STM32F302 use USB double buffer, the transmit data will over buffer setting

[Felix1]

Hi All

Hardware: STM32F302

Software: STM32Cube_FW_F3_V1.10.0

As below is USB descriptor

/* USB Speaker Audio Streaming Descriptor */

 0x07,         /*bLength: Endpoint Descriptor size*/

 USB_DESC_TYPE_ENDPOINT, /*bDescriptorType:*/

 AUDIO_OUT_EP1, /*bEndpointAddress: Endpoint Address (IN)*/

 USBD_EP_TYPE_ISOC,         /*bmAttributes: */

 0xe0, /*wMaxPacketSize: 2 Byte max */

 0x00,

 0x01,         /*bInterval: */

 /* 07 byte*/

      /* USB Mic Audio Streaming Descriptor */

 0x07,         /*bLength: Endpoint Descriptor size*/

 USB_DESC_TYPE_ENDPOINT, /*bDescriptorType:*/

 AUDIO_IN_EP1,

 USBD_EP_TYPE_ISOC,         /*bmAttributes: */

 0x80, /*wMaxPacketSiz */

 0x00,

 0x01,         /*bInterval:)*/

 /* 07 byte*/

and double buffer setting

HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , AUDIO_OUT_EP1 , PCD_DBL_BUF, 0x01F80118);

 HAL_PCDEx_PMAConfig((PCD_HandleTypeDef*)pdev->pData , AUDIO_IN_EP1 , PCD_DBL_BUF, 0x031802D8);

When use API USBD_LL_Transmit (pdev,AUDIO_IN_EP1,(uint8_t*)(mic_buffer),0x36);

to transmit data, the data will over my buffer setting, the transmit data around 400 bytes.

How to fixed this problem?

Thanks.​

[Ben K]

The USB peripheral's HAL driver (PCD) has a known limitation: it directly maps EPnR register numbers with endpoint addresses. This works if all OUT and IN endpoints with the same number (e.g. 0x01 and 0x81) are the same type, and not double buffered. However, isochronous endpoints have to be double buffered, therefore you have to use an endpoint number that's unused in the other direction. E.g. in your case, set AUDIO_OUT_EP1 to 0x01, and AUDIO_IN_EP1 to 0x82. (Or you can drop this USB stack altogether as I did.)

[alfichua]

Hi,

I had a similar issue and had used a different endpoint value for the audio out (0x05) and audio in(0x86).

Could you provide some advise on how to proceed without using the USB stack? If there is any sample, it would be better =)

Thanks.

[Ben K]

I made this library: https://github.com/IntergatedCircuits/USBDevice

https://github.com/IntergatedCircuits/USBDevice4Cube

This lets you use any valid endpoint numbers. However there's no support for Audio class atm.

[Kamil Kisiel]

Thanks for your insight on this Ben, I was bashing my head against the same problem for quite a while and couldn't quite figure it out. Using different endpoint numbers has thankfully solved it for me.