Is it possible to get Vbus disconnect notification on self-powered USB HS device in STM32H743 without wiring VBus to an IEXT port?

Greg Smith · ‎2018-10-04

I have a working USB2 (ULPI) device mode interface, and want to detect cable removal. There appears to be provision for this: OTG_GINTSTS has SRQINT and OTGINT bits and OTG_GOTGINT has the OTGINT bit, but I do not seem to get any response to cable removal, though the VBus signal does indeed drop to 0V when the cable is removed.

I can detect this signal using other methods, but it seems odd that all the registers and documentation suggest that this should work, and the STM provided HAL and LL code is there to do it... The documentation does not suggest that this is a Host only feature. Am I missing something?

waclawek.jan · ‎2018-10-04

I don't get it: where do you have connected VBUS from the USB connector? Any schematics?

JW

Greg Smith · ‎2018-10-07

Look at the schematic for the STM32H&43 EVAL board if you want to see how things are wired for the HS connection. The USB works OK, but there is no status bit set to indicate that the VBUS input has gone low, indicating end of session. It is possible to connect the VBUS (via an opto-isolator to avaod problems) to a spare GPIO and use this as an interrupt line, but it feels odd that you should need to do this as the hardware has all the status bits to detect this.

waclawek.jan · ‎2018-10-08

Ah, so you have VBUS connected to the ULPI PHY?

Sorry I don't have experience with ULPI connected USB.

JW