TMS320F28377D: 使用28377d（作为主机）的spi通信接口与其他芯片开发板进行通信，无FIFO模式，在禁用loopback模式后，TXBUF依然和RXBUF的值保持一致，而并未接收到从机的返回数据

unsigned char trans[6] = {0xAA,0xC3,0x00,0xA2,0x00,0x24}; //所要发送的信息
void spi_xmit(Uint16 a); //发送一个数据
void Ready_Config(); //从机芯片ready标志位，此位读到1表明从机已经准备好，才可以与从机进行通信
void SPI_RXbuff(unsigned char *buff,unsigned int len);
void SPI_TXbuff(unsigned char *buff,unsigned int len);
unsigned char cmd_result[2] = {0x00}; //所要接收的返回信息存放数组，目前为0

void main(void)
{
    Ready_Config();

//TI官方spi loopback例程，给出的初始化
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the F2837xS_SysCtrl.c file.
   InitSysCtrl();

// Step 2. Initialize GPIO:
// This example function is found in the F2837xS_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
   InitGpio();  // Skipped for this example
// Setup only the GP I/O only for SPI-A functionality
// This function is found in F2837xS_Spi.c
   InitSpiaGpio();

// Step 3. Clear all __interrupts and initialize PIE vector table:
// Disable CPU __interrupts
   DINT;

// Initialize PIE control registers to their default state.
// The default state is all PIE __interrupts disabled and flags
// are cleared.
// This function is found in the F2837xS_PieCtrl.c file.
   InitPieCtrl();

// Disable CPU __interrupts and clear all CPU __interrupt flags:
   IER = 0x0000;
   IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the __interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in F2837xS_DefaultIsr.c.
// This function is found in F2837xS_PieVect.c.
   InitPieVectTable();

// Step 4. Initialize the Device Peripherals:
   InitSpi();        // init SPI
//发送接收
   SPI_TXbuff(trans,6);
   DELAY_US(10);
  SPI_RXbuff(cmd_result,2);
}

//各函数定义
void spi_xmit(Uint16 a)
{
    //while(SpiaRegs.SPISTS.bit.BUFFULL_FLAG);
    SpiaRegs.SPITXBUF=a;    // SPI Serial Output Buffer Register
    //while(SpiaRegs.SPISTS.bit.INT_FLAG != 1);
}

//Ready信号接收引脚设置为GPIO10
void Ready_Config()
{
     EALLOW;
     GpioCtrlRegs.GPAMUX1.bit.GPIO10 = 0; //i/o
    // GpioCtrlRegs.GPAPUD.bit.GPIO10 = 0; //内部上拉
     GpioCtrlRegs.GPADIR.bit.GPIO10 = 0; //input
     EDIS;
}


//接收缓冲区数据函数
void SPI_RXbuff(unsigned char *buff,unsigned int len)  //uint8_t uint32_t
{
    unsigned int i = 0;
    if(len==0)  return;
    while(GpioDataRegs.GPADAT.bit.GPIO10 == 0);//等待从机就绪
    GpioDataRegs.GPACLEAR.bit.GPIO11 = 1; //拉低片选信号
    DELAY_US(10);
    for(i=0;i<len;i++)
    {
         buff[i] = (SpiaRegs.SPIRXBUF>>8);
         DELAY_US(10);
     }
    GpioDataRegs.GPASET.bit.GPIO11 = 1;//拉高片选信号
}

//发送缓冲区数据函数
void SPI_TXbuff(unsigned char *buff,unsigned int len)  //uint8_t uint32_t
{
    unsigned int i = 0;
    if(len==0)  return;
    while(GpioDataRegs.GPADAT.bit.GPIO10 == 0);//等待从机就绪
    GpioDataRegs.GPACLEAR.bit.GPIO11 = 1; //拉低片选信号
    DELAY_US(10);
    for(i=0;i<len;i++)
    {
        spi_xmit(buff[i]);  //左移8位，适应MSB的要求
        DELAY_US(10);
     }
    GpioDataRegs.GPASET.bit.GPIO11 = 1;//拉高片选信号
}


//spi.c文件里spi配置
#include "F2837xD_device.h"
#include "F2837xD_Examples.h"

//
// Calculate BRR: 7-bit baud rate register value
// SPI CLK freq = 115200 Hz
// LSPCLK freq  = CPU freq / 4  (by default)
// BRR          = (LSPCLK freq / SPI CLK freq) - 1
//
#if CPU_FRQ_200MHZ
#define SPI_BRR        ((200E6 / 4) / 115200) - 1
#endif

#if CPU_FRQ_150MHZ
#define SPI_BRR        ((150E6 / 4) / 115200) - 1
#endif

#if CPU_FRQ_120MHZ
#define SPI_BRR        ((120E6 / 4) / 115200) - 1
#endif

//
// InitSPI - This function initializes the SPI to a known state
//
void InitSpi(void)
{
    // Initialize SPI-A

