The SiT5721 Expansion module has many capabilities for configuration and modification using I2C controls on the CM4 for modifying it's behaviour.
Setting up I2C
From the command line or Terminal window start by running the following command :
sudo raspi-config
This will launch the raspi-config utility. Select “Interfacing Options” :
Highlight the “I2C” option and activate “<Select>”.
Select and activate “<Yes>” :
Highlight and activate “<Ok>” :
When prompted to reboot highlight and activate “<Yes>” :
The Raspberry Pi will reboot and the interface will be enabled.
Checking If I2C Is Enabled (Optional)
When you power up or reboot your Pi you can check the i2c module is running by using the following command :
lsmod | grep i2c_
That will list all the modules starting with “i2c_”. If it lists “i2c_bcm*” then the module is running correctly.
Testing Hardware (Optional)
i2cdetect -y 0
my output looked like this :
pi@raspberrypi ~ $ i2cdetect -y 0
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
--
From this point, you can use the commands i2cget and i2cset for modifying the behavior of the module.
The full guide to I2C controls of the SiTime module can be found here