USB_DEVICE_HID_ReportReceive Function

This function submits the buffer to HID function driver library to receive a report from host to device. On completion of the transfer the library generates USB_DEVICE_HID_EVENT_REPORT_RECEIVED event to the application. A handle to the request is passed in the transferHandle parameter. The transfer handle expires when event handler for the USB_DEVICE_HID_EVENT_REPORT_RECEIVED exits. If the receive request could not be accepted, the function returns an error code and transferHandle will contain the value USB_DEVICE_HID_TRANSFER_HANDLE_INVALID.

USB_DEVICE_HID_RESULT USB_DEVICE_HID_ReportReceive(
    USB_DEVICE_HID_INDEX instanceIndex, 
    USB_DEVICE_HID_TRANSFER_HANDLE * handle, 
    void * buffer, 
    size_t size
);

Preconditions

USB device layer must be initialized.

Parameters

Parameters	Description
instanceIndex	HID instance index.
transferHandle	HID transfer handle.
buffer	Pointer to buffer where the received report has to be received stored.
size	Buffer size.

Returns

USB_DEVICE_HID_RESULT_OK - The receive request was successful. transferHandle contains a valid transfer handle.

USB_DEVICE_HID_RESULT_ERROR_TRANSFER_QUEUE_FULL - internal request queue is full. The receive request could not be added.

USB_DEVICE_HID_RESULT_ERROR_INSTANCE_NOT_CONFIGURED - The specified instance is not configured yet.

USB_DEVICE_HID_RESULT_ERROR_INSTANCE_INVALID - The specified instance was not provisioned in the application and is invalid.

Remarks

While the using the HID Function Driver with the PIC32MZ USB module, the report data buffer provided to the USB_DEVICE_HID_ReportReceive function should be placed in coherent memory and aligned at a 16 byte boundary. This can be done by declaring the buffer using the __attribute__((coherent, aligned(16))) attribute. An example is shown here

uint8_t data[256] __attribute__((coherent, aligned(16)));

Example

  USB_DEVICE_HID_TRANSFER_HANDLE hidTransferHandle;
  USB_DEVICE_HID_RESULT result;

  // Register APP_HIDEventHandler function
  USB_DEVICE_HID_EventHandlerSet( USB_DEVICE_HID_INDEX_0 ,
                                  APP_HIDEventHandler );

  // Prepare report and request HID to send the report.
  result = USB_DEVICE_HID_ReportReceive( USB_DEVICE_HID_INDEX_0,
                             &hidTransferHandle ,
                             &appReport[0], sizeof(appReport));

  if( result != USB_DEVICE_HID_RESULT_OK)
  {
     //Handle error.

  }

  //Implementation of APP_HIDEventHandler

  USB_DEVICE_HIDE_EVENT_RESPONSE APP_HIDEventHandler
  {
    USB_DEVICE_HID_INDEX instanceIndex,
    USB_DEVICE_HID_EVENT event,
    void * pData,
    uintptr_t context
  }
  {
      USB_DEVICE_HID_EVENT_DATA_REPORT_RECEIVED reportReceivedEventData;
      // Handle HID events here.
      switch (event)
      {
          case USB_DEVICE_HID_EVENT_REPORT_RECEIVED:
             if( (reportReceivedEventData->reportSize == sizeof(appReport)
                  && reportReceivedEventData->report == &appReport[0])
             {
                // Previous transfer was complete.
             }
             break;
          ....
      }
  }

USB Libraries Help > USB Device Libraries > USB HID Device Library > Library Interface > a) Functions > USB_DEVICE_HID_ReportReceive Function

MPLAB Harmony USB Stack

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