How To Build an Air Quality Alert Light with Raspberry Pi Pico

Air quality is a big concern. We take the air that we breathe for granted, and sometimes that air is full of pollution. Forest fires in Canada and hill fires in the United Kingdom are all recent examples of fire polluting our air, so how can we check that it is safe to go out?

In this how to we’ll build a project that uses air quality data from the OpenWeather API to give us an indication of air quality before we leave home. The data is visualized using a Raspberry Pi Pico W, a $6 microcontroller that can go online, get the data and then display the data using a strip of NeoPixel RGB LEDs.

The circuit is made up of two sections. The input and the output. The input is a simple push button connected to GPIO14 and to the 3V3 pin of the Pico W. The normal state of GPIO14 is pulled down to Ground, essentially 0V. When we press the button we connect the 3V3 pin to GPIO14, causing it to pull the pin high (to 3.3V). This change of state is what our code looks for. The output is a NeoPixel strip connected to 3V3, GND and GPIO16. GPIO16 is used to send data to the NeoPixels, changing their color as required.

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import network
import time
import urequests
from machine import Pin
from neopixel import Neopixel

button = Pin(14, Pin.IN, Pin.PULL_DOWN)

pixels = Neopixel(8, 0, 16, "GRB")

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("SSID", "PASSWORD")
time.sleep(5)

print(wlan.isconnected())

if wlan.isconnected() == True:
   for i in range(10):
       pixels.fill((0, 64, 0))
       pixels.show()
       time.sleep(0.1)
       pixels.fill((0, 0, 0))
       pixels.show()
       time.sleep(0.1)

else:
       for i in range(10):
           pixels.fill((64, 0, 0))
           pixels.show()
           time.sleep(0.1)
           pixels.fill((0, 0 , 0))
           pixels.show()
           time.sleep(0.1)

while True:
   if button.value():

13. Create an object, aq, and store the latest air quality data. Pressing the button triggers the code to download the latest air pollution data from OpenWeather using a free API key. Note that you will have to sign up for a free account, then click on your username and select My API Keys. Generate a new API key called AirPollution. Copy the API key and replace it in the URL below. Also change the lat (latitude) and lon (longitude) to match your location. This can be found via Google Maps, ours is set to New York City.

       aq = urequests.get("http://api.openweathermap.org/data/2.5/air_pollution/forecast?lat=40.714272&lon=-74.005966&appid=YOUR API KEY HERE").json()

       air_quality_index = aq['list'][0]['main']['aqi']

       print("The Air Quality index is: ",str(air_quality_index))

       if air_quality_index == 1:
           for i in range(10):
               pixels.fill((0, 64, 0))
               pixels.show()
               time.sleep(0.5)
               pixels.fill((0, 0, 0))
               pixels.show()
               time.sleep(0.5)

       elif air_quality_index == 2:
           for i in range(10):
               pixels.fill((51,255,255))
               pixels.show()
               time.sleep(0.5)
               pixels.fill((0, 0, 0))
               pixels.show()
               time.sleep(0.5)

       elif air_quality_index == 3:
           for i in range(10):
               pixels.fill((153, 51, 255))
               pixels.show()
               time.sleep(0.5)
               pixels.fill((0, 0, 0))
               pixels.show()
               time.sleep(0.5)

       elif air_quality_index == 4:
           for i in range(10):
               pixels.fill((255,153,51))
               pixels.show()
               time.sleep(0.5)
               pixels.fill((0, 0, 0))
               pixels.show()
               time.sleep(0.5)

       elif air_quality_index == 5:
           for i in range(10):
               pixels.fill((255, 0, 0))
               pixels.show()
               time.sleep(0.5)
               pixels.fill((0, 0, 0))
               pixels.show()
               time.sleep(0.5)

       else:
pass

import network
import time
import urequests
from machine import Pin
from neopixel import Neopixel

button = Pin(14, Pin.IN, Pin.PULL_DOWN)
pixels = Neopixel(8, 0, 16, "GRB")

wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("SSID", "PASSWORD")
time.sleep(5)
print(wlan.isconnected())
if wlan.isconnected() == True:
    for i in range(10):
        pixels.fill((0, 64, 0))
        pixels.show()
        time.sleep(0.1)
        pixels.fill((0, 0, 0))
        pixels.show()
        time.sleep(0.1)
else:
        for i in range(10):
            pixels.fill((64, 0, 0))
            pixels.show()
            time.sleep(0.1)
            pixels.fill((0, 0 , 0))
            pixels.show()
            time.sleep(0.1)
while True:
    if button.value():
        aq = urequests.get("http://api.openweathermap.org/data/2.5/air_pollution/forecast?lat=40.714272&lon=-74.005966&appid=YOUR API KEY HERE").json()
        air_quality_index = aq['list'][0]['main']['aqi']
        print("The Air Quality index is: ",str(air_quality_index))
        if air_quality_index == 1:
            for i in range(10):
                pixels.fill((0, 64, 0))
                pixels.show()
                time.sleep(0.5)
                pixels.fill((0, 0, 0))
                pixels.show()
                time.sleep(0.5)
        elif air_quality_index == 2:
            for i in range(10):
                pixels.fill((51,255,255))
                pixels.show()
                time.sleep(0.5)
                pixels.fill((0, 0, 0))
                pixels.show()
                time.sleep(0.5)
        elif air_quality_index == 3:
            for i in range(10):
                pixels.fill((153, 51, 255))
                pixels.show()
                time.sleep(0.5)
                pixels.fill((0, 0, 0))
                pixels.show()
                time.sleep(0.5)
        elif air_quality_index == 4:
            for i in range(10):
                pixels.fill((255,153,51))
                pixels.show()
                time.sleep(0.5)
                pixels.fill((0, 0, 0))
                pixels.show()
                time.sleep(0.5)
        elif air_quality_index == 5:
            for i in range(10):
                pixels.fill((255, 0, 0))
                pixels.show()
                time.sleep(0.5)
                pixels.fill((0, 0, 0))
                pixels.show()
                time.sleep(0.5)
        else:
            pass

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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".

3 Comments Comment from the forums

domih

Thank you, Mr Pounder.
Reply
Kind reminds me of this old project we did in uni by using the SDS011 sensor. For monitoring PM2.5/PM10 data.

https://www.raspberrypi.com/news/monitor-air-quality-with-a-raspberry-pi/
Reply
1_rick

For advanced usage, switch to C++ (I know CircuitPython can't put the processor into and out of sleep mode, and I assume MicroPython can't either, otherwise I'd say stick with MP) and sleep the mcu, using an interrupt on the button press to wake it up, do the activity, and put it back to sleep. Then you can run it for ages on a battery.
Reply

How To Build an Air Quality Alert Light with Raspberry Pi Pico

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