    // Set reset low before configuration changes
    // Clock polarity (0 == rising, 1 == falling)
    // 8-bit character
    // disable loop-back
    SpiaRegs.SPICCR.bit.SPISWRESET = 0;
    SpiaRegs.SPICCR.bit.CLKPOLARITY = 0;
    SpiaRegs.SPICCR.bit.SPICHAR = (8-1);
    SpiaRegs.SPICCR.bit.SPILBK = 0;

    // Enable master (0 == slave, 1 == master)
    // Enable transmission (Talk)
    // Clock phase (0 == normal, 1 == delayed)
    // SPI interrupts are  disabled
    SpiaRegs.SPICTL.bit.MASTER_SLAVE = 1;
    SpiaRegs.SPICTL.bit.TALK = 1;
    SpiaRegs.SPICTL.bit.CLK_PHASE = 0;
    SpiaRegs.SPICTL.bit.SPIINTENA = 0;

    // Set the baud rate
    SpiaRegs.SPIBRR.bit.SPI_BIT_RATE = SPI_BRR;

    // Set FREE bit
    // Halting on a breakpoint will not halt the SPI
    SpiaRegs.SPIPRI.bit.FREE = 1;

    // Release the SPI from reset
    SpiaRegs.SPICCR.bit.SPISWRESET = 1;
}

//
// InitSpiGpio - This function initializes GPIO pins to function as SPI pins.
//               Each GPIO pin can be configured as a GPIO pin or up to 3
//               different peripheral functional pins. By default all pins come
//               up as GPIO inputs after reset.
//
//               Caution:
//               For each SPI peripheral
//               Only one GPIO pin should be enabled for SPISOMO operation.
//               Only one GPIO pin should be enabled for SPISOMI operation.
//               Only one GPIO pin should be enabled for SPICLK  operation.
//               Only one GPIO pin should be enabled for SPISTE  operation.
//               Comment out other unwanted lines.
//
void InitSpiGpio()
{
   InitSpiaGpio();
}

//
// InitSpiaGpio - Initialize SPIA GPIOs
//
void InitSpiaGpio()
{
   EALLOW;

    //
    // Enable internal pull-up for the selected pins
    //
    // Pull-ups can be enabled or disabled by the user.
    // This will enable the pullups for the specified pins.
    // Comment out other unwanted lines.
    //
    GpioCtrlRegs.GPAPUD.bit.GPIO16 = 0;  // Enable pull-up on GPIO16 (SPISIMOA)
//  GpioCtrlRegs.GPAPUD.bit.GPIO5 = 0;   // Enable pull-up on GPIO5 (SPISIMOA)
    GpioCtrlRegs.GPAPUD.bit.GPIO17 = 0;  // Enable pull-up on GPIO17 (SPISOMIA)
//  GpioCtrlRegs.GPAPUD.bit.GPIO3 = 0;   // Enable pull-up on GPIO3 (SPISOMIA)
    GpioCtrlRegs.GPAPUD.bit.GPIO18 = 0;  // Enable pull-up on GPIO18 (SPICLKA)
    GpioCtrlRegs.GPAPUD.bit.GPIO19 = 0;  // Enable pull-up on GPIO19 (SPISTEA)

    //
    // Set qualification for selected pins to asynch only
    //
    // This will select asynch (no qualification) for the selected pins.
    // Comment out other unwanted lines.
    //
    GpioCtrlRegs.GPAQSEL2.bit.GPIO16 = 3; // Asynch input GPIO16 (SPISIMOA)
//  GpioCtrlRegs.GPAQSEL1.bit.GPIO5 = 3;  // Asynch input GPIO5 (SPISIMOA)
    GpioCtrlRegs.GPAQSEL2.bit.GPIO17 = 3; // Asynch input GPIO17 (SPISOMIA)
//  GpioCtrlRegs.GPAQSEL1.bit.GPIO3 = 3;  // Asynch input GPIO3 (SPISOMIA)
    GpioCtrlRegs.GPAQSEL2.bit.GPIO18 = 3; // Asynch input GPIO18 (SPICLKA)
    GpioCtrlRegs.GPAQSEL2.bit.GPIO19 = 3; // Asynch input GPIO19 (SPISTEA)

    //
    //Configure SPI-A pins using GPIO regs
    //
    // This specifies which of the possible GPIO pins will be SPI functional
    // pins.
    // Comment out other unwanted lines.
    //
    GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 1; // Configure GPIO16 as SPISIMOA
//  GpioCtrlRegs.GPAMUX1.bit.GPIO5 = 2;  // Configure GPIO5 as SPISIMOA
    GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 1; // Configure GPIO17 as SPISOMIA
//  GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 2;  // Configure GPIO3 as SPISOMIA
    GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 1; // Configure GPIO18 as SPICLKA
    GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 1; // Configure GPIO19 as SPISTEA


    //使能软件片选信号 GPIO11
    GpioCtrlRegs.GPAMUX1.bit.GPIO11 = 0;  // 设置为普通的GPIO模式
    GpioCtrlRegs.GPADIR.bit.GPIO11 = 1;   //设置为输出i/o


    EDIS;
}

//
// End of file
//