i am trying to interface a serial flash (m25p80) using the spi protocol with the stm32f4 discovery board. This is the code that i am using...i am unable to figure out what is the problem...
#include "stm32f4_discovery.h"
#define SPI_PORT                  SPI2
#define SPI_PORT_CLOCK            RCC_APB1Periph_SPI2
#define SPI_PORT_CLOCK_INIT       RCC_APB1PeriphClockCmd


#define SPI_NSS_PIN              GPIO_Pin_12
#define SPI_NSS_GPIO_PORT        GPIOB
#define SPI_NSS_GPIO_CLK         RCC_AHB1Periph_GPIOB
#define SPI_NSS_SOURCE           GPIO_PinSource12
#define SPI_NSS_AF               GPIO_AF_SPI2


 
#define SPI_SCK_PIN              GPIO_Pin_13
#define SPI_SCK_GPIO_PORT        GPIOB
#define SPI_SCK_GPIO_CLK         RCC_AHB1Periph_GPIOB
#define SPI_SCK_SOURCE           GPIO_PinSource13
#define SPI_SCK_AF               GPIO_AF_SPI2
 
#define SPI_MOSI_PIN             GPIO_Pin_15
#define SPI_MOSI_GPIO_PORT       GPIOB
#define SPI_MOSI_GPIO_CLK        RCC_AHB1Periph_GPIOB
#define SPI_MOSI_SOURCE          GPIO_PinSource15
#define SPI_MOSI_AF              GPIO_AF_SPI2


#define SPI_MISO_PIN             GPIO_Pin_14
#define SPI_MISO_GPIO_PORT       GPIOB
#define SPI_MISO_GPIO_CLK        RCC_AHB1Periph_GPIOB
#define SPI_MISO_SOURCE          GPIO_PinSource14
#define SPI_MISO_AF              GPIO_AF_SPI2




/** @addtogroup STM32F4_Discovery_Peripheral_Examples
  * @{
  */


/** @addtogroup RCC_Example
  * @{
  */ 


/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/ 
/* Private function prototypes -----------------------------------------------*/
void Delay (uint32_t nCount);
void HardwareSPI_init(void);
void spiPutWord(uint16_t data);
uint16_t spiGetWord(void) ;
uint16_t a;
//uint16_t datawrite[10]={0x12,0x11,0x10,0x09,0x08,0x07,0x06,0x05,0x04,0x03},dataread[10]={0},i,j;
/* Private functions ---------------------------------------------------------*/


/**
  * @brief   Main program
  * @param  None
  * @retval None
  */
typedef enum {FAILED = 0, PASSED = !FAILED} TestStatus;
#define  FLASH_WRITE_ADDRESS      0x70000
#define  FLASH_WRITE_ADDRESS_test      0x60000
#define  FLASH_READ_ADDRESS       FLASH_WRITE_ADDRESS
#define  FLASH_READ_ADDRESS_test      FLASH_WRITE_ADDRESS_test
#define  FLASH_SECTOR_TO_ERASE    FLASH_WRITE_ADDRESS
#define  FLASH_SECTOR_TO_ERASE_test   FLASH_WRITE_ADDRESS_test


#define  BufferSize (countof(Tx_Buffer)-1)
#define  BufferSize_test (countof(Tx_Buffer1)-1)


/* Private macro -------------------------------------------------------------*/
#define countof(a) (sizeof(a) / sizeof(*(a)))


/* Private variables ---------------------------------------------------------*/
uint8_t Tx_Buffer[] = "STM32F4xx SPI Firmware Library Example: communication with an M25P SPI FLASH";
uint8_t Tx_Buffer1[] ={0xfb,0xfc};
uint8_t  Rx_Buffer[BufferSize];
uint8_t Rx_Buffer1[]={0,0};
__IO uint8_t Index = 0x0;
volatile TestStatus TransferStatus1 = FAILED, TransferStatus2 = PASSED;
__IO uint32_t FlashID = 0xfa;


