STM32H743 USB device transmits zeros to the Host

[lw23]

Everything else is working fine.

Setup packet with SET_ADDRESS received and processed.

Next GET_DESCRIPTOR for DEVICE which is sent back ok 

I've verified the data written to the Tx FIFO is correct.

Correct number of bytes it transmitted but the bytes are not correct.

I'm using a STM32H743-EVAL board, hardware is working fine

Any suggestions?

p.s. the Device Descriptor received displayed by USB View

[FBL]

Hi @lw23 

Would you double-check the device descriptor data you are writing to the Tx FIFO. Ensure that all fields are correctly populated according to the USB specification. The bLength field should be 18 for a standard device descriptor.

[TDK]

Is data cache enabled? Disable it during the debugging stage. If that fixes it, you'll need to instrument your code with appropriate cache handling.

> I've verified the data written to the Tx FIFO is correct.

How, exactly?

[lw23]

I'm not using DMA, PIO only

void USB_WritePacket(USB_OTG_GlobalTypeDef *USBx,uint8_t *src, 
                     uint8_t ch_ep_num,uint16_t len)

{

 uint32_t USBx_BASE = (uint32_t)USBx;
 uint8_t *psrc=src;
 uint32_t count32b;
 uint32_t i;
 uint32_t data;

 count32b = ((uint32_t)len + 3U) / 4U;
 for (i = 0U; i < count32b; i++)
 {
    data = __UNALIGNED_UINT32_READ(pSrc);
    
    printf("%08X\n",data);
 
    USBx_DFIFO((uint32_t)ch_ep_num) = data;
    pSrc++;
    pSrc++;
    pSrc++;
    pSrc++;
 }

 return;
}

---

---

Produces this output

OTG_FS: DIEPTSIZ = 0x00080012
OTG_FS: DTXFSTS = 0x00000020
OTG_FS: 02000112
OTG_FS: 40000002
OTG_FS: 00190957
OTG_FS: 02010100
OTG_FS: 00000103
OTG_FS: DIEPTSIZ = 0x00080000
OTG_FS: DTXFSTS = 0x0000001B

XFRSIZ is correctly decremented to zero

FIFO space reduced by 5 words

 Thanks for the speed replies, I really appreciate it