stm32的SPI通信问题

只看该作者 · 2014-3-31 12:19

我用STM32作为从机与DSP进行通信一致有问题，今天不连接DSP的情况下用示波器测STM的SCK引脚居然一直有脉冲，可是我明明配置为从模式了，对STM32的SPI设置如下：
void SPI_Configuration(void)
{
  SPI_InitTypeDef SPI_InitStructure;
  /* SPI1 Config -------------------------------------------------------------*/
  SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
  SPI_InitStructure.SPI_Mode = SPI_Mode_Slave;
  SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;
  SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
  SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
  SPI_InitStructure.SPI_NSS = SPI_NSS_Hard;
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_LSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(SPI1, &SPI_InitStructure);
  SPI_Cmd(SPI1, ENABLE);

}
SPI的引脚配置：
  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;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
SPI时钟使能：
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
各位请帮忙看看，究竟是什么问题呀，谢谢了