Sensor Network with Micropython For Home Assistant

Home Assistant OS has become one of the people choice for open source smart home management software. It is supported by many other open source hardware and software. But there is one software that sometimes could be difficult to connect to Home Assistant, it is Micropython.

In this project page I will guide you to connect the PSoC™ 6 Wi-Fi BT Prototyping Kit: CY8CPROTO-062-4343W with micropython firmware to Home Assistant OS.

Preparation

Before going further, make sure you already have a device that already running the Home Assistant OS. If you are new to home assistant, there are a bunch of guide on youtube regarding the installation or you can visit the home assistant documentation if you preferred a written documentation.

On the hardware side follow along this guide to install micropython firmware on the PSoC™ 6 Wi-Fi BT Prototyping Kit: CY8CPROTO-062-4343W.

After the micropython is installed, switch the jumper pin on the CY8CPROTO-062-4343W like the picture below.

this step is important because it will give 3.3 v power needed for the external sensor.

Download thonny IDE and install it. After thonny is installed open the Application the choose the serial port from CY8CPROTO-062-4343W like the picture below

If everything run accordingly your thonny IDE should be look like this

Add on and Library Support

In order to receive the data from the CY8CPROTO-062-4343W to the Home Assistant OS we are gonna use the MQTT protocol.

To get MQTT on Home Assistant you need to install the MQTT/mosquitto broker add on. Click setting

type mqtt on the seacrh bar the click install

On the hardware side open this link and paste it on the thonny IDE then save it as "umqttsimple.py" on the root of the micropython drive

For this project I am gonna use the BMP280 as test sensor. In order to use the BMP280 for micropython grab the library here and do the same thing like the step above

After all those is setup now we are ready to go to the next step

Configuration and Testing

On the Home Assistant setting open file/package manager open the configuration.yaml file and paste the code below

# Example configuration.yaml entry
mqtt:
  - sensor:
      name: "Temperature"
      unique_id: "temp1"
      state_topic: "homeassistant/office/temperature"
      unit_of_measurement: "C"
      value_template: "{{ value }}"

Back on thonny IDE paste this code below and save it on the root directory

from machine import Pin
import time
from umqttsimple import MQTTClient
import ubinascii
import machine
import micropython
import network

import gc
gc.collect()
last_message = 0
message_interval = 5
counter = 0
ssid = 'XXXXXXXX'
password = 'XXXXXXXX'
mqtt_server = 'xxx.xxx.xxx.xxx'  #Replace with your MQTT Broker IP
mqtt_port = 1883
client_id = ubinascii.hexlify(machine.unique_id())
print(client_id)
topic_sub = b'homeassistant/office/temperature'
topic_pub = b'homeassistant/office/temperature'
user = b'homeassistant'
password1 = b'xxxxxxxxxxxxxxx'

station = network.WLAN(network.STA_IF)
station.active(True)
station.connect(ssid, password)

while station.isconnected() == False:
  pass

print('Connection successful')
print(station.ifconfig())


def sub_cb(topic, msg):
  print((topic, msg))
  if topic == b'notification' and msg == b'received':
    print('ESP received hello message')

def connect_and_subscribe():
  global client_id, mqtt_server, topic_sub
  client = MQTTClient(client_id, mqtt_server, mqtt_port, user, password1)
  client.set_callback(sub_cb)
  client.connect()
  client.subscribe(topic_sub)
  print('Connected to %s MQTT broker, subscribed to %s topic' % (mqtt_server, topic_sub))
  return client

def restart_and_reconnect():
  print('Failed to connect to MQTT broker. Reconnecting...')
  time.sleep(10)
  machine.reset()

try:
  client = connect_and_subscribe()
except OSError as e:
  restart_and_reconnect()

while True:
  try:
    client.check_msg()
    if (time.time() - last_message) > message_interval:
      msg = str(counter)
      client.publish(topic_pub, msg)
      last_message = time.time()
      counter += 1
  except OSError as e:
    restart_and_reconnect()

change the wifi configuration accordingly and mqtt server IP based on your home assistant IP address and then run it. If everything run accordingly the you will the result like below

this means that your hardware has successfully make an mqtt communication to the home assistant OS.

