用的是TI的SPI loop-back的例程，设置了SPICCR.SPILBK=0；但每次发送结束后，SPIRXBUF还是与SPITXBUF一样，求助？
程序如下：
#include "DSP28x_Project.h" // Device Headerfile and Examples Include File
// Prototype statements for functions found within this file.
// interrupt void ISRTimer2(void);
void delay_loop(void);
void spi_xmit(Uint16 a);
void spi_fifo_init(void);
void spi_init(void);
void error(void);
void main(void)
{
Uint16 sdata; // send data
Uint16 rdata; // received data
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();
// Step 2. Initalize GPIO:
// This example function is found in the DSP2833x_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 DSP2833x_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 DSP2833x_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 DSP2833x_DefaultIsr.c.
// This function is found in DSP2833x_PieVect.c.
InitPieVectTable();
// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2833x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
spi_fifo_init(); // Initialize the Spi FIFO
spi_init(); // init SPI
// Step 5. User specific code:
// Interrupts are not used in this example.
sdata = 0x0000;
for(;;)
{
// Transmit data
spi_xmit(sdata);
// Wait until data is received
while(SpiaRegs.SPIFFRX.bit.RXFFST !=1) { }
// Check against sent data
rdata = SpiaRegs.SPIRXBUF;
if(rdata != sdata) error();
sdata++;
}
}
// Step 7. Insert all local Interrupt Service Routines (ISRs) and functions here:
void delay_loop()
{
long i;
for (i = 0; i < 1000000; i++) {}
}
void error(void)
{
asm(" ESTOP0"); // Test failed!! Stop!
for (;;);
}
void spi_init()
{
SpiaRegs.***.all =0x000F; // Reset on, rising edge, 16-bit char bits
SpiaRegs.***.all =0x0006; // Enable master mode, normal phase,
// enable talk, and SPI int disabled.
SpiaRegs.SPIBRR =0x007F;
SpiaRegs.***.all =0x008F;
SpiaRegs.SPIPRI.bit.FREE = 1; // Set so breakpoints don't disturb xmission
}
void spi_xmit(Uint16 a)
{
SpiaRegs.SPITXBUF=a;
}
void spi_fifo_init()
{
// Initialize SPI FIFO registers
SpiaRegs.SPIFFTX.all=0xE040;
SpiaRegs.SPIFFRX.all=0x204f;
SpiaRegs.SPIFFCT.all=0x0;
}
