AM5728: Confirm the GPIO pin assignment for USB

Kaka

Other Parts Discussed in Thread: AM5728

Hi TI Experts,

Please let me confirm the following question.
[Question]
According to the TRM on page 5959, there are some use case for USB functions. And especially this device can support the DRD function. So, if customer would like to use this, they need to assign the GPIO for ID pin. Can customer choose any GPIOs for this?

I also checked the schematic check list for AM572x, but I could not find this.

Best regards.

Kaka

over 9 years ago

0 Wolfram Stumpf over 9 years ago

Intellectual 445 points

Hello Kaka,

I had basically the same question in :

e2e.ti.com/.../468334

USB ID can be a GPIO of your choice.

Regards

Wolfram Stumpf

0 Kaka over 9 years ago in reply to Wolfram Stumpf

Guru 24520 points

Hi Wolfram,

Thank you for your comments.
I will inform this to my customer.

Best regards.
Kaka

0 Kaka over 9 years ago in reply to Kaka

Guru 24520 points

Hi Wolfram,

By the way, I have a question for this.
How should customer configure a GPIO which they choose as ID pin?

Will they need to prepare the software for DRD function?

Best regards.
Kaka

0 Wolfram Stumpf over 9 years ago in reply to Kaka

Intellectual 445 points

Hello Kaka,

the DRD stuff is (more or less) completely SW. Therefore, the USB_ID is a "normal" GPIO with an external Pull-Up:

- a connected slave would pull it to GND to request SW in AM5728 to act as a host
- a connected host would leave the pin and AM5728 would read a logic high due to the pull an SW knows to act as a slave.

I can't give you more hints in regard to SW. I will use Uboot/Linux for the basic board bring-up and forward the board to the SW guys.

For Linux, you can configure the ID pin via DTS.

Regards

Wolfram

0 Kaka over 9 years ago in reply to Wolfram Stumpf

Guru 24520 points

Hi Wolfram,

Thank you for your response.
I could understand them.

Best regards.
Kaka

0 -DK- over 9 years ago in reply to Kaka

TI__Mastermind 27890 points

Please ensure that the pullup for the USB_ID is sourced from the same power rail that supplies the GPIO you choose for this functionality. This will prevent cross-domain leakage inside the SoC.

The TRM makes note of this in the relevant USB diagrams but I wanted to make sure you didn't miss it.

0 Kaka over 9 years ago in reply to -DK-

Guru 24520 points

Hi DK,

Thank you for your advice. I alert my customer to handle this with care.

Best regards.
kaka

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AM5728: Confirm the GPIO pin assignment for USB