USB host with USB ID pin unconnected

David Kronstein1

I mistakenly left the USB ID pin floating on a custom DM8148 board. Can the USB port still be used in host mode? USB_DRVVBUS is never driven high.

There's a kernel config option for software or hardware USB ID source (forget exactly what it was called), but neither option seems to allow the USB port to work (USB_DRVVBUS is never driven high to enable power to the port).

over 12 years ago

0 Vladimir-XID over 12 years ago

TI__Genius 11470 points

Hello David,

Please, check this thread:

DM814X OTG USB ID Pin

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/235267.aspx

Let me know if something more is required. Thank you.

Vladimir

0 David Kronstein1 over 12 years ago in reply to Vladimir-XID

Prodigy 90 points

Hi Vladimir,

I'm not quite clear what to do. Do I need to modify the USB driver too add a write to USB0MODE? If so, which file?

Also, in the TRM it mentions "if USB0MODE=0, the state of the USB_ID pin controls the role the controller assumes.", however I would be setting the register to 0 (IDDIG = 0) to use USB A mode. Could you clarify this? Does a write to this register latch something?

David

0 Vladimir-XID over 12 years ago in reply to David Kronstein1

TI__Genius 11470 points

Hi David,

I don't know; maybe the TRM text could mean that: On devices like DM814x (that have USB ID pin) the forced host mode cannot be controlled by software/registers.

If "iddig" register field of USB0MODE is 1, controller is forced to B type device - peripheral.

If "iddig" register field of USB0MODE is 0, the role it is controlled by the USB ID pin, so in that case to force host mode, you have to connect the the USB ID pin to GND (optionally with a jumper).

Maybe there could be more specifics; it could be something else.

Thank you.

Vladimir

0 Guilherme Haas over 12 years ago in reply to Vladimir-XID

Intellectual 345 points

I did the same mistake. I left my ID pin floating to work as host.

If anyone fix it by software let me known.

0 Vladimir-XID over 12 years ago in reply to Guilherme Haas

TI__Genius 11470 points

Hi Guilherme,

My previous post exactly contains my concerns for a software fix. The above seems internal for the USB controller and thus it cannot be workarounded by software. I don't know. You can refer to the TRM.

Thank you.

Vladimir

0 David Kronstein1 over 12 years ago in reply to Guilherme Haas

Prodigy 90 points

I tried to force host mode by using an undocumented bit in one of the control registers that apparently would control host/device mode in order silicon revisions, but this does not work in the later revision that I'm using. It looks like a board spin is required if no jumper can be installed to hold the ID pin low.

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USB host with USB ID pin unconnected

DM814X OTG USB ID Pin