How to Use Raspberry Pi Pico W With Node-RED

Node-Red Pico W — (Image credit: Tom's Hardware)

In a previous how to, we introduced MQTT (Message Query Telemetry Transport) with the $6 Raspberry Pi Pico W. In that tutorial we kept things relatively simple. Publishing and subscribing to messages using a little MicroPython and an MQTT broker. We then used an online MQTT service to interact with the Pico W. This proved that everything worked, but in this how-to, we are going to kick things up a notch and build a web application using very little code.

In this how to, we will use Node-RED, an event driven programming language that uses nodes (blocks) to create flows (algorithms) that will subscribe to a live MQTT data feed from our Raspberry Pi Pico W and use that data to create real-time charts and gauges in a web application.

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import network
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("Wi-Fi AP","PASSWORD")

import upip

upip.install(‘umqtt.simple’)

import network
import time
from breakout_bme68x import BreakoutBME68X, STATUS_HEATER_STABLE
from pimoroni_i2c import PimoroniI2C
from umqtt.simple import MQTTClient

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("Wi-Fi AP","PASSWORD")

PINS_BREAKOUT_GARDEN = {"sda": 4, "scl": 5}

i2c = PimoroniI2C(**PINS_BREAKOUT_GARDEN)

bmp = BreakoutBME68X(i2c, 0x77)

mqtt_server = 'broker.hivemq.com'
client_id = 'bigles'
topic_pub_temp = b'TomsHardware/Temp'
topic_pub_humid = b'TomsHardware/Humidity'

def mqtt_connect():

   client = MQTTClient(client_id, mqtt_server, keepalive=3600)

   client.connect()

   print('Connected to %s MQTT Broker'%(mqtt_server))
   return client

def reconnect():
   print('Failed to connect to the MQTT Broker. Reconnecting...')
   time.sleep(5)
   machine.reset()

try:
   client = mqtt_connect()

except OSError as e:
   reconnect()

while True:

   temperature, pressure, humidity, gas, status, _, _ = bmp.read()

heater = "Stable" if status & STATUS_HEATER_STABLE else "Unstable"

print("{:0.2f}c, {:0.2f}Pa, {:0.2f}%, {:0.2f} Ohms, Heater: {}".format(
       temperature, pressure, humidity, gas, heater))

   temperature = round(temperature,1)
   humidity = round(humidity,1)

   client.publish(topic_pub_temp, str(temperature))
   client.publish(topic_pub_humid, str(humidity))

   time.sleep(5.0)

import network
import time
from breakout_bme68x import BreakoutBME68X, STATUS_HEATER_STABLE
from pimoroni_i2c import PimoroniI2C
from umqtt.simple import MQTTClient
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("Wi-Fi AP","PASSWORD")
PINS_BREAKOUT_GARDEN = {"sda": 4, "scl": 5}
i2c = PimoroniI2C(**PINS_BREAKOUT_GARDEN)
bmp = BreakoutBME68X(i2c, 0x77)
mqtt_server = 'broker.hivemq.com'
client_id = 'bigles'
topic_pub_temp = b'TomsHardware/Temp'
topic_pub_humid = b'TomsHardware/Humidity'
def mqtt_connect():
   client = MQTTClient(client_id, mqtt_server, keepalive=3600)
   client.connect()
   print('Connected to %s MQTT Broker'%(mqtt_server))
   return client
def reconnect():
   print('Failed to connect to the MQTT Broker. Reconnecting...')
   time.sleep(5)
   machine.reset()
try:
   client = mqtt_connect()
except OSError as e:
   reconnect()    
while True:
   temperature, pressure, humidity, gas, status, _, _ = bmp.read()
   heater = "Stable" if status & STATUS_HEATER_STABLE else "Unstable"
   print("{:0.2f}c, {:0.2f}Pa, {:0.2f}%, {:0.2f} Ohms, Heater: {}".format(
       temperature, pressure, humidity, gas, heater))
   temperature = round(temperature,1)
   humidity = round(humidity,1)
   client.publish(topic_pub_temp, str(temperature))
   client.publish(topic_pub_humid, str(humidity))
time.sleep(5.0)

bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)

sudo systemctl enable nodered.service

raspberrypi.local:1880

The project is now complete. Our Raspberry Pi Pico W has been set to automatically connect to our Wi-Fi, publish data over MQTT. Our Raspberry Pi 4 running Node-RED is interpreting the MQTT data into a live dashboard, keeping us informed of the temperature and humidity in our home. Node-RED will auto-start when the Raspberry Pi boots, creating an appliance, ready to serve data at a moment's notice.

Les Pounder is an associate editor at Tom's Hardware. He is a creative technologist and for seven years has created projects to educate and inspire minds both young and old. He has worked with the Raspberry Pi Foundation to write and deliver their teacher training program "Picademy".

1 Comment Comment from the forums

TerryYoung2003

Do you HAVE to send the data to the cloud if the devices are both on the same local WiFi network?
I wanted to use this type of thing to have Pico Ws read various boat sensors (tank levels, temps and stuff) and send that data to a central Raspberry Pi 4. The issue with how you have this is that when we're out sailing, we're often out of cell range, so the cloud isn't an option.
Given that I can already send simple data from the Pico W via a self-generated webpage, I was wondering if it could be streamed via maybe a particular IP : Port straight to Node Red on the central Pi 4, which is already reading marine NMEA data and sending it out over WiFi using Signal K.
Reply

Raspberry Pi Pico W GPIO	Color
3v3(OUT)	Red
GND	Black
SDA (GP4)	Blue
SCL (GP5)	Yellow

How to Use Raspberry Pi Pico W With Node-RED

For this project you will need

Connecting the BME688 Sensor to the Raspberry Pi Pico W

Setting up the Raspberry Pi Pico W

Publishing Sensor Data to MQTT

Complete MQTT Publish Code Listing

Subscribing to the Sensor Data with Node-RED

Adding Humidity Data