Raspberry Pi Pico W based CO2 Sensor

Building a CO2 sensor using a Raspberry Pi Pico W, an SSD1306 OLED display and a CO2 Sensor.

Features

• Measure CO2, humidity and temperature using a SCD40 CO2 sensor
• Display CO2 measurements on the SSD1306 OLED display
• freeRTOS (scheduling of tasks, IPC)
• Measurements are sent to a server via tcp

Hardware

• Raspberry Pi Pico W
• Sensirion SCD40 CO2 Sensor (SCD41 should work as well, without any code changes). Make sure to power the Sensor with 5V, as I experienced issues when only powering with 3.3V!
• SSD1306 OLED display

Pins

• Pin 1 = SDA to display

• Pin 2 = SCL to display

• Pin 4 = SDA to sensor

• Pin 5 = SCL to sensor

• Pin 38 = Ground to display and sensor

• Pin 36 = 3V to display

• Sensor needs 5V external power source

Build

⚠️ I developed this project on a Mac. Some toolings will not work on other machines.

Execute the following steps to build the project:

mkdir build && cd build
EXPORT PICO_SDK_PATH=<PATH_TO_THE_PICO_SDK>
EXPORT PICO_BOARD=pico_w
EXPORT WIFI_SSID=<YOUR_SSID>
EXPORT WIFI_SSID=<YOUR_WIFI_PASSWORD>
cmake ..
make

# Optionally if you are using picotool execute this to flash the pico:
picotool load -f blink.uf2

Console Prints via minicom

To see the output of printf on the dev machine install minicom on your device brew install minicom and then execute this command:

minicom -b 115200 -o -D /dev/cu.usbmodem1101

Contribute

Feel free to contribute, open issues, ask questions or fork this project! :)