Compute Module • CM4 carrier board OTG switch for dual purpose USB port

Hi all,

I am working on a CM4 carrier board design and I have a question regarding the USB OTG implementation. As far as I understand the OTG pin controls whether or not the Pi becomes a USB device which is the functionality used to flash the emmc when the emmc boot pins are shorted.

My design will have a switch for shorting the emmc pins for flashing, but now I am wondering if I also add a switch on to the OTG port can I then use the USB port with the Pi as a host after the device is flashed and is in operation, so in short I will have two switches and two use cases:

- SW1 shorting the emmc boot pins and SW2 connecting the OTG pin to the USB port VBUS : Flashing of OS
- SW1 open and SW2 connecting my 5V to the USB port VBUS, USB port acts with Pi as host

The design be the same as the IO USB 3.0 board below but with a single throw double pole switch to alternate between OTG and 5V for the single USB port.

Raspberry Pi Compute Module 4 IO USB 3.0 Board:
https://datasheets.raspberrypi.com/cm4i ... ppnote.pdf

Then the next question if this is a sensible thing to do is if I can use a type C connector and what implications that has on the CC pins .

Cheers,
Jonas

Statistics: Posted by nasinn — Mon Feb 05, 2024 9:35 am — Replies 0 — Views 50

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