to display the data from the hardware, Open the Home Assistant Dashboard and click the edit button

[pic here]

click add card and choose the mqtt device

choose gauge and search for temperature entity

then you will see the same data send from the hardware displayed on the Home Assistant Dashboard

Wiring the sensor

The BMP280 sensor is using I2C interfaces and I already try the built in Hardware I2C library from the firmware but it doesn't. Thankfully when I try the SoftI2C library I can get the sensor reading successfully. This means SDA and SCL pin could be configured with any pin on the CY8CPROTO-062-4343W hardware.

But for this project I am gonna use the configuration like the picture below

PSOC 6 BMP280

VDD USB <------------> VCC

GND <------------> GND

P6.0 <------------> SCL

P6.1 <------------> SDA

To test the sensor upload the code below

from machine import Pin,SoftI2C
from bmp280 import *
import time

bus = SoftI2C(scl='P6_0', sda='P6_1', freq=100000)
bmp = BMP280(bus)

bmp.use_case(BMP280_CASE_INDOOR)

while True:
    pressure=bmp.pressure
    p_bar=pressure/100000
    p_mmHg=pressure/133.3224
    temperature=bmp.temperature
    print("Temperature: {} C".format(temperature))
    print("Pressure: {} Pa, {} bar, {} mmHg".format(pressure,p_bar,p_mmHg))
    time.sleep(1)

Run the code then you will be presented with result like the picture below

Sending Sensor Data

Now after testing and everything is prepared, we are ready the send the sensor data the home assistant Dashboard. Simply upload the code below and run it on your thonny IDE, don't forget to change the wifi and mqtt configuration according to your configuration

from machine import Pin,SoftI2C
import time
from umqttsimple import MQTTClient
import ubinascii
import machine
import micropython
import network
from bmp280 import *
import gc
gc.collect()
last_message = 0
message_interval = 5
counter = 0

bus = SoftI2C(scl='P6_0', sda='P6_1', freq=100000)
bmp = BMP280(bus)

bmp.use_case(BMP280_CASE_INDOOR)

ssid = 'xxxxxxx'
password = 'xxxxxx'
mqtt_server = 'xxx.xxx.xxx.xxx'  #Replace with your MQTT Broker IP
mqtt_port = 1883
client_id = ubinascii.hexlify(machine.unique_id())
print(client_id)
topic_sub = b'homeassistant/office/temperature'
topic_pub = b'homeassistant/office/temperature'
user = b'homeassistant'
password1 = b'xxxxxxxxxxxxx'

station = network.WLAN(network.STA_IF)
station.active(True)
station.connect(ssid, password)

while station.isconnected() == False:
  pass

print('Connection successful')
print(station.ifconfig())


def sub_cb(topic, msg):
  print((topic, msg))
  if topic == b'notification' and msg == b'received':
    print('ESP received hello message')

def connect_and_subscribe():
  global client_id, mqtt_server, topic_sub
  client = MQTTClient(client_id, mqtt_server, mqtt_port, user, password1)
  client.set_callback(sub_cb)
  client.connect()
  client.subscribe(topic_sub)
  print('Connected to %s MQTT broker, subscribed to %s topic' % (mqtt_server, topic_sub))
  return client

def restart_and_reconnect():
  print('Failed to connect to MQTT broker. Reconnecting...')
  time.sleep(10)
  machine.reset()

try:
  client = connect_and_subscribe()
except OSError as e:
  restart_and_reconnect()

while True:
  try:
    client.check_msg()
    temperature=bmp.temperature
    if (time.time() - last_message) > message_interval:
      msg = str(temperature)
      client.publish(topic_pub, msg)
      last_message = time.time()
      counter += 1
  except OSError as e:
    restart_and_reconnect()

and congratulation, now you can add any sensor using micropython to the Home Assistant OS

Future Development

With this project as a base project, I will try to developed a custom home assistant mqtt library for micropython So everyone could easily attach a sensor do minimum coding to send sensor data to Home Assistant OS