BeagleY-AI J15 CSI0 Pin 18 details

General Discussion
1

Hi,

I need help with controlling Pin 18 (RPi_NC) on CSI0(J15) connector.

My requirement: I need to toggle or set Pin 18 HIGH to provide power to my external board. Only after this pin is set HIGH can I communicate with my board over I2C. Currently, this pin appears to be marked as “RPi_NC” (not connected) in the schematic.

My question:
Is there a way to control this pin through device tree configuration, driver implementation, using devmem, or any other alternatives to use it as a GPIO output? I need to be able to set it HIGH before initiating communication with my board.

Any guidance on how to configure and control this pin would be really helpful.

Thanks in advance!

2

My answer:

Do a search for gpio hog and you’ll be much wiser very soon.

3

I noticed Pin 18 on J15 (CSI0) is marked as “RPi_NC” in the schematic. If it’s truly not connected to any GPIO on the SOM, then GPIO hogging won’t work since there’s no GPIO to control. Or will it work even if it is “NC” ?

Can you confirm if Pin 18 is actually routed to a GPIO internally despite the NC marking? Or is there documentation showing the actual pin mapping?

J15_CSI0
J15_CSI0959×628 68.2 KB

Thanks.

4

Without checking, could this pin be N/C on the Pi side I wonder…

With regards to the documentation, you’re looking right at it.
MCU_GPIO0_16 through the 0Ω resistor R245.

5

The “RPi_NC” label on the CSI0 pin 18 side initially confused us, so we weren’t sure if it was actually usable. Thanks for pointing out the MCU_GPIO0_16 connection through R245 and confirming that the pin is in fact wired and controllable.

Thanks