message)

# Start a new thread to maintain MQTT connection.
client.loop_start()

while True:

    pass

Results

Here we use Thonny to remotely run the Python code on the WalnutPi. For methods to run Python code on WalnutPi, see: Running Python Code

led

After running, you can see a new device and entity appear in the Home Assistant host:

led

Click Devices to see device information. On the right, led is the entity. Click the toggle switch to turn the LED on/off:

led

At the same time, MQTT messages are sent to the device:

led

Controlling the WalnutPi 1B LED on/off:

led5

led6

You can also click Add to Dashboard:

led6

Home Assistant automatically selects the card type:

led6

After adding, you can see the device on the Overview dashboard:

led6

Implementation Using WalnutPi PicoW

The WalnutPi PicoW (ESP32-S3) has an onboard programmable LED. For usage, see: WalnutPi PicoW Tutorial. Ensure that both the WalnutPi PicoW and the WalnutPi 2B are connected to the same router:

led6

Reference Code

'''
Experiment Name: Home Assistant LED Light
Platform: WalnutPi + WalnutPi PicoW
Author: WalnutPi
Description: Program Home Assistant LED light control
'''

import network,time
from simple import MQTTClient #Import MQTT module
from machine import Pin,Timer

LED=Pin(46, Pin.OUT) #Initialize WiFi indicator LED

#WiFi connection function
def WIFI_Connect():

    global LED

    wlan = network.WLAN(network.STA_IF) #STA mode
    wlan.active(True)                   #Activate interface
    start_time=time.time()              #Record time for timeout check

    if not wlan.isconnected():
        print('connecting to network...')
        wlan.connect('01Studio', '88888888') #Enter WiFi SSID and password

        while not wlan.isconnected():

            #LED blinking indicator
            LED.value(1)
            time.sleep_ms(300)
            LED.value(0)
            time.sleep_ms(300)

            #Timeout check: if not connected within 15 seconds, treat as timeout
            if time.time()-start_time > 15 :
                print('WIFI Connected Timeout!')
                break

    if wlan.isconnected():
        #Turn on LED
        LED.value(1)

        #Print network info to serial
        print('network information:', wlan.ifconfig())

        return True

    else:
        return False


#Set MQTT callback, executes when a message is received
def MQTT_callback(topic, msg):

    print('topic: {}'.format(topic))
    print('msg: {}'.format(msg))

    if msg == b'ON' :

        LED.value(1)

    if msg == b'OFF' :

        LED.value(0)

#Receive data task
def MQTT_Rev(tim):
    client.check_msg()

#Execute WiFi connection and check if successful
if WIFI_Connect():

    CLIENT_ID = 'WalnutPi-PicoW1' # Client ID
    SERVER = '192.168.1.118'  # MQTT server address
    PORT = 1883
    USER='pi'
    PASSWORD='pi'

    client = MQTTClient(CLIENT_ID, SERVER, PORT, USER, PASSWORD) #Create client object
    client.set_callback(MQTT_callback)  #Configure callback function
    client.connect()

    #Register device
    TOPIC = "homeassistant/light/picow1_led/config"
    mssage = """{
                  "name": "led",
                  "device_class": "LIGHT",
                  "command_topic": "picow1_led/light/state",
                  "unique_id": "picow1_led",

                  "device": {
                            "identifiers": "picow_1",
                            "name": "picow1"
                            }
                }"""

    client.publish(TOPIC, mssage)

    #Subscribe to topic
    TOPIC = 'picow1_led/light/state' # TOPIC name
    client.subscribe(TOPIC) #Subscribe to topic

    #Start RTOS timer, number 1, period 100ms, execute socket receive task
    tim = Timer(1)
    tim.init(period=100, mode=Timer.PERIODIC,callback=MQTT_Rev)

Results

Use Thonny to connect to the WalnutPi PicoW board and run the code above:

led

After a successful connection, you can see one additional device on the WalnutPi Home Assistant host:

led

Enter the device. You can also control the LED on the right and add it to the dashboard:

led

When clicking the switch, the PicoW receives MQTT messages and prints them in the Thonny IDE terminal below. The LED toggles accordingly.

led

LED

Overview​

Objective​

Explanation​

MQTT Topic​

MQTT Payload​

Entity​

Device​

Implementation Using WalnutPi 2B​

Reference Code​

Results​

Implementation Using WalnutPi PicoW​

Reference Code​

Results​

Overview

Objective

Explanation

MQTT Topic

MQTT Payload

Entity

Device

Implementation Using WalnutPi 2B

Reference Code

Results

Implementation Using WalnutPi PicoW

Reference Code

Results