/* Private functions ---------------------------------------------------------*/
TestStatus Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength);
int main(void)
{    

  GPIO_InitTypeDef GPIO_InitStructure;
/* GPIOD Periph clock enable */
 // RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);


  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
GPIO_ResetBits(GPIOB, GPIO_Pin_12);


  /* Configure PD12, PD13, PD14 and PD15 in output pushpull mode */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13| GPIO_Pin_14| GPIO_Pin_15;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOD, &GPIO_InitStructure);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
  //GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  //GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
STM_EVAL_PBInit(BUTTON_USER, BUTTON_MODE_GPIO);


         HardwareSPI_init();

sFLASH_Init();

sFLASH_EraseSector(FLASH_SECTOR_TO_ERASE);
sFLASH_EraseSector(FLASH_SECTOR_TO_ERASE_test);
/* Get SPI Flash ID */
  FlashID = sFLASH_ReadID();
//GPIO_SetBits(GPIOD, GPIO_Pin_13);
    /* Write Tx_Buffer data to SPI FLASH memory */
if(  FlashID ==0x00)
{

sFLASH_WriteBuffer(Tx_Buffer1, FLASH_WRITE_ADDRESS_test, BufferSize_test);
 spiPutWord(0x0000); //dummy write to get clock cycles
sFLASH_ReadBuffer(Rx_Buffer1, FLASH_READ_ADDRESS_test, BufferSize_test);
if(Rx_Buffer1[0]==Tx_Buffer1[0] && Rx_Buffer1[1]==Tx_Buffer[1])
{

sFLASH_WriteBuffer(Tx_Buffer, FLASH_WRITE_ADDRESS, BufferSize);
GPIO_SetBits(GPIOD, GPIO_Pin_12);
    /* Read data from SPI FLASH memory */
spiPutWord(0x0000); //dummy write to get clock cycles
    sFLASH_ReadBuffer(Rx_Buffer, FLASH_READ_ADDRESS, BufferSize);
if(*Rx_Buffer != 0xff)
GPIO_SetBits(GPIOD, GPIO_Pin_13);
    /* Check the correctness of written dada */
    TransferStatus1 = Buffercmp(Tx_Buffer, Rx_Buffer, BufferSize);
if(TransferStatus1 == PASSED)
{
GPIO_SetBits(GPIOD, GPIO_Pin_14);
}
else
{
GPIO_SetBits(GPIOD, GPIO_Pin_15);
}
//GPIO_SetBits(GPIOB, GPIO_Pin_13);
  }
else
{
GPIO_SetBits(GPIOD, GPIO_Pin_12);
GPIO_SetBits(GPIOD, GPIO_Pin_13);
GPIO_SetBits(GPIOD, GPIO_Pin_14);
GPIO_SetBits(GPIOD, GPIO_Pin_15);
}
while (1)

  {}
}
void HardwareSPI_init(void) 
{

  uint8_t spiConfigured;
  SPI_InitTypeDef SPI_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;
  // enable the SPI peripheral clock
  SPI_PORT_CLOCK_INIT(SPI_PORT_CLOCK, ENABLE);
  // enable the peripheral GPIO port clocks
  RCC_AHB1PeriphClockCmd(SPI_SCK_GPIO_CLK | SPI_MOSI_GPIO_CLK|SPI_MISO_GPIO_CLK , ENABLE);
  // Connect SPI pins to AF5 - see section 3, Table 6 in the device datasheet
//GPIO_PinAFConfig(SPI_NSS_GPIO_PORT, SPI_NSS_SOURCE, SPI_NSS_AF);
  GPIO_PinAFConfig(SPI_SCK_GPIO_PORT, SPI_SCK_SOURCE, SPI_SCK_AF);
  GPIO_PinAFConfig(SPI_MOSI_GPIO_PORT, SPI_MOSI_SOURCE, SPI_MOSI_AF);
GPIO_PinAFConfig(SPI_MISO_GPIO_PORT, SPI_MISO_SOURCE, SPI_MISO_AF);
  // now configure the pins themselves
  // they are all going to be fast push-pull outputs
  // but the SPI pins use the alternate function
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_25MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

