USB On The Go

Thread Starter

robotDR

Joined Mar 17, 2020
21
Hi Everyone,

USB On The Go is new to me. I'm designing a board using a module that supports this and I want to take advantage of it.

So for the USB port that supports this on the module, there are these pins:

USB0_OTG_ID - "Input pin to announce OTG device insertion" (resistor value to ground according to USB spec)
USB0_VBUS_DET - "USB Port 0 Host Power Detection" (When this Port is used as a device it can be connected to a USB client port VBUS pin)

My first questions:
1) Does USB0_VBUS_DET go to pin 1 of the USB connector (VCC)?
2) If so, I can't see how it distiguinshes between 5v on the board and 5v from an external 'host'
3) USB0_OTG_ID is supposed to be connected to ground at the 'initial' host?
4) I'm confused if my device using the OTG USB port is an initial host. Seems like it could be initially a host and then switches to device if the negotiation demands it.

I have been looking at these documents:
https://www.cypress.com/file/44851/download
https://www.maximintegrated.com/en/design/technical-documents/tutorials/1/1822.html

Thank you for your time and help.
 
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