spi四种工作模式时序图 spi通信时序图详解

?SPI(Serial peripheral interface)即串行外围设备接口，是由Motorola首先在其MC68HCxx系列单片机上定义的，基于高速全双工总线的通讯协议。(又是高速，而且全双工，确实强大)被广泛应用于ADC、LCD等设备与MCU之间。
??跟前面学习I2C、USART一样，学习一种协议，还是从两个层面分析：物理层和协议层。
1. SPI物理层
SPI通讯需要使用4条线：3条总线和1条片选

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图6
更正：工作模式3的CPOL应为1 。
【spi四种工作模式时序图 spi通信时序图详解】注意要让主机和从机需要在相同的工作模式下，这样才可以实现正常通讯。
下面介绍用STM32库函数实SPI通讯代码。

#ifndef __SPI_H#define __SPI_H#include "stm32f10x.h"/* ?¨ò?è???±?á? */void SPI2_Config(void);void SPI2_SetSpeed(uint8_t Speed);uint8_t SPI2_WriteReadData(uint8_t dat);void SPI1_Config(void);void SPI1_SetSpeed(uint8_t speed);uint8_t SPI1_WriteReadData(uint8_t dat);/***************************************************************************** Function Name: SPI1_Config* Description: 3?ê??ˉSPI2* Input: None* Output: None* Return: None****************************************************************************/void SPI1_Config(void){GPIO_InitTypeDef GPIO_InitStructure;SPI_InitTypeDefSPI_InitStructure;/* SPIμ?IO?úoíSPIíaéè′ò?aê±?ó */RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);/* SPIμ?IO?úéè?? */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_SetBits(GPIOA,GPIO_Pin_5|GPIO_Pin_6|GPIO_Pin_7); //PA5.6.7é?à-/***************************************************************************//************************* éè??SPIμ?2?êy ***********************************//***************************************************************************/SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;//????è???1¤SPI?￡ê?SPI_InitStructure.SPI_Mode = SPI_Mode_Master;//?÷?ú?￡ê?SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b; //8??SPISPI_InitStructure.SPI_CPOL = SPI_CPOL_High;//ê±?óDü????μ???SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;//?úμú?t??ê±?ó2é?ˉêy?YSPI_InitStructure.SPI_NSS = SPI_NSS_Soft;//Nssê1ó?èí?t????/* ????2¨ì??ê?¤·??μ?a256 */SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;//′ó×??????aê?′?ê?SPI_InitStructure.SPI_CRCPolynomial = 7;SPI_Cmd(SPI1, ENABLE);SPI_Init(SPI1, &SPI_InitStructure);}/***************************************************************************** Function Name: SPI2_Config* Description: 3?ê??ˉSPI2* Input: None* Output: None* Return: None****************************************************************************/void SPI2_Config(void){GPIO_InitTypeDef GPIO_InitStructure;SPI_InitTypeDefSPI_InitStructure;/* SPIμ?IO?úoíSPIíaéè′ò?aê±?ó */RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);/* SPIμ?IO?úéè?? */GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOB, &GPIO_InitStructure);/***************************************************************************//************************* éè??SPIμ?2?êy ***********************************//***************************************************************************/SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;//????è???1¤SPI?￡ê?SPI_InitStructure.SPI_Mode = SPI_Mode_Master;//?÷?ú?￡ê?SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b; //8??SPISPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;//ê±?óDü????μ???SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;//?úμú?t??ê±?ó2é?ˉêy?YSPI_InitStructure.SPI_NSS = SPI_NSS_Soft;//Nssê1ó?èí?t????/* ????2¨ì??ê?¤·??μ?a256 */SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256;SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;//′ó×??????aê?′?ê?SPI_InitStructure.SPI_CRCPolynomial = 7;SPI_Cmd(SPI2, ENABLE);SPI_Init(SPI2, &SPI_InitStructure);}/***************************************************************************** Function Name: SPI1_SetSpeed* Description: éè??SPI1μ?′?ê??ù?è?￡* Input: ?ù?è2¨ì??ê·??μ* Output: None* Return: None****************************************************************************/void SPI1_SetSpeed(uint8_t speed){SPI1->CR1 &= 0xFFC7; SPI1->CR1 |= speed;SPI_Cmd(SPI1, ENABLE);}/***************************************************************************** Function Name: SPI2_SetSpeed* Description: éè??SPI2μ?·??μêy￡?ò???±?SPI2μ??ù?è.* Input: Speed￡o·??μêy* Output: None* Return: None****************************************************************************/void SPI2_SetSpeed(uint8_t Speed){SPI2->CR1 &= 0xFFC7; SPI2->CR1 |= Speed;SPI_Cmd(SPI2,ENABLE); }/***************************************************************************** Function Name: SPI1_WriteReadData* Description: ê1ó?SPI1D′è?ò???×??úêy?Yí?ê±?áè?ò???×??úêy?Y?￡* Input: dat￡oòaD′μ?8??êy?Y* Output: None* Return: ?áè?μ?μ?8??êy?Y****************************************************************************/uint8_t SPI1_WriteReadData(uint8_t dat){uint16_t i = 0;/* μ±·￠?í?o3??÷?? */ while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET){i++;if(i > 10000){return 0xFF;}}/* ·￠?íêy?Y */SPI_I2S_SendData(SPI1, dat);/* μè′y?óê??o3??÷?a·??? */while(SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET); /* ???áè?μ?μ?êy?μ·μ?? */ return SPI_I2S_ReceiveData(SPI1);}/***************************************************************************** Function Name: SPI2_WriteReadData* Description: ê1ó?SPI2D′è?ò???×??úêy?Yí?ê±?áè?ò???×??úêy?Y?￡* Input: dat￡oD′è?μ?êy?Y* Output: None* Return: ?áè?μ?μ?êy?Y** ?áè?ê§°ü·μ??0xFF****************************************************************************/uint8_t SPI2_WriteReadData(uint8_t dat){uint16_t i = 0;/* μ±·￠?í?o3??÷?? */ while(SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_TXE) == RESET){i++;if(i > 10000){return 0xFF;}}/* ·￠?íêy?Y */SPI_I2S_SendData(SPI2, dat);/* μè′y?óê??o3??÷?a·??? */while(SPI_I2S_GetFlagStatus(SPI2, SPI_I2S_FLAG_RXNE) == RESET); /* ???áè?μ?μ?êy?μ·μ?? */ return SPI_I2S_ReceiveData(SPI2);}