I2C Sniffer Build - StephenDone/kickr_shifters GitHub Wiki

An I2C sniffer is really useful to see what data is actually going across the bus and gain an understanding of how I2C works. This helped me get my I2C calls just right in my python test script.

To build the sniffer, you need a RP2040 board, some heat shrink and half a Stemma QT cable.

I used a Waveshare RP2040-one

You then need the software from https://github.com/jjsch-dev/pico_i2c_sniffer

The IO pins you need to connect the Stemma QT cable to are detailed at https://github.com/jjsch-dev/pico_i2c_sniffer?tab=readme-ov-file#connection-diagram.

The signals need to be matched to the Stemma QT pinout

Pico 2040 Signal	Stemma QT Wire Colour	I2C Signal
3.3V	Red	3.3V
GP3	Yellow	Clock - SCL
GP0	Blue	Data - SDA
0V	Black	0V

Details of how to flash the firmware onto the Pico are at https://github.com/jjsch-dev/pico_i2c_sniffer?tab=readme-ov-file#download-the-firmware-in-raspberry-pi-pico

I should have taken a picture of the board before adding the heatshrink - sorry.