stm32之spi总结1

spi操作一定要注意spi的gpio的操作，开始因为spi_nss引脚设置成了复用推挽输出，浪费了很多时间。下面是正确的spi初始化和读写函数，在战舰开发板源码基础修改的。

void SPI1_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  SPI_InitTypeDef  SPI_InitStructure;


RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE );
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1,  ENABLE );
 
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;  //SPI CS
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; 
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  GPIO_SetBits(GPIOA,GPIO_Pin_4);

  GPIO_SetBits(GPIOA,GPIO_Pin_5|GPIO_Pin_6|GPIO_Pin_7);  


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_16;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI1, &SPI_InitStructure); 
 
SPI_Cmd(SPI1, ENABLE); //ʹÄÜSPIÍâÉè

SPI1_ReadWriteByte(0xff);//Æô¶¯´«Êä 


}   
//SPI ËÙ¶ÈÉèÖú¯Êý
//SpeedSet:
//SPI_BaudRatePrescaler_2   2·ÖƵ   
//SPI_BaudRatePrescaler_8   8·ÖƵ   
//SPI_BaudRatePrescaler_16  16·ÖƵ  
//SPI_BaudRatePrescaler_256 256·ÖƵ 
  
void SPI1_SetSpeed(u8 SpeedSet)
{
SPI1->CR1&=0XFFC7; 
SPI1->CR1|=SpeedSet;
SPI_Cmd(SPI1,ENABLE); 
} 


u8 SPI1_ReadWriteByte(u8 TxData)
{
u8 retry=0;
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET) //¼ì²éÖ¸¶¨µÄSPI±ê־λÉèÖÃÓë·ñ:·¢ËÍ»º´æ¿Õ±ê־λ
{
retry++;
if(retry>200)return 0;
}  
SPI_I2S_SendData(SPI1, TxData); //ͨ¹ýÍâÉèSPIx·¢ËÍÒ»¸öÊý¾Ý
retry=0;


while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET) //¼ì²éÖ¸¶¨µÄSPI±ê־λÉèÖÃÓë·ñ:½ÓÊÜ»º´æ·Ç¿Õ±ê־λ
{
retry++;
if(retry>200)return 0;
}     
return SPI_I2S_ReceiveData(SPI1); //·µ»Øͨ¹ýSPIx×î½ü½ÓÊÕµÄÊý¾Ý   
}