// GPIO_InitStructure.GPIO_Pin = SPI_NSS_PIN;
  //GPIO_Init(SPI_NSS_GPIO_PORT, &GPIO_InitStructure);
  GPIO_InitStructure.GPIO_Pin = SPI_SCK_PIN;
  GPIO_Init(SPI_SCK_GPIO_PORT, &GPIO_InitStructure);
  GPIO_InitStructure.GPIO_Pin = SPI_MOSI_PIN;
  GPIO_Init(SPI_MOSI_GPIO_PORT, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = SPI_MISO_PIN;
  GPIO_Init(SPI_MISO_GPIO_PORT, &GPIO_InitStructure);
  // now we can set up the SPI peripheral
  // Assume the target is write only and we look after the chip select ourselves
  // SPI clock rate will be system frequency/4/prescaler
  // so here we will go for 72/4/8 = 2.25MHz
  SPI_I2S_DeInit(SPI_PORT);
  SPI_StructInit(&SPI_InitStructure);
  SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
  SPI_InitStructure.SPI_Direction =SPI_Direction_2Lines_FullDuplex ;

SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
  SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
  SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;
  SPI_Init(SPI_PORT, &SPI_InitStructure);
  // Enable the SPI port
  SPI_Cmd(SPI_PORT, ENABLE);
  spiConfigured = 1;
}




void spiPutWord(uint16_t data)
{
  // make sure the transmit buffer is free
  while (SPI_I2S_GetFlagStatus(SPI_PORT, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(SPI2, data);
 
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_BSY) == SET);
};


uint16_t spiGetWord(void) 
{ STM_EVAL_LEDOn(LED6);
Delay(0xffff);
  // make sure the transmit buffer is free
  while (SPI_I2S_GetFlagStatus(SPI_PORT, SPI_I2S_FLAG_RXNE) == RESET);
  STM_EVAL_LEDOff(LED6);
 
  while (SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_BSY) == SET);
STM_EVAL_LEDOff(LED5);
return SPI_I2S_ReceiveData(SPI2);
};
/**
  * @brief  Inserts a delay time.
  * @param  nCount: specifies the delay time length.
  * @retval None
  */
void Delay(__IO uint32_t nCount)
{
  /* Decrement nCount value */
  while (nCount != 0)
  {
    nCount--;
  }
}
TestStatus Buffercmp(uint8_t* pBuffer1, uint8_t* pBuffer2, uint16_t BufferLength)
{
  while (BufferLength--)
  {
    if (*pBuffer1 != *pBuffer2)
    {
      return FAILED;
    }


    pBuffer1++;
    pBuffer2++;
  }


  return PASSED;
} 
the function descriptions are as follows:
void sFLASH_DeInit(void)
{
  sFLASH_LowLevel_DeInit();
}


/**
  * @brief  Initializes the peripherals used by the SPI FLASH driver.
  * @param  None
  * @retval None
  */
void sFLASH_Init(void)
{
  SPI_InitTypeDef  SPI_InitStructure;


  sFLASH_LowLevel_Init();
    
  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_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_4;


  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(sFLASH_SPI, &SPI_InitStructure);


  /*!< Enable the sFLASH_SPI  */
  SPI_Cmd(sFLASH_SPI, ENABLE);
}


/**
  * @brief  Erases the specified FLASH sector.
  * @param  SectorAddr: address of the sector to erase.
  * @retval None
  */
void sFLASH_EraseSector(uint32_t SectorAddr)
{
  /*!< Send write enable instruction */
  sFLASH_WriteEnable();


