来源：项目中需要用stm32对外部spi flash（m25p16  2MB）进行快速读取，主要是图像数据。

平台：stm32f407---168MHz，FreeRTOS V7.3.0 

主要参考：http://blog.csdn.net/sinat_20598829/article/details/44408125

貌似发现了其中的一个小问题，未使用中断！！！见图

期间还参考帖子：http://blog.csdn.net/chenwei2002/article/details/49722373，本人不才，未能实现文中使用的方法。对于文中所讲：我们把SPI模式配置成只读模式，如上面程序中的样子，这个时候就可以直接读取数据，而不需要在发送无效数据0xff，大大提高了性能。SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_RxOnly; 然而在配置为只读模式后没有spi时钟驱动flash进行数据输出，故放弃此方法。

代码来源：st 官方spi flash驱动文件

（STM32F4xx_DSP_StdPeriph_Lib_V1.4.0ProjectSTM32F4xx_StdPeriph_ExamplesSPISPI_FLASH）

在官方文件的基础上进行修改（注意修改红色部分）：

/**

  ******************************************************************************

  *

  *          +-----------------------------------------------------------+

  *          |                     Pin assignment                        |

  *          +-----------------------------+---------------+-------------+

  *          |  STM32 SPI Pins             |     sFLASH    |    Pin      |

  *          +-----------------------------+---------------+-------------+

  *          | sFLASH_CS_PIN               | ChipSelect(/S)|    1        |

  *          | sFLASh_SPI_MISO_PIN / MISO  |   DataOut(Q)  |    2        |

  *          |                             |   VCC         |    3 (3.3 V)|

  *          |                             |   GND         |    4 (0 V)  |

  *          | sFLASH_SPI_MOSI_PIN / MOSI  |   DataIn(D)   |    5        |

  *          | sFLASH_SPI_SCK_PIN / SCK    |   Clock(C)    |    6        |

  *          |                             |    VCC        |    7 (3.3 V)|

  *          |                             |    VCC        |    8 (3.3 V)|

  *          +-----------------------------+---------------+-------------+

  ******************************************************************************

  * @attention

  * 

  ******************************************************************************

  */

/* Includes ------------------------------------------------------------------*/

#include "spi_dma_flash.h"

#include

/** @addtogroup STM32F4xx_StdPeriph_Examples

  * @{

  */

/** @addtogroup SPI_FLASH

  * @{

  */

/* Private typedef -----------------------------------------------------------*/

/* Private define ------------------------------------------------------------*/

#define USE_SPI_DMA

#define SET_SPI1_ENABLE     SPI_Cmd(sFLASH_DMA_SPI, ENABLE);

#define DMA2_TX_STREAM      DMA2_Stream3

#define DMA2_TX_CHANNEL     DMA_Channel_3

#define DMA2_RX_STREAM      DMA2_Stream0

#define DMA2_RX_CHANNEL     DMA_Channel_3

/* Private macro -------------------------------------------------------------*/

/* Private variables ---------------------------------------------------------*/

static DMA_InitTypeDef DMA2_Tx_InitStructure;

static DMA_InitTypeDef DMA2_Rx_InitStructure;

/* Private function prototypes -----------------------------------------------*/

void sFLASH_DMA_LowLevel_DeInit(void);

void sFLASH_DMA_LowLevel_Init(void);

/* Private functions ---------------------------------------------------------*/

/**

  * @brief  DeInitializes the peripherals used by the SPI FLASH driver.

  * @param  None

  * @retval None

  */

void sFLASH_DMA_DeInit(void)

{

  sFLASH_DMA_LowLevel_DeInit();

}

/**

  * @brief  Initializes the peripherals used by the SPI FLASH driver.

  * @param  None

  * @retval None

  */

void sFLASH_DMA_Init(void)

{

  SPI_InitTypeDef  SPI_InitStructure;

  sFLASH_DMA_LowLevel_Init();

  /*!< Deselect the FLASH: Chip Select high */

  sFLASH_DMA_CS_HIGH();

  /*!< SPI configuration */

  SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;

  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;

  SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;

  SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;

  SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;

  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;

  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;

  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;

  SPI_InitStructure.SPI_CRCPolynomial = 7;

  DMA_Configuration_SPI1();

  SPI_Init(sFLASH_DMA_SPI, &SPI_InitStructure); 

  SET_SPI1_ENABLE;

}

/**

  * @brief  Erases the specified FLASH sector.

