关于SPI的一点疑问

发布于 2019-11-13 14:27:01 浏览：1475 订阅该版

```
void spi_gpio_init(void)
{
	SPI_InitTypeDef  SPI_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;
  
  /* Ê¹ÄÜ FLASH_SPI ¼°GPIO Ê±ÖÓ */
  /*!< SPI_FLASH_SPI_CS_GPIO, SPI_FLASH_SPI_MOSI_GPIO, 
       SPI_FLASH_SPI_MISO_GPIO,SPI_FLASH_SPI_SCK_GPIO Ê±ÖÓÊ¹ÄÜ */
  RCC_AHB1PeriphClockCmd (FLASH_SPI_SCK_GPIO_CLK | FLASH_SPI_MISO_GPIO_CLK|FLASH_SPI_MOSI_GPIO_CLK|FLASH_CS_GPIO_CLK, ENABLE);

/*!< SPI_FLASH_SPI Ê±ÖÓÊ¹ÄÜ */
  FLASH_SPI_CLK_INIT(FLASH_SPI_CLK, ENABLE);
 
  //ÉèÖÃÒý½Å¸´ÓÃ
  GPIO_PinAFConfig(FLASH_SPI_SCK_GPIO_PORT,FLASH_SPI_SCK_PINSOURCE,FLASH_SPI_SCK_AF); 
	GPIO_PinAFConfig(FLASH_SPI_MISO_GPIO_PORT,FLASH_SPI_MISO_PINSOURCE,FLASH_SPI_MISO_AF); 
	GPIO_PinAFConfig(FLASH_SPI_MOSI_GPIO_PORT,FLASH_SPI_MOSI_PINSOURCE,FLASH_SPI_MOSI_AF); 
  
  /*!< ÅäÖÃ SPI_FLASH_SPI Òý½Å: SCK */
  GPIO_InitStructure.GPIO_Pin = FLASH_SPI_SCK_PIN;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;  
  
  GPIO_Init(FLASH_SPI_SCK_GPIO_PORT, &GPIO_InitStructure);
  
	/*!< ÅäÖÃ SPI_FLASH_SPI Òý½Å: MISO */
  GPIO_InitStructure.GPIO_Pin = FLASH_SPI_MISO_PIN;
  GPIO_Init(FLASH_SPI_MISO_GPIO_PORT, &GPIO_InitStructure);
  
	/*!< ÅäÖÃ SPI_FLASH_SPI Òý½Å: MOSI */
  GPIO_InitStructure.GPIO_Pin = FLASH_SPI_MOSI_PIN;
  GPIO_Init(FLASH_SPI_MOSI_GPIO_PORT, &GPIO_InitStructure);

/*!< ÅäÖÃ SPI_FLASH_SPI Òý½Å: CS */
  GPIO_InitStructure.GPIO_Pin = FLASH_CS_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
  GPIO_Init(FLASH_CS_GPIO_PORT, &GPIO_InitStructure);

/* Í£Ö¹ÐÅºÅ FLASH: CSÒý½Å¸ßµçÆ½*/
//  SPI_FLASH_CS_HIGH();

/* FLASH_SPI Ä£Ê½ÅäÖÃ */
  // FLASHÐ¾Æ¬ Ö§³ÖSPIÄ£Ê½0¼°Ä£Ê½3£¬¾Ý´ËÉèÖÃCPOL CPHA
  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_BaudRatePrescaler_2;
  SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
  SPI_InitStructure.SPI_CRCPolynomial = 7;
  SPI_Init(FLASH_SPI, &SPI_InitStructure);

/* Ê¹ÄÜ FLASH_SPI  */
  SPI_Cmd(FLASH_SPI, ENABLE);

/* Ê¹ SPI_FLASH ½øÈë 4 ×Ö½ÚµØÖ·Ä£Ê½ */
//	SPI_FLASH_Mode_Init();
}
//
void spiinitailize(void)
{
	
}

void cs_high(void)
{
  GPIO_SetBits(FLASH_CS_GPIO_PORT,FLASH_CS_PIN);
}

void cs_low(void)
{
  GPIO_ResetBits(FLASH_CS_GPIO_PORT,FLASH_CS_PIN);
}

void spi_send_byte(uint8 byte)
{
  while (SPI_I2S_GetFlagStatus(FLASH_SPI, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(FLASH_SPI, byte);
  while (SPI_I2S_GetFlagStatus(FLASH_SPI, SPI_I2S_FLAG_RXNE) == RESET);
  SPI_I2S_ReceiveData(FLASH_SPI);
}

uint8 spi_read_byte(void)
{
  while (SPI_I2S_GetFlagStatus(FLASH_SPI, SPI_I2S_FLAG_TXE) == RESET);
  SPI_I2S_SendData(FLASH_SPI, 0);
  while (SPI_I2S_GetFlagStatus(FLASH_SPI, SPI_I2S_FLAG_RXNE) == RESET);
  return SPI_I2S_ReceiveData(FLASH_SPI);
}
```以上是我写的SPI初始化和控制CSS片选脚高低和SPI读数据写数据的程序
[attach]12239[/attach]

![微信截图_20191113142441.png](/uploads/201911/13/142538gf0qfwwwm3f2vrf3.png)
这是我定义的两组SPI，SPI4可以正常通信，SPI3不可以正常通信，不知道是什么原因，用的是STM32F4，请大神指教。

![微信截图_20191113142416.png](https://oss-club.rt-thread.org/uploads/201911/13/142550caml8snsnjvd1an7.png)