  /*!< Sector Erase */
  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();
  /*!< Send Sector Erase instruction */
  sFLASH_SendByte(sFLASH_CMD_SE);
  /*!< Send SectorAddr high nibble address byte */
  sFLASH_SendByte((SectorAddr & 0xFF0000) >> 16);
  /*!< Send SectorAddr medium nibble address byte */
  sFLASH_SendByte((SectorAddr & 0xFF00) >> 8);
  /*!< Send SectorAddr low nibble address byte */
  sFLASH_SendByte(SectorAddr & 0xFF);
  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();


  /*!< Wait the end of Flash writing */
  sFLASH_WaitForWriteEnd();
}


/**
  * @brief  Erases the entire FLASH.
  * @param  None
  * @retval None
  */
void sFLASH_EraseBulk(void)
{
  /*!< Send write enable instruction */
  sFLASH_WriteEnable();


  /*!< Bulk Erase */
  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();
  /*!< Send Bulk Erase instruction  */
  sFLASH_SendByte(sFLASH_CMD_BE);
  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();


  /*!< Wait the end of Flash writing */
  sFLASH_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_PAGESIZE" value.
  * @retval None
  */
void sFLASH_WritePage(uint8_t* pBuffer, uint32_t WriteAddr, uint16_t NumByteToWrite)
{
  /*!< Enable the write access to the FLASH */
  sFLASH_WriteEnable();


  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();
  /*!< Send "Write to Memory " instruction */
  sFLASH_SendByte(sFLASH_CMD_WRITE);
  /*!< Send WriteAddr high nibble address byte to write to */
  sFLASH_SendByte((WriteAddr & 0xFF0000) >> 16);
  /*!< Send WriteAddr medium nibble address byte to write to */
  sFLASH_SendByte((WriteAddr & 0xFF00) >> 8);
  /*!< Send WriteAddr low nibble address byte to write to */
  sFLASH_SendByte(WriteAddr & 0xFF);


  /*!< while there is data to be written on the FLASH */
  while (NumByteToWrite--)
  {
    /*!< Send the current byte */
    sFLASH_SendByte(*pBuffer);
    /*!< Point on the next byte to be written */
    pBuffer++;
  }


  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();


  /*!< Wait the end of Flash writing */
  sFLASH_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 internal address to write to.
  * @param  NumByteToWrite: number of bytes to write to the FLASH.
  * @retval None
  */
void sFLASH_WriteBuffer(uint8_t* pBuffer, uint32_t WriteAddr, uint16_t NumByteToWrite)
{
  uint8_t NumOfPage = 0, NumOfSingle = 0, Addr = 0, count = 0, temp = 0;


  Addr = WriteAddr % sFLASH_SPI_PAGESIZE;
  count = sFLASH_SPI_PAGESIZE - Addr;
  NumOfPage =  NumByteToWrite / sFLASH_SPI_PAGESIZE;
  NumOfSingle = NumByteToWrite % sFLASH_SPI_PAGESIZE;


  if (Addr == 0) /*!< WriteAddr is sFLASH_PAGESIZE aligned  */
  {
    if (NumOfPage == 0) /*!< NumByteToWrite < sFLASH_PAGESIZE */
    {
      sFLASH_WritePage(pBuffer, WriteAddr, NumByteToWrite);
    }
    else /*!< NumByteToWrite > sFLASH_PAGESIZE */
    {
      while (NumOfPage--)
      {
        sFLASH_WritePage(pBuffer, WriteAddr, sFLASH_SPI_PAGESIZE);
        WriteAddr +=  sFLASH_SPI_PAGESIZE;
        pBuffer += sFLASH_SPI_PAGESIZE;
      }


      sFLASH_WritePage(pBuffer, WriteAddr, NumOfSingle);
    }
  }
  else /*!< WriteAddr is not sFLASH_PAGESIZE aligned  */
  {
    if (NumOfPage == 0) /*!< NumByteToWrite < sFLASH_PAGESIZE */
    {
      if (NumOfSingle > count) /*!< (NumByteToWrite + WriteAddr) > sFLASH_PAGESIZE */
      {
        temp = NumOfSingle - count;


