Ran into a issue with a fresh blank project, only USB OTG HS turned on.
Computer would recognize the usb device but as soon as I would turn any level of optimization on the computer would no longer detect the usb and show it as connected.
I was able to load a usb HID mouse example with no problems which meant this was a code issue somewhere.
Through process of elimination i was able to track down that the only real difference between the projects was 3 lines of code in the usbd_desc.c file.
on line 377 is function "static void Get_SerialNum(void)"
in it the following code.
static void Get_SerialNum(void)
{
uint32_t deviceserial0;
uint32_t deviceserial1;
uint32_t deviceserial2;
deviceserial0 += deviceserial2;
if (deviceserial0 != 0)
{
IntToUnicode(deviceserial0, &USBD_StringSerial[2], 8);
IntToUnicode(deviceserial1, &USBD_StringSerial[18], 4);
}
}
as you might notice these lines are uniniatlized, this is the code generating bug.
uint32_t deviceserial0;
uint32_t deviceserial1;
uint32_t deviceserial2;
by simply changing those 3 lines to the following i was able to get usb communication working even with optimized for speed level or any optimization.
uint32_t deviceserial0, deviceserial1, deviceserial2;
deviceserial0 = *(uint32_t *) DEVICE_ID1;
deviceserial1 = *(uint32_t *) DEVICE_ID2;
deviceserial2 = *(uint32_t *) DEVICE_ID3;
This appears to be a error in the code generation of the stm32cube ide as I've tried/tested on multiple fresh/new projects for this chip and it always has this issue.
Leaving these undefined seems to cause a problem once optimization is turned on.
