USB PD enable display port [STM32N6 - SNK]

[Brenden_PLUS]

* board - STM32N6570-DK

*  using STM Cube 1.19.0

* Example - USBPD_SNK

 

Goal - to enable Display port

 

Problem - is i'm getting stuck with the current example.  It gets stuck at SVDM_deiscovery_identity part.  Which in that packet i should be able to start to tell the host that i have display port capability, but i what is currently set it that the message is unsupported.  How would i go about enabling this.

 

Thoughts - In usbpd_vdm_user.c it seems like it has all the stuff that i need to start sending back these kind of messages but they don't seem to be called anywhere.  

There's a function called

* USBPD_VDM_DiscoverSVIDs()

But it doesn't seem to be called.  

 

 

Capture from a STM32 PD G0 - with STM32CubeMonitor app

[Brenden_PLUS]

In usbpd_dpm_conf.h it seems you can edit the DPM_Settings.

 

So i enabled 

.PE_VDMSupport = USBPD_TRUE,

.PE_RespondsToDiscovSOP = USBPD_TRUE, /*!< Can respond successfully to a Discover Identity */ .PE_AttemptsDiscovSOP = USBPD_TRUE,

 

None of these made any further changes.  

[FBL]

Hi @Brenden_PLUS 

It seems we are getting strange behavior running the example ! An internal ticket is submitted to dedicated team (221407) for further investigation. 

About USBPD_VDM_DiscoverSVIDs API is called to retrieve SVID supported by device and answer to SVDM Discovery SVID init message sent by port partner

[Brenden_PLUS]

Do you have any info on whats weird about it?  I've currently moved to a different task, but figuring out this PD is very important to the project.  Just want to make sure this problems is or is not impeding my progress on my task. 

[FBL]

Hi @Brenden_PLUS 

I assume this line, __HAL_PWR_GET_FLAG(PWR_FLAG_USB33RDY) returns true if PWR_FLAG_USB33RDY is set. So, if the flag is set, the code is stuck in the instruction while(__HAL_PWR_GET_FLAG(PWR_FLAG_USB33RDY));

If the code is waiting for the flag to be set, a simple correction could be

 while(!__HAL_PWR_GET_FLAG(PWR_FLAG_USB33RDY));

Keep me updated, if you have further questions.

[Brenden_PLUS]

Currently using a

* STM32G071 nucleo board

 

SUB problem

The larger sub problem was i couldn't figure out how to get the VDM messages to work.

 

Solution

• use reference example DEMOUCPD with cpu STM32G081 eval board
• make sure your using USBPDCORE_PD3_FULL 
  • This is a compile part of the library that's linked in the middleware layer
• Enable VDMSupport
  • You can do this in the ioc file in the middleware 
  • Or usbpd_dpm_conf.h
• In usbpd_dpm_userr.c, you need to init USBPD_VDM

USBPD_StatusTypeDef USBPD_DPM_UserInit(void)
{
/* USER CODE BEGIN USBPD_DPM_UserInit */
USBPD_VDM_UserInit(USBPD_PORT_0);
 return USBPD_OK;
/* USER CODE END USBPD_DPM_UserInit */
}​

 

•  in usbpd_vdm_user.c you need to actually setup the callbacks for this subsystem 

USBPD_StatusTypeDef USBPD_VDM_UserInit(uint8_t PortNum)
{
/* USER CODE BEGIN USBPD_VDM_UserInit */

 USBPD_PE_InitVDM_Callback(PortNum, (USBPD_VDM_Callbacks *)&vdmCallbacks);

 return USBPD_OK;
/* USER CODE END USBPD_VDM_UserInit */
}

 

At this point you'll need to start defining some of these objects and looking at the eval example will help a lot with it.  At this point mixing most of the code in the usbpd_vdm_user.c from the eval project my usb monitor program looks like this.  Which was huge!  You can see the SNK send back a SVDM discovery identity packet!

 

Documentation that was really helpful

• STM32 PD guide
• Software stack guide

From the software stack guide

 

[FBL]

Hi @Brenden_PLUS 

Welcome and thank you for your feedback.

I suggest to nominate this thread as frequently asked question !