帮我用stm32的hal库写一个u盘读写的函数

好的，下面是一个简单的示例代码，用于在STM32上使用HAL库读写U盘： ```c #include "stm32f4xx_hal.h" #include "usb_host.h" #define USB_BUFFER_SIZE 512 USBH_HandleTypeDef hUsbHostFS; uint8_t usbBuffer[USB_BUFFER_SIZE]; void USBH_UserProcess(USBH_HandleTypeDef *phost, uint8_t id) { switch(id) { case HOST_USER_SELECT_CONFIGURATION: break; case HOST_USER_DISCONNECTION: break; default: break; } } void USBH_Init(void) { USBH_StatusTypeDef status = USBH_OK; /* Init Host Library */ USBH_Init(&hUsbHostFS, USBH_UserProcess, 0); /* Add Supported Class */ USBH_RegisterClass(&hUsbHostFS, USBH_MSC_CLASS); /* Start Host Process */ USBH_Start(&hUsbHostFS); /* Wait until device is connected */ while((status = USBH_GetStatus(&hUsbHostFS)) == USBH_BUSY); if(status == USBH_OK) { /* Device Connected */ printf("Device Connected\n"); /* Configure MSC */ USBH_MSC_HandleTypeDef *MSC_Handle = (USBH_MSC_HandleTypeDef*)hUsbHostFS.pActiveClass->pData; MSC_Handle->unit[0].capacity = 0; MSC_Handle->unit[0].block_size = 0; MSC_Handle->unit[0].last_lba = 0; MSC_Handle->unit[0].state = USBH_MSC_UNIT_READY; } else { /* Device Not Connected */ printf("Device Not Connected\n"); } } int USBH_ReadFile(char *filename, uint8_t *data, uint32_t size) { USBH_StatusTypeDef status = USBH_OK; /* Open File */ if(f_open(&USBH_MSC_fatfs, filename, FA_READ) != FR_OK) { printf("Failed to open file: %s\n", filename); return -1; } /* Read Data */ if(f_read(&USBH_MSC_fatfs, data, size, (UINT*)&status) != FR_OK) { printf("Failed to