This is the PCB only. The Raspberry Pi Pico, sensor, etc are not included.

This is a Raspberry Pi Pico based CO₂ sensor, compatible with the Sensirion SCD30, a high-quality Nondispersive Infrared (NDIR) based CO₂ sensor capable of detecting levels of CO₂ from 400 to 10000ppm. An OLED screen shows the detailed ppm measurement, as well as the ambient temperature and the uptime of the device.

With the current COVID-19 pandemic, there is a lot of discussions around the adequate level of ventilation in the home, workplaces, and especially schools. CO₂ levels increase as we breathe out in enclosed spaces, and is a useful proxy for the potential level of virus aerosols in the air.

The CO₂ sensor also includes an RGB LED for easily reading the current CO₂ levels. Red for readings greater than 800ppm, blue for levels between 600ppm and 800ppm, and green for levels below 600ppm.

The PCB also includes solder points for the much cheaper CCS811 sensor that can measure equivalent CO₂, however, this has not been tested and is not implemented in the current software. In addition, the accuracy of the CCS811 can be improved with reading from a separate temperature sensor, but connections for this are not on the 1.0 board. If there is sufficient demand, version 1.1 will include full support for the CCS811 and the additional temperature sensor.

Note - the footprint of the Raspberry Pi Pico makes insertion into PCB holes difficult if the header pins have already been attached to the Pico. I recommend inserting the header pins into the sensor PCB first, then placing the Pico on the pins, and then soldering the pins to the Pico.

You will need to program the Raspberry Pi Pico to complete this project, so some knowledge of that is required. Source code for the Sensor application is provided.

Bill Of Materials

https://gist.github.com/rubikcuber/d9d7eb6201366d5dfacb228a5be3095f

Pico Code

https://gist.github.com/rubikcuber/61d2c6f0a04420fec4aca5a2160f2126