Troublesome chips:

Some sensors or chips have non-standard behavior that causes issues when trying to use I2C. Here's a few of the ones to watch for

  • AGS20MA - Use a bus speed of 20-30 kHz.
  • ATECCx08 - Use slow-speed I2C to get out of sleep mode.
  • BNO055 - Uses clock stretching, and sometimes needs to be reset.
  • CCS811 - Uses clock stretching.
  • LC709203F - Repeated start, clock stretching, sleep mode
  • MCP9600 (date codes 1845 or before) - bug: duplicate data from register. reads, perhaps due to clock stretching.
  • MCP9600, MCP9601 - Repeated start, clock stretching. Often will not respond to zero-length writes, so scanning the I2C bus to find the device can fail.
  • PN532 - Clock stretching.

If you're using Raspberry Pi with these chips, check out our guide on how to work-around clock stretching.

Troublesome microcontrollers:

  • MicroChip Atmel SAMD21, SAMx5x - I2C bus frequency below 95 kHz not available when I2Cperipheral is drive with a 48 MHz clock, which is typical. CircuitPython checks for out-of-range bus frequencies.

This guide was first published on Jul 29, 2017. It was last updated on Jul 29, 2017.

This page (Troublesome Chips) was last updated on Aug 13, 2022.

Text editor powered by tinymce.