STM32F4系列DFU程序设计（HAL库）

一、前言

MCU的DFU功能，在产品中必不可少。本例通过USB接口进行ROM区域APP程序固件升级。所用的硬件为STM32F401 Discovery开发板。参考STM32CUBE中文网的文章 http://www.stm32cube.com/question/500

二、程序流程

2.1 Cube代码生成

Cube作为ST近年大力推行的初始化代码生成器，对于快速开发STM32程序还是很方便的，缺点是部分代码有些许BUG，调试起来不如标准库那样直观，毕竟封装的比较多。

转入正题，打开CUBE以后，选择好所用的MCU型号以后，在Pinout标签页左侧的MiddleWares中USB_DEVICE下设置为Download Frimware Update Class,即DFU模式，

时钟配置为外部时钟，然后Peripheerals下的USB_OTG_FS下设置为Device_Only，即USBD设备模式，（F4系列是支持USBH模式的)。OK这一页的设置完成。

转至USB-DEVICE configuration中设置APP区域的起始地址，以及BOOTLOADER占用的空间大小。

2.2 重写usbd_dfu_if.c

这个文件中是FLASH操作函数的实现，但是仅仅只有声明与函数体，具体实现没有完成需要用户去写。依次去看一下：

2.2.1 MEM_If_Init_FS

该函数的作用是初始化FLASH，将FLASH解锁，并将所有的标志位清零，以便后续的写入动作。

/**
  * @brief  MEM_If_Init_FS
  *         Memory initialization routine.
  * @param  None
  * @retval 0 if operation is successful, MAL_FAIL else.
  */
uint16_t MEM_If_Init_FS(void)
{  
	HAL_FLASH_Unlock();
	__HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR |
                           FLASH_FLAG_PGAERR | FLASH_FLAG_PGPERR | FLASH_FLAG_PGSERR);
  return (USBD_OK);
}

2.2.2 MEM_If_DeInit_FS

该函数与2.2.1的函数相对，将FLASH重新上锁，禁止对FLASH的操作

/**
  * @brief  MEM_If_DeInit_FS
  *         De-Initializes Memory.
  * @param  None
  * @retval 0 if operation is successful, MAL_FAIL else.
  */
uint16_t MEM_If_DeInit_FS(void)
{ 
	HAL_FLASH_Lock();
	return (USBD_OK);
}

2.2.3 GetSector

局部函数，初始代码中不含该函数，主要作用是返回用户起始区域的Sector地址，STM32F401内部FLASH根据芯片手册一共有6个，前4个为16K，第5个为64K，最后一个为128K

static uint32_t GetSector(uint32_t Address)
{
	uint32_t sector = 0;
	if((Address < ADDR_FLASH_SECTOR_1)&&(Address >= ADDR_FLASH_SECTOR_0))
	{
		sector = FLASH_SECTOR_0;
	}
	else if((Address < ADDR_FLASH_SECTOR_2)&&(Address >= ADDR_FLASH_SECTOR_1))
	{
		sector = FLASH_SECTOR_1;
	}
	else if((Address < ADDR_FLASH_SECTOR_3)&&(Address >= ADDR_FLASH_SECTOR_2))
	{
		sector = FLASH_SECTOR_2;
	}
	else if((Address < ADDR_FLASH_SECTOR_4)&&(Address >= ADDR_FLASH_SECTOR_3))
	{
		sector = FLASH_SECTOR_3;
	}
	else if((Address < ADDR_FLASH_SECTOR_5)&&(Address >= ADDR_FLASH_SECTOR_4))
	{
		sector = FLASH_SECTOR_4;
	}
	else 
	{
		sector = FLASH_SECTOR_5;
	}
	return sector;
}

2.2.4 MEM_If_Erase_FS

该函数实现的功能为擦除APP区域的数据，HAL库的初始化封装格式，定义了擦除方式为按照sector进行擦除，由于目前定义了前三个sector用于放置bootloader，所以APP区域的sector为3个，VoltageRange，3意味着电压范围为2.7V至3.6V。