        sFLASH_WritePage(pBuffer, WriteAddr, count);
        WriteAddr +=  count;
        pBuffer += count;


        sFLASH_WritePage(pBuffer, WriteAddr, temp);
      }
      else
      {
        sFLASH_WritePage(pBuffer, WriteAddr, NumByteToWrite);
      }
    }
    else /*!< NumByteToWrite > sFLASH_PAGESIZE */
    {
      NumByteToWrite -= count;
      NumOfPage =  NumByteToWrite / sFLASH_SPI_PAGESIZE;
      NumOfSingle = NumByteToWrite % sFLASH_SPI_PAGESIZE;


      sFLASH_WritePage(pBuffer, WriteAddr, count);
      WriteAddr +=  count;
      pBuffer += count;


      while (NumOfPage--)
      {
        sFLASH_WritePage(pBuffer, WriteAddr, sFLASH_SPI_PAGESIZE);
        WriteAddr +=  sFLASH_SPI_PAGESIZE;
        pBuffer += sFLASH_SPI_PAGESIZE;
      }


      if (NumOfSingle != 0)
      {
        sFLASH_WritePage(pBuffer, WriteAddr, NumOfSingle);
      }
    }
  }
}


/**
  * @brief  Reads a block of data from the FLASH.
  * @param  pBuffer: pointer to the buffer that receives the data read from the FLASH.
  * @param  ReadAddr: FLASH's internal address to read from.
  * @param  NumByteToRead: number of bytes to read from the FLASH.
  * @retval None
  */
void sFLASH_ReadBuffer(uint8_t* pBuffer, uint32_t ReadAddr, uint16_t NumByteToRead)
{
  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();


  /*!< Send "Read from Memory " instruction */
  sFLASH_SendByte(sFLASH_CMD_READ);


  /*!< Send ReadAddr high nibble address byte to read from */
  sFLASH_SendByte((ReadAddr & 0xFF0000) >> 16);
  /*!< Send ReadAddr medium nibble address byte to read from */
  sFLASH_SendByte((ReadAddr& 0xFF00) >> 8);
  /*!< Send ReadAddr low nibble address byte to read from */
  sFLASH_SendByte(ReadAddr & 0xFF);


  while (NumByteToRead--) /*!< while there is data to be read */
  {
    /*!< Read a byte from the FLASH */
    *pBuffer = sFLASH_SendByte(sFLASH_DUMMY_BYTE);
    /*!< Point to the next location where the byte read will be saved */
    pBuffer++;
  }


  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();
}


/**
  * @brief  Reads FLASH identification.
  * @param  None
  * @retval FLASH identification
  */
uint32_t sFLASH_ReadID(void)
{
  uint32_t Temp = 0, Temp0 = 0, Temp1 = 0, Temp2 = 0;


  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();


  /*!< Send "RDID " instruction */
  sFLASH_SendByte(0x9F);


  /*!< Read a byte from the FLASH */
  Temp0 = sFLASH_SendByte(sFLASH_DUMMY_BYTE);


  /*!< Read a byte from the FLASH */
  Temp1 = sFLASH_SendByte(sFLASH_DUMMY_BYTE);


  /*!< Read a byte from the FLASH */
  Temp2 = sFLASH_SendByte(sFLASH_DUMMY_BYTE);


  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();


  Temp = (Temp0 << 16) | (Temp1 << 8) | Temp2;


  return Temp;
}


/**
  * @brief  Initiates a read data byte (READ) sequence from the Flash.
  *   This is done by driving the /CS line low to select the device, then the READ
  *   instruction is transmitted followed by 3 bytes address. This function exit
  *   and keep the /CS line low, so the Flash still being selected. With this
  *   technique the whole content of the Flash is read with a single READ instruction.
  * @param  ReadAddr: FLASH's internal address to read from.
  * @retval None
  */
void sFLASH_StartReadSequence(uint32_t ReadAddr)
{
  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();


  /*!< Send "Read from Memory " instruction */
  sFLASH_SendByte(sFLASH_CMD_READ);


  /*!< Send the 24-bit address of the address to read from -------------------*/
  /*!< Send ReadAddr high nibble address byte */
  sFLASH_SendByte((ReadAddr & 0xFF0000) >> 16);
  /*!< Send ReadAddr medium nibble address byte */
  sFLASH_SendByte((ReadAddr& 0xFF00) >> 8);
  /*!< Send ReadAddr low nibble address byte */
  sFLASH_SendByte(ReadAddr & 0xFF);
}


/**
  * @brief  Reads a byte from the SPI Flash.
  * @note   This function must be used only if the Start_Read_Sequence function
  *         has been previously called.
  * @param  None
  * @retval Byte Read from the SPI Flash.
  */
uint8_t sFLASH_ReadByte(void)
{
  return (sFLASH_SendByte(sFLASH_DUMMY_BYTE));
}


/**
  * @brief  Sends a byte through the SPI interface and return the byte received
  *         from the SPI bus.
  * @param  byte: byte to send.
  * @retval The value of the received byte.
  */
uint8_t sFLASH_SendByte(uint8_t byte)
{
  /*!< Loop while DR register in not emplty */
  while (SPI_I2S_GetFlagStatus(sFLASH_SPI, SPI_I2S_FLAG_TXE) == RESET);


  /*!< Send byte through the SPI1 peripheral */
  SPI_I2S_SendData(sFLASH_SPI, byte);


  /*!< Wait to receive a byte */
  while (SPI_I2S_GetFlagStatus(sFLASH_SPI, SPI_I2S_FLAG_RXNE) == RESET);


  /*!< Return the byte read from the SPI bus */
  return SPI_I2S_ReceiveData(sFLASH_SPI);
}


/**
  * @brief  Sends a Half Word through the SPI interface and return the Half Word
  *         received from the SPI bus.
  * @param  HalfWord: Half Word to send.
  * @retval The value of the received Half Word.
  */
uint16_t sFLASH_SendHalfWord(uint16_t HalfWord)
{
  /*!< Loop while DR register in not emplty */
  while (SPI_I2S_GetFlagStatus(sFLASH_SPI, SPI_I2S_FLAG_TXE) == RESET);


  /*!< Send Half Word through the sFLASH peripheral */
  SPI_I2S_SendData(sFLASH_SPI, HalfWord);


  /*!< Wait to receive a Half Word */
  while (SPI_I2S_GetFlagStatus(sFLASH_SPI, SPI_I2S_FLAG_RXNE) == RESET);


  /*!< Return the Half Word read from the SPI bus */
  return SPI_I2S_ReceiveData(sFLASH_SPI);
}


/**
  * @brief  Enables the write access to the FLASH.
  * @param  None
  * @retval None
  */
void sFLASH_WriteEnable(void)
{
  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();


  /*!< Send "Write Enable" instruction */
  sFLASH_SendByte(sFLASH_CMD_WREN);


  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();
}


/**
  * @brief  Polls the status of the Write In Progress (WIP) flag in the FLASH's
  *         status register and loop until write opertaion has completed.
  * @param  None
  * @retval None
  */
void sFLASH_WaitForWriteEnd(void)
{
  uint8_t flashstatus = 0;


  /*!< Select the FLASH: Chip Select low */
  sFLASH_CS_LOW();


  /*!< Send "Read Status Register" instruction */
  sFLASH_SendByte(sFLASH_CMD_RDSR);


  /*!< Loop as long as the memory is busy with a write cycle */
  do
  {
    /*!< Send a dummy byte to generate the clock needed by the FLASH
    and put the value of the status register in FLASH_Status variable */
    flashstatus = sFLASH_SendByte(sFLASH_DUMMY_BYTE);


  }
  while ((flashstatus & sFLASH_WIP_FLAG) == SET); /* Write in progress */


  /*!< Deselect the FLASH: Chip Select high */
  sFLASH_CS_HIGH();
}


/**
  * @brief  Initializes the peripherals used by the SPI FLASH driver.
  * @param  None
  * @retval None
  */
void sFLASH_LowLevel_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;


