miniF1的SD卡问题（蓝色为问题部分）

Ian22L · 发表于 2017-3-12 11:38:39

今天学习SD卡，发现FATFS例程的代码：
//其他表参数的获得
//drv:磁盘编号0~9
//ctrl:控制代码
//*buff:发送/接收缓冲区指针
#if _USE_IOCTL
DRESULT disk_ioctl (
BYTE pdrv, /* Physical drive nmuber (0..) */
BYTE cmd, /* Control code */
void *buff /* Buffer to send/receive control data */
)
{
DRESULT res;
if(pdrv==SD_CARD)//SD卡
{
      switch(cmd)
      {
      case CTRL_SYNC:
SD_CS=0;
         if(SD_WaitReady()==0)res = RES_OK;
         else res = RES_ERROR;
SD_CS=1;
         break;
      case GET_SECTOR_SIZE:
         *(WORD*)buff = 512;
         res = RES_OK;
         break;
      case GET_BLOCK_SIZE:
         *(WORD*)buff = 8;//SD卡的扇区不是一般512字节吗？为何此处设置擦出块大小为8？不应该设置为1？
         res = RES_OK;
         break;
      case GET_SECTOR_COUNT:
         *(DWORD*)buff = SD_GetSectorCount();
         res = RES_OK;
         break;
      default:
         res = RES_PARERR;
         break;
      }
}else if(pdrv==EX_FLASH) //外部FLASH
{
      switch(cmd)
      {
      case CTRL_SYNC:
res = RES_OK;
         break;
      case GET_SECTOR_SIZE:
         *(WORD*)buff = FLASH_SECTOR_SIZE;
         res = RES_OK;
         break;
      case GET_BLOCK_SIZE:
         *(WORD*)buff = FLASH_BLOCK_SIZE;
         res = RES_OK;
         break;
      case GET_SECTOR_COUNT:
         *(DWORD*)buff = FLASH_SECTOR_COUNT;
         res = RES_OK;
         break;
      default:
         res = RES_PARERR;
         break;
      }
}else res=RES_ERROR;//其他的不支持
return res;
}