LPC1752读取FM25L04B的原理与实现

1. LPC1752通过SPI与FM25L04B进行通讯。
   
   图 1 LPC1752 与 FM25L04B 硬件连线图

2. 初始化LPC1752的SSP0模块
   按着如下步骤进行初始化的操作：

   • 在PCONP寄存器置位PCSSP0，允许SSP0模块的电源输出；
   • 在PCLK_SSP1寄存器中选择PCLK_SEL0，设置SSP0的时钟为CCLK/4；对SSP0的时钟进行分频，设置为CCLK/4/10；
   • 对LPC1752的管脚进行设置；
   • 设置 SPI 为主模式， FM25L04 工作在 SPI 模式 0。

   初始化代码：

void LPC17xx_SPI_Init(void)
{
    volatile uint32_t dummy;

    dummy = dummy;                                   /* avoid warning */

  LPC_SC->PCONP |= (1 << 21);                      /* Enable power to SSPI0 block */

    /* PCLK_SSP0=CCLK */
    LPC_SC->PCLKSEL1 &= ~(3<<10);                    /* PCLKSP0 = CCLK/4 (25MHz) */
    LPC_SC->PCLKSEL1 |=  (1<<10);                    /* PCLKSP0 = CCLK   (100MHz) */    

    LPC17xx_SPI_SetSpeed (SPI_SPEED_10MHz);

  LPC_GPIO0->FIODIR |=  (1<<16);                   /* P0.16 CS is output */

    /* P0.15 SCK, P0.17 MISO, P0.18 MOSI are SSP pins. */
    LPC_PINCON->PINSEL0 &= ~( (2UL<<30) );                  /* P0.15  cleared */
    LPC_PINCON->PINSEL1 &= ~( (2<<2) | (2<<4) );     /* P0.17, P0.18  cleared */
    LPC_PINCON->PINSEL0 |=  ( (2UL<<30) );           /* P0.15 SCK0 */
    LPC_PINCON->PINSEL1 |=  ( (2<<2) | (2<<4) );     /* P0.17 MISO0   P0.18 MOSI0 */

    LPC_SSP0->CR0  = ( 7<<0 );                       /* 8Bit, CPOL=0, CPHA=0         */
    LPC_SSP0->CR1  = ( 1<<1 );                       /* SSP0 enable, master          */

    /* wait for busy gone */
    while( LPC_SSP0->SR & ( 1 << SSPSR_BSY ) );

    /* drain SPI RX FIFO */
    while( LPC_SSP0->SR & ( 1 << SSPSR_RNE ) )
    {
        dummy = LPC_SSP0->DR;
    }
}

1. 读取FM25L04B
   
   FM25L04B的读时序

uint8_t FM25L04B_Read(uint32_t Dst, uint8_t* RcvBufPt, uint32_t NByte)
{
    uint8_t addr_a8;    
    uint32_t i = 0;
//  if ((Dst+NByte > MAX_ADDR)||(NByte == 0))   return (ERROR); 
    addr_a8 = (Dst & 0xffffff00)>>5;

    SPI_FLASH_WP_UNLOCK();
  SPI_FLASH_CS_LOW();
    FM25L04B_ReadWriteByte(READ_CMD|addr_a8);
    FM25L04B_ReadWriteByte(Dst & 0x00ff);                   
    for (i = 0; i < NByte; i++)     
    {
       RcvBufPt[i] = FM25L04B_ReadWriteByte(0xFF);      
    }
  SPI_FLASH_CS_HIGH();
    SPI_FLASH_WP_LOCK();

    return 0;
}

1. 写FM25L04B
   
   FM25L04B的写时序

uint8_t FM25L04B_Write(uint32_t Dst, uint8_t* SndbufPt,uint32_t NByte)
{
    uint8_t addr_a8;    
    uint8_t temp = 0,StatRgVal = 0;
    uint32_t i = 0; 

//  if (( (Dst+NByte-1 > MAX_ADDR)||(NByte == 0) ))
//  {
//      return (ERROR);  /* ?????? */
//  }

    addr_a8 = (Dst & 0xffffff00)>>5;

    SPI_FLASH_WP_UNLOCK();
    SPI_FLASH_CS_LOW();              
    FM25L04B_ReadWriteByte(RDSR_CMD);                              
    temp = FM25L04B_ReadWriteByte(0xFF);                       
    SPI_FLASH_CS_HIGH();

    for(i = 0; i < NByte; i++)
    {   
        SPI_FLASH_CS_LOW();     
        FM25L04B_ReadWriteByte(WREN_CMD);   
        SPI_FLASH_CS_HIGH();    

        SPI_FLASH_CS_LOW();                 
        FM25L04B_ReadWriteByte(WRITE_CMD|addr_a8);                     
      FM25L04B_ReadWriteByte((Dst+i)& 0x00ff);  
        FM25L04B_ReadWriteByte(SndbufPt[i]);                
        SPI_FLASH_CS_HIGH();            

        do
        {
          SPI_FLASH_CS_LOW();                    
            FM25L04B_ReadWriteByte(RDSR_CMD);                      
            StatRgVal = FM25L04B_ReadWriteByte(0xFF);           
            SPI_FLASH_CS_HIGH();                            
        }
        while (StatRgVal == 0x03 );                          

    }

    SPI_FLASH_CS_LOW();              
    FM25L04B_ReadWriteByte(WREN_CMD);                                              
    SPI_FLASH_CS_HIGH();            

    SPI_FLASH_CS_LOW();             
    FM25L04B_ReadWriteByte(WRSR_CMD);                             
    FM25L04B_ReadWriteByte(temp);                            
    SPI_FLASH_CS_HIGH();
    SPI_FLASH_WP_LOCK();

    return 0;
}

1. 测试代码

uint8_t Recv_buf[16];
uint8_t Send_buf[16] = {0x01,0x02,0x05,0xe4};

int main(void)
{
    SystemInit();

    LPC17xx_SPI_Init();

    FM25L04B_Read(0x0,Recv_buf, sizeof(Recv_buf));
    FM25L04B_Write(0x0,Send_buf, sizeof(Send_buf));

    memset(Recv_buf,0,sizeof(Recv_buf));
    FM25L04B_Read(0x0,Recv_buf, sizeof(Recv_buf));

    while(1) ;
}