Ethernet Expansion & USB Hub: I2C Internal Pull-Up Resistors

[shawn_ricardo]

Hello,

I'd like to use J9 2W UART + I2C Port on the Ethernet Expansion & USB Hub.

Does this port include pull-up resistors? Is there a way to control resistance settings? Do you have recommendations/tutorials on how to use this specific I2C port? I have the circuitry / sensors working on bench using Arduino + RPI (I2C master). Trying to port this functionality to VOXL2 being the I2C master.

Thank you for any advice!

Shawn Ricardo

[shawn_ricardo]

Without and without ethernet expansion hub connected, ls /dev/i2c-* shows the same output:

voxl2:/$ ll /dev/i2c*
crw-rw---- 1 root i2c 89, 0 Mar  2  2023 /dev/i2c-0
crw-rw---- 1 root i2c 89, 1 Mar  2  2023 /dev/i2c-1
crw-rw---- 1 root i2c 89, 2 Mar  2  2023 /dev/i2c-2
crw-rw---- 1 root i2c 89, 3 Mar  2  2023 /dev/i2c-3
crw-rw---- 1 root i2c 89, 4 Mar  2  2023 /dev/i2c-4
crw-rw---- 1 root i2c 89, 5 Mar  2  2023 /dev/i2c-5

Appears no new i2c interfaces are detected. Is there some software that needs to be configured / enabled?

Also noticed that no SPI interfaces are newly available:

voxl2:/$  ls /dev/i2c-*
/dev/i2c-0  /dev/i2c-1  /dev/i2c-2  /dev/i2c-3  /dev/i2c-4  /dev/i2c-5

[shawn_ricardo]

For more context, I am only using SDA, SCL, and GND pins

The MCU runs on 3.3 logic level voltage -- again, was able to work properly with a RPi5 I2C

[Vinny]

Hi @shawn_ricardo
Yes, any I2C port on an expansion board has 2.2K pullups to the voltage on Pin 1 of that connector.

The Linux Kernel user guide has info on which QUPS are enabled or not in which system image.

and specifically this helps:
https://docs.modalai.com/voxl2-qups/
Note not all QUPs have actually been enabled in the system, but with the sets of ports we have enabled, we never had any customer claim of a shortage: