maemo.org - Talk - View Single Post - N900 will not allow USB OTG!

	Mara	2009-09-24 , 14:12
	Posts: 1,310 \| Thanked: 820 times \| Joined on Mar 2006 @ Irving, TX	#318

Originally Posted by allnameswereout

Nobody interested in helping BruceL? The document is http://focus.ti.com/lit/ug/sprufd4b/sprufd4b.pdf

With USB OTG on microUSB the microUSB-B is always the EH, and the microUSB-A the OTG. The Nokia N900 has a microUSB-B connector; not microUSB-AB connector. Because of this it can only function as EH; not OTG. See http://en.wikipedia.org/wiki/USB_On-...TG_Micro_Plugs and http://en.wikipedia.org/wiki/Univers...-AB_Socket_OTG (the PDF linked to earlier mentions this as well). So you would either need to hack USB on both devices, or get a microUSB-AB plug on the Nokia N900. Or do you think grounding that one pin would work? Even so, you'd then have a microUSB-B to microUSB-B link.

I read a bit of those pages, and I don't really know how to "translate" it to simple commands. It seems the USB operation status is set by setting bits in a certain register, and it should do the trick. That register is also readable which should help on debugging/troubleshooting.

Also, the presence of Vbus normally tells if the device should be Host or Peripheral. But, this signal is not a direct input to USB controller. Tranceiver chip is the one to detect it which should output its status to the OMAP. After that it is purely a SW that does the rest. This is actually good news since it tells that there is no "hard wired" control to keep the USB controller in Peripheral mode. Just writing the correct bits to this USB register should make it into Host mode.

Sorry, I don't think I can figure out how to do this exactly, but for qwerty12 this should be a piece of cake...

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