32h743 does not work under certain circumstances

[EdoFranzi]

Hi,
I am facing a strange behavior . I set TinyUSB to work with a CDC & MSC devices (like the proposed example in the package).
Now, I ported the example cdc_msc in my environment (RTOS on a Nucleo stm32743). Here I have a strange behavior . If tud_task(); is placed in a loop (using 100% of the cpu) the program works (I can communicate via the cdc and I can see the mounted disk on my desktop).
This works (but it uses 100% of the cpu)

        ...
        tud_init(BOARD_TUD_RHPORT);
	while (TRUE) {

// TinyUSB device task
		tud_task();
	}
        ...

This does not work ...

        ...
        tud_init(BOARD_TUD_RHPORT);
	while (TRUE) {

// Waiting for 500us (tud_task(); is called ~ every 500us)
                kern_suspedProcess(500);

// TinyUSB device task
		tud_task();
	}
        ...

Of course, the second example should be the good one; kern_suspedProcess(500) suspend the process for 500us and change the context. With the scope I measured that tud_task(); is really called regularly @ 500us with a very little jitter .
Exactly the same code works perfectly on the Nucleo stm32l4r5.
Any ideas about this strange behavior ?
BR
Edo

[hathach]

which RTOS you are running ?

[EdoFranzi]

Hi, it is a professional non open source RTOS.
Btw, I have just did a simple test on your cdc_msc example (so no RTOS).
Your loop works well as long as I use 100% of the cpu ...
This is your main:

/*------------- MAIN -------------*/
int main(void)
{
  board_init();

  // init device stack on configured roothub port
  tud_init(BOARD_TUD_RHPORT);

  while (1)
  {
    tud_task(); // tinyusb device task
    led_blinking_task();

    cdc_task();
  }

  return 0;
}

Now, I have just added an WFI to be stopped until I receive an interruption (usb or 1ms SysTick). Now, something goes wrong with the tinyUSB.

/*------------- MAIN -------------*/
int main(void)
{
  board_init();

  // init device stack on configured roothub port
  tud_init(BOARD_TUD_RHPORT);

  while (1)
  {
__asm("wfi\n");

    tud_task(); // tinyusb device task
    led_blinking_task();

    cdc_task();
  }

  return 0;
}
 

Any idea? I tried other stm (not H7) and things work well
BR
Edo

[hathach]

If you are looking for exact code, try to find my PR to circuitpython regarding the low power feature for nrf52 or samd as mentioned above. Since I don't really remember everything.

[EdoFranzi]

hathach, thank you for your reply. The problem is not the generic low power features. The problem is the low power feature for the stm32H743. I tried many other architectures and all work fine. What I suspect is that there is a problem with the stm32H743 implementation. This is why I came back to your original and very simple example ... that does not work.

[hathach]

I don't know why it works for other cortex and not with stm32h743. It can be a specific setting of the MCU. For that you should try to go through h7 manual/datasheet to troubleshoot the issue. My knowledge is pretty much limitted to usb and related work.

[BitLoose]

Did you solve the problem? There are posts on the STM Community about the WFI sleep functions not working as per the manual, not sure if a latency issue might affect your code.
I'm also looking for a dual role USB driver for the STM32H743 as STM have only very crude drivers that won't even managed a mouse and keyboard at the same time, sigh

[EdoFranzi]

Hi BitLoose,
I found the problem time ago (I discovered the solution in a ST blog discussion).
In the usb initialisation it is mandatory to add this instruction:

RCC->AHB1LPENR &= ~RCC_AHB1LPENR_USB2OTGHSULPILPEN;

This was communicated to Hathach for updating the package.
Now the H743 (and other H7) works perfectly.