Project forked to explore how to use this board.

main.cpp : With I2C communication, each slave on the bus has its own address, a hexadecimal number that allows the ESP32 to communicate with each device.
This code will scan the I2C BUS and return your devices’ I2C address.

For ARDUINO IDE: You can copy/paste the code from main.cpp Don't forget to install libraries.

• M5Stamp C3U can use any GPIO as I2C BUS. You need to define the pin you want to use with Wire.begin(I2C_SDA, I2C_SCL);
  I have tested on (1,0) and (6,7) _(sda, sdc)
• But only have 1 BUS I2C. (ESP32 can manage 2 BUS I2C)
  Check this doc: Multiple I2C devices (same bus, different addresses)

For more I2C stuff, check issue #2