Building a custom CO₂ sensor has become a popular hobby project in the last weeks due to the COVID-19 pandemic. For that reason I ordered multiple Sensirion SCD30 CO₂ sensors. Sensirion claims an accuracy of ± (30 ppm + 3% MV) at 25 °C and the sensor supports an Automatic Self-Calibration (ASC) (see section 1.4.6 of datasheet).
As I noticed quite some difference between measurements of different sensors, I was curious about the accuracy and self-calibration. Therefore I build a custom PCB, which hosts eight sensors in vicinity, a Bosch BMP280 pressure sensor for pressure calibration, a I2C multiplexer and an ESP32 for low-level communication with the sensors. Continue reading