F2812 SPI

只看该作者 · 2013-9-17 10:33

我对TI官网上的例程“spi_loopback_interrupts”进行了测试，为什么我sdata[i]里的数据总是比rdata[i]要大3，想不明白，请教啊！程序如下

#include "DSP281x_Device.h"    // DSP281x Headerfile Include File
#include "DSP281x_Examples.h" // DSP281x Examples Include File
// Prototype statements for functions found within this file.
// interrupt void ISRTimer2(void);
interrupt void spiTxFifoIsr(void);
interrupt void spiRxFifoIsr(void);
void delay_loop(void);
void spi_fifo_init(void);
void error();
Uint16 sdata[8];    // Send data buffer
Uint16 rdata[8];    // Receive data buffer
Uint16 rdata_point;  // Keep track of where we are
                  // in the data stream to check received data
void main(void)
{
Uint16 i;
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP281x_SysCtrl.c file.
InitSysCtrl();
// Step 2. Initalize GPIO:
// This example function is found in the DSP281x_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 functionality
EALLOW;
GpioMuxRegs.GPFMUX.all=0x000F; // Select GPIOs to be SPI pins
                                 // Port F MUX - x000 0000 0000 1111
EDIS;
// Step 3. Initialize PIE vector table:
// Disable and clear all CPU interrupts
DINT;
IER = 0x0000;
IFR = 0x0000;
// Initialize PIE control registers to their default state:
// This function is found in the DSP281x_PieCtrl.c file.
InitPieCtrl();
// 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 DSP281x_DefaultIsr.c.
// This function is found in DSP281x_PieVect.c.
InitPieVectTable();
// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
EALLOW; // This is needed to write to EALLOW protected registers
PieVectTable.SPIRXINTA = &spiRxFifoIsr;
PieVectTable.SPITXINTA = &spiTxFifoIsr;
EDIS; // This is needed to disable write to EALLOW protected registers

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP281x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
spi_fifo_init(); // Initialize the SPI only

// Step 5. User specific code, enable interrupts:
// Initalize the send data buffer
for(i=0; i<8; i++)
{
   sdata[i] = i;
}
rdata_point = 0;
// Enable interrupts required for this example
PieCtrlRegs.PIECRTL.bit.ENPIE = 1; // Enable the PIE block
PieCtrlRegs.PIEIER6.bit.INTx1=1;    // Enable PIE Group 6, INT 1
PieCtrlRegs.PIEIER6.bit.INTx2=1;    // Enable PIE Group 6, INT 2
IER=0x20;                         // Enable CPU INT6
EINT;                               // Enable Global Interrupts
// Step 6. IDLE loop. Just sit and loop forever (optional):
for(;;);
}

// Some Useful local functions
void delay_loop()
{
long    i;
for (i = 0; i < 1000000; i++) {}
}
void error(void)
{
asm("    ESTOP0");  //Test failed!! Stop!
for (;;);
}

void spi_fifo_init()
{
// Initialize SPI FIFO registers
SpiaRegs.SPICCR.bit.SPISWRESET=0; // Reset SPI
SpiaRegs.SPICCR.all=0x001F;    //16-bit character, Loopback mode
SpiaRegs.SPICTL.all=0x0017;    //Interrupt enabled, Master/Slave XMIT enabled
SpiaRegs.SPISTS.all=0x0000;
SpiaRegs.SPIBRR=0x0063;          // Baud rate
SpiaRegs.SPIFFTX.all=0xC028; // Enable FIFO's, set TX FIFO level to 8
SpiaRegs.SPIFFRX.all=0x0028;    // Set RX FIFO level to 8
SpiaRegs.SPIFFCT.all=0x00;
SpiaRegs.SPIPRI.all=0x0010;
SpiaRegs.SPICCR.bit.SPISWRESET=1;  // Enable SPI
SpiaRegs.SPIFFTX.bit.TXFIFO=1;
SpiaRegs.SPIFFRX.bit.RXFIFORESET=1;
}
interrupt void spiTxFifoIsr(void)
{
  Uint16 i;
for(i=0;i<8;i++)
{
   SpiaRegs.SPITXBUF=sdata[i];    // Send data
}
for(i=0;i<8;i++)                   // Increment data for next cycle
{
   sdata[i]++;
}

SpiaRegs.SPIFFTX.bit.TXFFINTCLR=1;  // Clear Interrupt flag
PieCtrlRegs.PIEACK.all|=0x20; // Issue PIE ACK
}
interrupt void spiRxFifoIsr(void)
{
Uint16 i;
for(i=0;i<8;i++)
{
   rdata[i]=SpiaRegs.SPIRXBUF;  // Read data
}
for(i=0;i<8;i++)                   // Check received data
{
   if(rdata[i] != rdata_point+i) error();
}
rdata_point++;
SpiaRegs.SPIFFRX.bit.RXFFOVFCLR=1;  // Clear Overflow flag
SpiaRegs.SPIFFRX.bit.RXFFINTCLR=1;  // Clear Interrupt flag
PieCtrlRegs.PIEACK.all|=0x20;    // Issue PIE ack
}

//===========================================================================
// No more.
//===========================================================================