Multi I2C Hat for Raspberry Pi and Acme Sensor boards

This article explains how to use the Multi I2C multiplex HAT for Raspberry Pi designed to connect up to 8 Acme Sensors

Create a Raspbian OS microSD with the latest lite version:

Insert this line inside the /boot/config.txt file.

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on
dtoverlay=i2c-mux,pca9548=1

Is not requested to enable the I2C using raspi-config

Install the i2c-tools to check the I2C bus from user space.

$ sudo apt update
$ sudo apt -y install i2c-tools

Check the i2c devices available by typing:

$ i2cdetect -l

i2c-1   i2c         bcm2835 (i2c@7e804000)              I2C adapter
i2c-20  i2c         fef04500.i2c                        I2C adapter
i2c-21  i2c         fef09500.i2c                        I2C adapter
i2c-22  i2c         i2c-1-mux (chan_id 0)               I2C adapter
i2c-23  i2c         i2c-1-mux (chan_id 1)               I2C adapter
i2c-24  i2c         i2c-1-mux (chan_id 2)               I2C adapter
i2c-25  i2c         i2c-1-mux (chan_id 3)               I2C adapter
i2c-26  i2c         i2c-1-mux (chan_id 4)               I2C adapter
i2c-27  i2c         i2c-1-mux (chan_id 5)               I2C adapter
i2c-28  i2c         i2c-1-mux (chan_id 6)               I2C adapter
i2c-29  i2c         i2c-1-mux (chan_id 7)               I2C adapter

Insert an Acme Sensor on I2C-22 connector and type:

$ i2cdetect -y 22

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --
  • UU ad address 0x70 is the address of TCA9548A mux used by the i2c-mux driver so non available to be managed by user space
  • 44 ad address 0x44 is the address of the Acme Sensor plugged on I2C-22 Acme Sensor connector

Schematic

Links