  /*!< Enable the SPI clock */
  sFLASH_SPI_CLK_INIT(sFLASH_SPI_CLK, ENABLE);


  /*!< Enable GPIO clocks */
  RCC_AHB1PeriphClockCmd(sFLASH_SPI_SCK_GPIO_CLK | sFLASH_SPI_MISO_GPIO_CLK | 
                         sFLASH_SPI_MOSI_GPIO_CLK | sFLASH_CS_GPIO_CLK, ENABLE);
  
  /*!< SPI pins configuration *************************************************/


  /*!< Connect SPI pins to AF5 */  
  GPIO_PinAFConfig(sFLASH_SPI_SCK_GPIO_PORT, sFLASH_SPI_SCK_SOURCE, sFLASH_SPI_SCK_AF);
  GPIO_PinAFConfig(sFLASH_SPI_MISO_GPIO_PORT, sFLASH_SPI_MISO_SOURCE, sFLASH_SPI_MISO_AF);
  GPIO_PinAFConfig(sFLASH_SPI_MOSI_GPIO_PORT, sFLASH_SPI_MOSI_SOURCE, sFLASH_SPI_MOSI_AF);


  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_DOWN;
        
  /*!< SPI SCK pin configuration */
  GPIO_InitStructure.GPIO_Pin = sFLASH_SPI_SCK_PIN;
  GPIO_Init(sFLASH_SPI_SCK_GPIO_PORT, &GPIO_InitStructure);


  /*!< SPI MOSI pin configuration */
  GPIO_InitStructure.GPIO_Pin =  sFLASH_SPI_MOSI_PIN;
  GPIO_Init(sFLASH_SPI_MOSI_GPIO_PORT, &GPIO_InitStructure);


  /*!< SPI MISO pin configuration */
  GPIO_InitStructure.GPIO_Pin =  sFLASH_SPI_MISO_PIN;
  GPIO_Init(sFLASH_SPI_MISO_GPIO_PORT, &GPIO_InitStructure);


  /*!< Configure sFLASH Card CS pin in output pushpull mode ********************/
  GPIO_InitStructure.GPIO_Pin = sFLASH_CS_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(sFLASH_CS_GPIO_PORT, &GPIO_InitStructure);
}


/**
  * @brief  DeInitializes the peripherals used by the SPI FLASH driver.
  * @param  None
  * @retval None
  */
void sFLASH_LowLevel_DeInit(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;


  /*!< Disable the sFLASH_SPI  ************************************************/
  SPI_Cmd(sFLASH_SPI, DISABLE);
  
  /*!< DeInitializes the sFLASH_SPI *******************************************/
  SPI_I2S_DeInit(sFLASH_SPI);
  
  /*!< sFLASH_SPI Periph clock disable ****************************************/
  sFLASH_SPI_CLK_INIT(sFLASH_SPI_CLK, DISABLE);
      
  /*!< Configure all pins used by the SPI as input floating *******************/
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;


  GPIO_InitStructure.GPIO_Pin = sFLASH_SPI_SCK_PIN;
  GPIO_Init(sFLASH_SPI_SCK_GPIO_PORT, &GPIO_InitStructure);


  GPIO_InitStructure.GPIO_Pin = sFLASH_SPI_MISO_PIN;
  GPIO_Init(sFLASH_SPI_MISO_GPIO_PORT, &GPIO_InitStructure);


  GPIO_InitStructure.GPIO_Pin = sFLASH_SPI_MOSI_PIN;
  GPIO_Init(sFLASH_SPI_MOSI_GPIO_PORT, &GPIO_InitStructure);


  GPIO_InitStructure.GPIO_Pin = sFLASH_CS_PIN;
  GPIO_Init(sFLASH_CS_GPIO_PORT, &GPIO_InitStructure);
}