/**
  * @brief  MEM_If_Erase_FS
  *         Erase sector.
  * @param  Add: Address of sector to be erased.
  * @retval 0 if operation is successful, MAL_FAIL else.
  */
uint16_t MEM_If_Erase_FS(uint32_t Add)
{
	uint32_t UserStartSector;
	uint32_t SectorError;
	FLASH_EraseInitTypeDef pEraseInit;
	MEM_If_Init_FS();
	UserStartSector = GetSector(Add);
	pEraseInit.TypeErase = TYPEERASE_SECTORS;
	pEraseInit.Sector = UserStartSector;
	pEraseInit.NbSectors = 3;
	pEraseInit.VoltageRange = VOLTAGE_RANGE_3;
	if(HAL_FLASHEx_Erase(&pEraseInit,&SectorError)!=HAL_OK)
	{
		return (USBD_FAIL);
	}	
	return (USBD_OK);
}

2.2.5 MEM_If_Write_FS

Flash写入的接口函数，将USB接收到的FLASH数据写入到FLASH中，也是比较关键的函数接口，以word为单位进行烧写

/**
  * @brief  MEM_If_Write_FS
  *         Memory write routine.
  * @param  src: Pointer to the source buffer. Address to be written to.
  * @param  dest: Pointer to the destination buffer.
  * @param  Len: Number of data to be written (in bytes).
  * @retval 0 if operation is successful, MAL_FAIL else.
  */
uint16_t MEM_If_Write_FS(uint8_t *src, uint8_t *dest, uint32_t Len)
{
	uint32_t i = 0;	
	for(i = 0; i < Len; i = i + 4)
	{
		if(HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD,(uint32_t)(dest + i),*(uint32_t *)(src + i)) == HAL_OK)
		{
			if(*(uint32_t *)(src + i) != *(uint32_t *)(dest + i))
			{
				return 2;
			}
		}
		else
		{
			return 1;
		}
	}	
  return (USBD_OK);
}

2.2.6 MEM_If_Read_FS

读取指定地址的数据 到目标数组中，并返回数组地址

/**
  * @brief  MEM_If_Read_FS
  *         Memory read routine.
  * @param  src: Pointer to the source buffer. Address to be written to.
  * @param  dest: Pointer to the destination buffer.
  * @param  Len: Number of data to be read (in bytes).
  * @retval Pointer to the physical address where data should be read.
  */
uint8_t *MEM_If_Read_FS (uint8_t *src, uint8_t *dest, uint32_t Len)
{
	uint32_t i = 0;
	uint8_t *psrc = src;
	for( i = 0; i < Len ; i++ )
	{
		dest[i] = *psrc++;
	}
	return (uint8_t *)(dest);
}

2.2.7 MEM_If_GetStatus_FS

返回状态

/**
  * @brief  Flash_If_GetStatus_FS
  *         Get status routine.
  * @param  Add: Address to be read from.
  * @param  Cmd: Number of data to be read (in bytes).
  * @param  buffer: used for returning the time necessary for a program or an erase operation
  * @retval 0 if operation is successful
  */
uint16_t MEM_If_GetStatus_FS (uint32_t Add, uint8_t Cmd, uint8_t *buffer)
{
	uint16_t FLASH_PROGRAM_TIME = 50;
	uint16_t FLASH_ERASE_TIME = 50;
	switch (Cmd)
	{
		case DFU_MEDIA_PROGRAM:
			buffer[1] = (uint8_t)FLASH_PROGRAM_TIME;
			buffer[2] = (uint8_t)(FLASH_PROGRAM_TIME << 8);
			buffer[3] = 0;
		break;
		case DFU_MEDIA_ERASE:
		default:
			buffer[1] = (uint8_t)FLASH_ERASE_TIME;
			buffer[2] = (uint8_t)(FLASH_ERASE_TIME << 8);
			buffer[3] = 0;
	break;
	}                             
  return  (USBD_OK);
}