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在工作中偶尔会遇到SPI不够用的情况，而我们又要去使用SPI通信协议，此时就需要我们自己去模拟SPI通信协议。我们知道SPI通信协议有四种模式，它们分别如下所示：

#include "ioport.h"#include "pio.h"#include "delay.h"#include "SAM4S_FSA.h"#include 
   
    // Define 4 SPI pins#define CS       IOPORT_CREATE_PIN(PIOA, 8)#define SCLK     IOPORT_CREATE_PIN(PIOA, 7)#define MOSI     IOPORT_CREATE_PIN(PIOA, 23)#define MISO     IOPORT_CREATE_PIN(PIOA, 20)#define SPIDelay  delay_us(1)// Define SPI communication modetypedef enum SPIMode{    Mode_1,   /* Clock Polarity is 0 and Clock Phase is 0 */    Mode_2,   /* Clock Polarity is 0 and Clock Phase is 1 */    Mode_3,   /* Clock Polarity is 1 and Clock Phase is 0 */    Mode_4,   /* Clock Polarity is 1 and Clock Phase is 1 */}SPIMode;// Define SPI typetypedef enum SPIType{    SPIMaster,    SPISlave,}SPIType;// Define SPI attributetypedef struct SpiStruct{    unsigned int ui_CS;    unsigned int ui_SCLK;    unsigned int ui_MOSI;    unsigned int ui_MISO;    SPIMode spiMode;    SPIType spiType;}Spi_t;// Function prototypesvoid v_SPIInitSimulate(Spi_t* p_Spi);void v_CSIsEnableSimulate(Spi_t* p_Spi, int i_IsEnable);void v_SPIWriteSimulate(Spi_t* p_Spi, unsigned char* puc_Data, int i_DataLength);void v_SPIReadSimulate(Spi_t* p_Spi, unsigned char* puc_Data, int i_DataLength);// Define SPI pinsSpi_t Spi_0 = {    .ui_CS = CS,    .ui_SCLK = SCLK,    .ui_MOSI = MOSI,    .ui_MISO = MISO,    .spiMode = Mode_1,    .spiType = SPIMaster,};/*Brief: SPI protocol initiateInput: p_Spi, which spi useOutput: NoneReturn: NoneAuthor: Andy Lai*/void v_SPIInitSimulate(Spi_t* p_Spi){    assert(p_Spi != NULL);    if(p_Spi->spiMode == SPIMaster)    {        ioport_set_pin_dir(p_Spi->ui_CS, IOPORT_DIR_OUTPUT);        ioport_set_pin_dir(p_Spi->ui_SCLK, IOPORT_DIR_OUTPUT);        ioport_set_pin_dir(p_Spi->ui_MOSI, IOPORT_DIR_OUTPUT);        ioport_set_pin_dir(p_Spi->ui_MISO, IOPORT_DIR_INPUT);    }    else    {        ioport_set_pin_dir(p_Spi->ui_CS, IOPORT_DIR_INPUT);        ioport_set_pin_dir(p_Spi->ui_SCLK, IOPORT_DIR_INPUT);        ioport_set_pin_dir(p_Spi->ui_MOSI, IOPORT_DIR_INPUT);        ioport_set_pin_dir(p_Spi->ui_MISO, IOPORT_DIR_OUTPUT);    }    pio_set_pin_high(p_Spi->ui_CS);    switch(p_Spi->spiMode)    {    case Mode_1:    case Mode_2:        pio_set_pin_low(p_Spi->ui_SCLK);        break;    case Mode_3:    case Mode_4:        pio_set_pin_high(p_Spi->ui_SCLK);        break;    }}/*Brief: CS low level signal enable and high level signal disableInput: (1)p_Spi, which spi use       (2)i_IsEnable, Chip select(Slave select) enable flagOutput: NoneReturn: NoneAuthor: Andy Lai*/void v_CSIsEnableSimulate(Spi_t* p_Spi, int i_IsEnable){    assert(p_Spi != NULL);    if(i_IsEnable)    {        pio_set_pin_low(p_Spi->ui_CS);    }    else    {        pio_set_pin_high(p_Spi->ui_CS);    }}/*Brief: Use SPI to write a byte dataInput: (1)p_Spi, which spi use       (2)uc_Bt, write byte dataOutput: NoneReturn: NoneAuthor: Andy Lai*/static void v_SPIWriteByte(Spi_t* p_Spi, unsigned char uc_Bt){    int i = 0;    assert(p_Spi != NULL);    switch(p_Spi->spiMode)    {    case Mode_1: /* Clock Polarity is 0 and Clock Phase is 0 */        pio_set_pin_low(p_Spi->ui_SCLK);        for(i = 7; i >= 0; i--)        {            pio_set_pin_low(p_Spi->ui_SCLK);            SPIDelay;            pio_set_pin_high(p_Spi->ui_SCLK);            if(uc_Bt & (1 << i))            {                pio_set_pin_high(p_Spi->ui_MOSI);            }            else            {                pio_set_pin_low(p_Spi->ui_MOSI);            }            SPIDelay;        }        pio_set_pin_low(p_Spi->ui_SCLK);        break;    case Mode_2: /* Clock Polarity is 0 and Clock Phase is 1 */        pio_set_pin_low(p_Spi->ui_SCLK);        for(i = 7; i >= 0; i--)        {            pio_set_pin_high(p_Spi->ui_SCLK);            if(uc_Bt & (1 << i))            {                pio_set_pin_high(p_Spi->ui_MOSI);            }            else            {                pio_set_pin_low(p_Spi->ui_MOSI);            }            SPIDelay;            pio_set_pin_low(p_Spi->ui_SCLK);            SPIDelay;        }        pio_set_pin_low(p_Spi->ui_SCLK);        break;    case Mode_3: /* Clock Polarity is 1 and Clock Phase is 0 */        pio_set_pin_high(p_Spi->ui_SCLK);        