No data-role swap recognized with X Cube TCPP

[chris_O]

Hello,

I am using a STM32G0B1xx MCU with the X-CUBE-TCPP v4.1.0 stack an FreeRTOS. I am trying to setup a USB-c port with OTG-functionality. I am having some problems understanding your X-CUBE-TCPP-stack.

Some background info:

I am initializing the software with MX_UCPD1_Init() and MX_USBPD_Init() provided by the original stack/CubeMX. I am testing the connection with several USB-devices an -hosts.  We tested a previous version of our software on a  NUCLEO-G071RB in combination with a X-NUCLEO-DRP1M1 with your Tool "STM32CubeMonitor-UCPD", which was working fine.

1. The DPM_Params[0].PE_DataRole is always defined as USBPD_PORTDATAROLE_UFP, no matter what i connect to the USB-c port. Is this intended?

2. I do not get a Notification for USBPD_NOTIFY_DATAROLESWAP_UFP or for USBPD_NOTIFY_DATAROLESWAP_DFP in here, no matter what I connect to the USB-c port:

/**
  * @brief  Callback function called by PE to inform DPM about PE event.
  * @PAram  PortNum The current port number
  * @PAram  EventVal @ref USBPD_NotifyEventValue_TypeDef
  * @retval None
  */
void USBPD_DPM_Notification(uint8_t PortNum, USBPD_NotifyEventValue_TypeDef EventVal)
{
/* USER CODE BEGIN USBPD_DPM_Notification */
  /* Manage event notified by the stack? */
  switch(EventVal)
  {
//...
    case USBPD_NOTIFY_DATAROLESWAP_UFP:
    	HAL_NVIC_SetPendingIRQ(EXTI2_3_IRQn); // this will set EVENT_DATAROLE_CHANGE
    	break;
    case USBPD_NOTIFY_DATAROLESWAP_DFP:
    	HAL_NVIC_SetPendingIRQ(EXTI2_3_IRQn); // this will set EVENT_DATAROLE_CHANGE
    	break;
    default:
      DPM_USER_DEBUG_TRACE(PortNum, "ADVICE: USBPD_DPM_Notification:%d", EventVal);
      break;
  }
/* USER CODE END USBPD_DPM_Notification */
}

I just get  two notification in the beginning, both USBPD_NOTIFY_USBSTACK_START.

Do you have any hints for me where to start?

[FBL · Accepted solution]

Hi @chris_O 

USBPD and USB stack run in parallel. If we see that the data role swap is done in the USBPD trace (UCPD monitor) it doesn't mean that the USB stack is in the right state. Here is the default the USB role when attached.

To be sure that the USB stack role is aligned with USBPD status, See the wiki.

A notification system is in place for USBPD stack to notify USB part :

void USBPD_DPM_Notification(uint8_t PortNum, USBPD_NotifyEventValue_TypeDef EventVal)
{
  switch(EventVal)
  {
    case USBPD_NOTIFY_USBSTACK_START:
    {
	if (USBPD_PORTDATAROLE_DFP == DPM_Params[PortNum].PE_DataRole)
	{
	  USBPD_USBIF_HostStart(PortNum);
	}
	else
	{
	  USBPD_USBIF_DeviceStart(PortNum);
	}
	break;
    }
    case USBPD_NOTIFY_USBSTACK_STOP:
    {
	 if (USBPD_PORTDATAROLE_DFP == DPM_Params[PortNum].PE_DataRole)
	 {
	  USBPD_USBIF_HostStop(PortNum);
	 }
	 else
	 {
	  USBPD_USBIF_DeviceStop(PortNum);
	 }
	 break;
  }
   case USBPD_NOTIFY_DATAROLESWAP_DFP :
   {
    USBPD_USBIF_Swap2Host(PortNum);
    break;
   }
  case USBPD_NOTIFY_DATAROLESWAP_UFP :
  {
    USBPD_USBIF_Swap2Device(PortNum);
    break;
  }
}

1.  

[chris_O]

Hello, 

thanks for the reply, I have a better understanding now of the stack. I configured our port in the USBPD-stack as sink-only (it should also stay so), so it makes sense I get per default a UFP-port. 

For OTG-functionality, i need to detect if my opponent wants to act as device or host, is this even possible with your stack?
Is it possible with the contents of  DPM_Params after the event USBPD_NOTIFY_USBSTACK_START to detect if a host is detected? Because I do not get the event USBPD_NOTIFY_DATAROLESWAP_DFP after connecting to a host like a Laptop.

Thanks for your help and best regards 
Christian

[FBL]

Hi @chris_O 

Next step could be to put a breakpoint of a trace to check if the right USB (host or device) stack has started to make sure it has started effectively. Don't rely on the trace like 'USB device stack started', it could be fake like a remaining old debug message.

So the best way to check is to put a breakpoint in the code you mentioned (between USBPD calling USB) and see what happens to check if the USB stacks are really started.

[chris_O]

Hello,

the USB-stacks are starting fine. Manually switching between device and host-mode is also working.

Did I get this right: the stack with STM32G0 does not support automatically switching between USB-dataroles (OTG)?

Best regards 
Christian

[FBL]

Hi @chris_O 

Sorry for my late reply! Indeed this is possible using USB PD stack.