How Many I2C Devices Can be Connected to USB-845X?

Updated May 5, 2020

Reported In

Hardware

  • USB-8451
  • USB-8452

Issue Details

  • What is the maximum number of I2C devices can be connected to USB-845X?
  • USB-845X has 7-bits I2C address. Does it means it can support up to 128 devices?

Solution

Up to eight devices can be connected to I2C bus of USB-845X. Despite having 7-bits I2C address, the upper four bits are fixed and assigned to specific categories of devices (for example, 1010 is assigned to serial EEPROMs). Only three lower bits are used as hardware address pins.