Issue in downloading SD card data by USB

[Embedded_Engineer]

I am currently working on a project that involves integrating USB functionality for data transfer and data logging on an STM32F407VG micro-controller. Specifically, I want to log data files on an SD card and enable the user to download these logged files from the SD card via USB. Additionally, I'd like to allow users to copy files from their PC to the SD card via USB, all through the STM32F407VG using the SDIO communication protocol.

I'm facing a challenge in making the USB_OTG_FS (On-The-Go Full Speed USB) and the SD card (using FatFS) work together seamlessly. I would greatly appreciate your guidance and any insights you might have on how to achieve this integration.

Here are some specific questions I have:

1. How do I configure USB_OTG_FS as a USB Device in STM32CubeMX or other development tools?
2. What are the essential initialization and setup steps for using the USB_OTG_FS as a USB Device alongside the FatFS library for SD card communication?
3. Are there any sample code snippets or project examples that demonstrate this integration?
4. What should I be mindful of when managing the data transfer between the USB and SD card to avoid conflicts or data corruption?

Here is my code:

#include "usbd_storage_if.h"

extern SD_HandleTypeDef hsd;

#define STORAGE_LUN_NBR 1
#define STORAGE_BLK_NBR 0x10000
#define STORAGE_BLK_SIZ 0x200

const int8_t STORAGE_Inquirydata_FS[] = {

0x00,
0x80,
0x02,
0x02,
(STANDARD_INQUIRY_DATA_LEN - 5),
0x00,
0x00,
0x00,
'S', 'T', 'M', ' ', ' ', ' ', ' ', ' ', /* Manufacturer : 8 bytes */
'P', 'r', 'o', 'd', 'u', 'c', 't', ' ', /* Product : 16 Bytes */
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ',
'0', '.', '0' ,'1' /* Version : 4 Bytes */
};

static int8_t STORAGE_Init_FS(uint8_t lun);
static int8_t STORAGE_GetCapacity_FS(uint8_t lun, uint32_t *block_num, uint16_t *block_size);
static int8_t STORAGE_IsReady_FS(uint8_t lun);
static int8_t STORAGE_IsWriteProtected_FS(uint8_t lun);
static int8_t STORAGE_Read_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len);
static int8_t STORAGE_Write_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len);
static int8_t STORAGE_GetMaxLun_FS(void);

USBD_StorageTypeDef USBD_Storage_Interface_fops_FS =
{
STORAGE_Init_FS,
STORAGE_GetCapacity_FS,
STORAGE_IsReady_FS,
STORAGE_IsWriteProtected_FS,
STORAGE_Read_FS,
STORAGE_Write_FS,
STORAGE_GetMaxLun_FS,
(int8_t *)STORAGE_Inquirydata_FS
};

int8_t STORAGE_Init_FS(uint8_t lun)
{

return (USBD_OK);

}

int8_t STORAGE_GetCapacity_FS(uint8_t lun, uint32_t *block_num, uint16_t *block_size)
{

HAL_SD_CardInfoTypeDef info;
int8_t ret = -1;

HAL_SD_GetCardInfo(&hsd, &info);

*block_num = info.LogBlockNbr - 1;
*block_size = info.LogBlockSize;
ret = 0;
return ret;

}

int8_t STORAGE_IsReady_FS(uint8_t lun)
{

return (USBD_OK);

}

int8_t STORAGE_IsWriteProtected_FS(uint8_t lun)
{

return (USBD_OK);

}

int8_t STORAGE_Read_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{

int8_t ret = -1;

HAL_SD_ReadBlocks(&hsd, buf, blk_addr, blk_len, HAL_MAX_DELAY);

/* Wait until SD card is ready to use for new operation */
while (HAL_SD_GetCardState(&hsd) != HAL_SD_CARD_TRANSFER){}
ret = 0;
return ret;

}

int8_t STORAGE_Write_FS(uint8_t lun, uint8_t *buf, uint32_t blk_addr, uint16_t blk_len)
{

int8_t ret = -1;

HAL_SD_WriteBlocks(&hsd, buf, blk_addr, blk_len, HAL_MAX_DELAY);

while (HAL_SD_GetCardState(&hsd) != HAL_SD_CARD_TRANSFER){}
ret = 0;
return ret;

}

int8_t STORAGE_GetMaxLun_FS(void)
{

return (STORAGE_LUN_NBR - 1);

}