[转]普通GPIO口模拟SPI通信协议

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：

下面是我基于ATSAM4SD16B芯片在Atmel Studio上用普通GPIO模拟的SPI通信协议的代码：

#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 mode
typedef 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 type
typedef enum SPIType
{
    SPIMaster,
    SPISlave,
}SPIType;

// Define SPI attribute
typedef 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 prototypes
void 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 pins
Spi_t Spi_0 = 
{
    .ui_CS = CS,
    .ui_SCLK = SCLK,
    .ui_MOSI = MOSI,
    .ui_MISO = MISO,
    .spiMode = Mode_1,
    .spiType = SPIMaster,
};

/*
Brief: SPI protocol initiate
Input: p_Spi, which spi use
Output: None
Return: None
Author: 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 disable 

Input: (1)p_Spi, which spi use 

       (2)i_IsEnable, Chip select(Slave select) enable flag 

Output: None 

Return: None 

Author: 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 data 

Input: (1)p_Spi, which spi use 

       (2)uc_Bt, write byte data 

Output: None 

Return: None 

Author: 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 data 

Input: (1)p_Spi, which spi use 

       (2)puc_Data, write data string 

       (3)i_DataLength, write data length 

Output: None 

Return: None 

Author: 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 SPI 

Input: p_Spi, which spi use 

Output: None 

Return: Read data 

Author: 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 data 

Input: (1)p_Spi, which SPI use; 

       (2)i_DataLength, the length of data that need to read 

Output: puc_Data, need to get data 

Return: None 

Author: 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);


}