USB OTG1 in device mode without ID pin

[SCh]

Hello.

IMXRT1176DVMAA

We have one image where configured USB OTG1 port as an audio device. And USB OTG2 port as mass storage host. The audio device is not working, we tried to switch USB OTG1 to the host and successfully read USB sticks. We did a few more tests and found that the same image working on EVK-B board, but not on ours.
The most likely problem is difference in USB ID pin, it is not connected (because our USB ports only has d+ and d- (UB1112C-M7D1-4F_FOXCONN)
Is it necessary to have ID pin connected in audio mode? How we can bypass it/override OTG1?

[DanielRuvalcaba]

Hi,

Could you please confirm if you are using one USB OTG as device and the other one as host in the same MCU?

And are they running simultaneously?

Regards,

Daniel.

[SCh]

Thank you for answer, Daniel.

Yes, confirm.
USB OTG1 - is audio device.
USB OTG2 - is Mass Storage Host.
Both are running in CM7 and working at the same time.

On EVK we have recorded sound from USB OTG1 'Speaker' to file on USB Key in USB OTG2.

On EVK-B however we have never tried that, but I can confirm that USB OTG1 'Speaker' and 'Microphone' were recognizable by my PC on WIN11, and MCU could VID/PID and first directory of plugged in USB key.

On our custom board (with references from EVK-B but without ID pins that i mentioned before) we could get only host mode working (Mass Storage Host class). Successfully read keys. We also tried to move audio to OTG2 and still no luck there.

Regards,
Serhii.

[DanielRuvalcaba]

If the SW is running correctly in the EVK, seems the problem is on the hardware side of your board.

By any chance, are you able to share your schematic, or at least the way you connected the USB in your design?

Regards,

Daniel.

[SCh]

Hi, thanks for reply.

Attached usb part design. Our idea that no ID pin is somehow triggering OTG functionality in MCU. But I have no idea how to bypass that (if it possible)

About design:
USBTRI - part of 3 usb connectors
AU9 - USB HUB. Where DM/P 1..4 is 4 in-ports. And DMU/DPU is out-port.
AU54 - signals switch. We control USB_EN pin, and in default state connections is green.
AP1 - type-c connector

So, in default state PC seeing all usb keys that connected to USBTRI connectors. But not audio-device that was enumerated on OTG1.

I'm now trying to register mass storage device and connect it to PC, will report later if it will work before your answer

[SCh · Accepted solution]

We found an issue in our design. There is VBUS on OTG1 that should be powered from some external source, and we havent connected it to anything. And our host mod was working with triple-usb-ports because they were powered from otg2 source.