controlsuit里的样例程序spi_loopback_interrupts，请问这个程序的中断是怎么产生的。

yuan michael

程序如下所示，请问这个程序是什么时候产生中断的，怎么从main的空循环里跳出到中断服务子程序的，谢谢？

//###########################################################################
//
//!  \addtogroup f2803x_example_list
//!  <h1>SPI Digital Loop Back with Interrupts(spi_loopback_interrupts)</h1>
//!
//!  This program uses the internal loop back test mode of the peripheral.
//!  Other then boot mode pin configuration, no other hardware configuration
//!  is required. Both interrupts and the SPI FIFOs are used.
//!
//!  A stream of data is sent and then compared to the received stream.
//!  The sent data looks like this: \n
//!  0000 0001 \n
//!  0001 0002 \n
//!  0002 0003 \n
//!  .... \n
//!  FFFE FFFF \n
//!  FFFF 0000 \n
//!  etc.. \n
//!  This pattern is repeated forever.
//!
//!  \b Watch \b Variables \n 
//!  - \b sdata , Data to send
//!  - \b rdata , Received data
//!  - \b rdata_point , Used to keep track of the last position in
//!    the receive stream for error checking
//
//###########################################################################
// $TI Release: F2803x C/C++ Header Files and Peripheral Examples V127 $
// $Release Date: March 30, 2013 $
//###########################################################################

#include "DSP28x_Project.h"     // Device Headerfile and 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[2];     // Send data buffer
Uint16 rdata[2];     // 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 DSP2803x_SysCtrl.c file.
   InitSysCtrl();

// Step 2. Initalize GPIO:
// This example function is found in the DSP2803x_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
   InitSpiaGpio();

// 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 DSP2803x_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 DSP2803x_DefaultIsr.c.
// This function is found in DSP2803x_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 DSP2803x_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<2; i++)
   {
      sdata[i] = i;
   }
   rdata_point = 0;

// Enable interrupts required for this example
   PieCtrlRegs.PIECTRL.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.***.bit.SPISWRESET=0; // Reset SPI

   SpiaRegs.***.all=0x001F;       //16-bit character, Loopback mode
   SpiaRegs.***.all=0x0017;       //Interrupt enabled, Master/Slave XMIT enabled
   SpiaRegs.SPISTS.all=0x0000;
   SpiaRegs.SPIBRR=0x0063;           // Baud rate
   SpiaRegs.SPIFFTX.all=0xC022;      // Enable FIFO's, set TX FIFO level to 2 1100 0000 0010 0010
   SpiaRegs.SPIFFRX.all=0x0022;      // Set RX FIFO level to 2
   SpiaRegs.SPIFFCT.all=0x00;
   SpiaRegs.SPIPRI.all=0x0010;

   SpiaRegs.***.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<2;i++)
    {
       SpiaRegs.SPITXBUF=sdata[i];      // Send data
    }

//
// Increment data buffer contents by 1 for 
// the next transmit cycle
//
    for(i=0;i<2;i++)                    
    {
        sdata[i] = sdata[i] + 1;
    }

    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<2;i++)
    {
        rdata[i]=SpiaRegs.SPIRXBUF;     // Read data
    }
    for(i=0;i<2;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.
//===========================================================================

11 年多前