  * @param  SectorAddr: address of the sector to erase.

  * @retval None

  */

void sFLASH_DMA_EraseSector(uint32_t SectorAddr)

{

  /*!< Send write enable instruction */

  sFLASH_DMA_WriteEnable();

  /*!< Sector Erase */

  /*!< Select the FLASH: Chip Select low */

  sFLASH_DMA_CS_LOW();

  /*!< Send Sector Erase instruction */

  sFLASH_DMA_SendByte(sFLASH_DMA_CMD_SE);

  /*!< Send SectorAddr high nibble address byte */

  sFLASH_DMA_SendByte((SectorAddr & 0xFF0000) >> 16);

  /*!< Send SectorAddr medium nibble address byte */

  sFLASH_DMA_SendByte((SectorAddr & 0xFF00) >> 8);

  /*!< Send SectorAddr low nibble address byte */

  sFLASH_DMA_SendByte(SectorAddr & 0xFF);

  /*!< Deselect the FLASH: Chip Select high */

  sFLASH_DMA_CS_HIGH();

  /*!< Wait the end of Flash writing */

  sFLASH_DMA_WaitForWriteEnd();

}

/**

  * @brief  Erases the entire FLASH.

  * @param  None

  * @retval None

  */

void sFLASH_DMA_EraseBulk(void)

{

  /*!< Send write enable instruction */

  sFLASH_DMA_WriteEnable();

  /*!< Bulk Erase */

  /*!< Select the FLASH: Chip Select low */

  sFLASH_DMA_CS_LOW();

  /*!< Send Bulk Erase instruction  */

  sFLASH_DMA_SendByte(sFLASH_DMA_CMD_BE);

  /*!< Deselect the FLASH: Chip Select high */

  sFLASH_DMA_CS_HIGH();

  /*!< Wait the end of Flash writing */

  sFLASH_DMA_WaitForWriteEnd();

}

/**

  * @brief  Writes more than one byte to the FLASH with a single WRITE cycle

  *         (Page WRITE sequence).

  * @note   The number of byte can't exceed the FLASH page size.

  * @param  pBuffer: pointer to the buffer  containing the data to be written

  *         to the FLASH.

  * @param  WriteAddr: FLASH's internal address to write to.

  * @param  NumByteToWrite: number of bytes to write to the FLASH, must be equal

  *         or less than "sFLASH_DMA_PAGESIZE" value.

  * @retval None

  */

void sFLASH_DMA_WritePage(uint8_t* pBuffer, uint32_t WriteAddr, uint16_t NumByteToWrite)

{

  /*!< Enable the write access to the FLASH */

  sFLASH_DMA_WriteEnable();

  /*!< Select the FLASH: Chip Select low */

  sFLASH_DMA_CS_LOW();

  /*!< Send "Write to Memory " instruction */

  sFLASH_DMA_SendByte(sFLASH_DMA_CMD_WRITE);

  /*!< Send WriteAddr high nibble address byte to write to */

  sFLASH_DMA_SendByte((WriteAddr & 0xFF0000) >> 16);

  /*!< Send WriteAddr medium nibble address byte to write to */

  sFLASH_DMA_SendByte((WriteAddr & 0xFF00) >> 8);

  /*!< Send WriteAddr low nibble address byte to write to */

  sFLASH_DMA_SendByte(WriteAddr & 0xFF);

  /*!< while there is data to be written on the FLASH */

  while (NumByteToWrite--)

  {

    /*!< Send the current byte */

    sFLASH_DMA_SendByte(*pBuffer);

    /*!< Point on the next byte to be written */

    pBuffer++;

  } 

  /*!< Deselect the FLASH: Chip Select high */

  sFLASH_DMA_CS_HIGH();

  /*!< Wait the end of Flash writing */

  sFLASH_DMA_WaitForWriteEnd();

}

/**

  * @brief  Writes block of data to the FLASH. In this function, the number of

  *         WRITE cycles are reduced, using Page WRITE sequence.

  * @param  pBuffer: pointer to the buffer  containing the data to be written

  *         to the FLASH.

* @param WriteAddr: FLASH's