TINYUSB UAC2 device issue: data transfer is out of sync??

[sidharth-458]

I

am working on USB audio class 2.0. I am using STM32F401, where I have connected SD card using SPI protocol and at the other end I have connected mobile using USB ( USB Audio Class 2.0). I have used tinyusb for USB support and FatFS for Filesystem.

AIM:

1. I have to read the PCM samples from SD card.

2. Concurrently I need to send PCM samples to over USB ( USB Audio Class 2.0) to HOST (mobile).

3. I am recording the PCM samples into my mobile phone recorder.

point 1 and 2 is achieved, but issue in occurring in point 3. The recorded file is noisy

I have using configuration which mention below:

tusb_desc_device_t const desc_device =

{

.bLength = sizeof(tusb_desc_device_t),

.bDescriptorType = TUSB_DESC_DEVICE,

.bcdUSB = 0x0200,

// Use Interface Association Descriptor (IAD) for Audio

// As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1)

.bDeviceClass = TUSB_CLASS_MISC,

.bDeviceSubClass = MISC_SUBCLASS_COMMON,

.bDeviceProtocol = MISC_PROTOCOL_IAD,

.bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE,

.idVendor = 0xCafe,

.idProduct = USB_PID,

.bcdDevice = 0x0100,

.iManufacturer = 0x01,

.iProduct = 0x02,

.iSerialNumber = 0x03,

.bNumConfigurations = 0x01

};

The following is the following callback audiod_tx_done_cb(), i am filling the USB linear buffer using global buffer readbuff as mention in the below image line number 1061 and 1062.

sidharth_seela_at_amantya_0-1748592308389.png

where, FillTxBuff is defined as follows;

bool FillTxBuff(void)

{

static int counter = 0;

TCHAR* rres = f_gets((TCHAR*)readBuf, 192, &fil);

if(rres != 0)

{

counter++;

}

else if((rres == 0) && (counter != 0))

{

f_close(&fil);

counter = 0;

}

else

{

Error_Handler();

}

}

SPECULATION: Somehow we feel that, prior to data transfer, there might be issues in handshaking clock/frequency data.

Thanks

Sidharth Seela