for(i = 7; i >= 0; i--)        {            pio_set_pin_high(p_Spi->ui_SCLK);            if(uc_Bt & (1 << i))            {                pio_set_pin_high(p_Spi->ui_MOSI);            }            else            {                pio_set_pin_low(p_Spi->ui_MOSI);            }            SPIDelay;            pio_set_pin_low(p_Spi->ui_SCLK);            SPIDelay;        }        pio_set_pin_high(p_Spi->ui_SCLK);        break;    case Mode_4: /* Clock Polarity is 1 and Clock Phase is 1 */        pio_set_pin_high(p_Spi->ui_SCLK);        for(i = 7; i >= 0; i--)        {            pio_set_pin_low(p_Spi->ui_SCLK);            if(uc_Bt & (1 << i))            {                pio_set_pin_high(p_Spi->ui_MOSI);            }            else            {                pio_set_pin_low(p_Spi->ui_MOSI);            }            SPIDelay;            pio_set_pin_high(p_Spi->ui_SCLK);            SPIDelay;        }        pio_set_pin_high(p_Spi->ui_SCLK);        break;    default:        break;    }}/*Brief: Use SPI protocol to write dataInput: (1)p_Spi, which spi use       (2)puc_Data, write data string       (3)i_DataLength, write data lengthOutput: NoneReturn: NoneAuthor: Andy Lai*/void v_SPIWriteSimulate(Spi_t* p_Spi, unsigned char* puc_Data, int i_DataLength){    int i = 0;    assert(p_Spi != NULL);    assert(puc_Data != NULL);    assert(i_DataLength > 0);    v_CSIsEnableSimulate(p_Spi, 1);    delay_us(8);    // Write data    for(i = 0; i < i_DataLength; i++)    {        v_SPIWriteByte(p_Spi, puc_Data[i]);    }    delay_us(8);    v_CSIsEnableSimulate(p_Spi, 0);}/*Brief: Read a byte data from SPIInput: p_Spi, which spi useOutput: NoneReturn: Read dataAuthor: Andy Lai*/static unsigned char uc_SPIReadByte(Spi_t* p_Spi){    int i = 0;    unsigned char uc_ReadData = 0;    assert(p_Spi != NULL);    switch(p_Spi->spiMode)    {    case Mode_1: /* Clock Polarity is 0 and Clock Phase is 0 */        pio_set_pin_low(p_Spi->ui_SCLK);        for(i = 0; i < 8; i++)        {            pio_set_pin_low(p_Spi->ui_SCLK);            SPIDelay;            pio_set_pin_high(p_Spi->ui_SCLK);            uc_ReadData = uc_ReadData << 1;            uc_ReadData |= pio_get_pin_value(p_Spi->ui_MISO);            SPIDelay;        }        pio_set_pin_low(p_Spi->ui_SCLK);        break;    case Mode_2: /* Clock Polarity is 0 and Clock Phase is 1 */        pio_set_pin_low(p_Spi->ui_SCLK);        for(i = 0; i < 8; i++)        {            pio_set_pin_high(p_Spi->ui_SCLK);            SPIDelay;            pio_set_pin_low(p_Spi->ui_SCLK);            uc_ReadData = uc_ReadData << 1;            uc_ReadData |= pio_get_pin_value(p_Spi->ui_MISO);            SPIDelay;        }        pio_set_pin_low(p_Spi->ui_SCLK);        break;    case Mode_3: /* Clock Polarity is 1 and Clock Phase is 0 */        pio_set_pin_high(p_Spi->ui_SCLK);        for(i = 0; i < 8; i++)        {            pio_set_pin_high(p_Spi->ui_SCLK);            SPIDelay;            pio_set_pin_low(p_Spi->ui_SCLK);            uc_ReadData = uc_ReadData << 1;            uc_ReadData |= pio_get_pin_value(p_Spi->ui_MISO);            SPIDelay;        }        pio_set_pin_high(p_Spi->ui_SCLK);        break;    case Mode_4:  /* Clock Polarity is 1 and Clock Phase is 1 */        pio_set_pin_high(p_Spi->ui_SCLK);        for(i = 0; i < 8; i++)        {            pio_set_pin_low(p_Spi->ui_SCLK);            SPIDelay;            pio_set_pin_high(p_Spi->ui_SCLK);            uc_ReadData = uc_ReadData << 1;            uc_ReadData |= pio_get_pin_value(p_Spi->ui_MISO);            SPIDelay;        }        pio_set_pin_high(p_Spi->ui_SCLK);        break;    default:        break;    }    return uc_ReadData;}/*Brief: Use SPI to read dataInput: (1)p_Spi, which SPI use;           (2)i_DataLength, the length of data that need to readOutput: puc_Data, need to get dataReturn: NoneAuthor: Andy Lai*/void v_SPIReadSimulate(Spi_t* p_Spi, unsigned char* puc_Data, int i_DataLength){    int i = 0;    assert(p_Spi != NULL);    assert(i_DataLength > 0);    v_CSIsEnableSimulate(p_Spi, 1);    delay_us(8);    // Read data    for(i = 0; i < i_DataLength; i++)    {        puc_Data[i] = uc_SPIReadByte(p_Spi);    }    delay_us(8);    v_CSIsEnableSimulate(p_Spi, 0);}
   

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