Showing results for 
Search instead for 
Did you mean: 

USB HID issue with H743 @ 480 MHz

Peter Mather
Associate III

I'm running a USB keyboard on an H743. This works completely reliably at all CPU speeds up to and including 400MHz. However, above 400 MHz the connection is no longer reliable. Sometimes the keyboard connects perfectly and then it will work properly as expected with no issues. including re-connecting if unplugged and re-plugged. Sometimes repeated resets are needed before a connection works. In this case unplugging and re-plugging will have no affect.

I suspect some sort of race condition in the USB initialisation that only manifests itself when the CPU speed is very high but whatever is happening is deep inside the USB code.

Has anyone got HID working reliably at 480MHz?

I'm running on a Nucleo-H743ZI2.

Note: the USB power drive pin is PD10 on this board rather than PG6 on the original Nucleo-H743 and also the sense of the power drive is reversed compared to the original board.