example_281xsci_autobaud.c

对 TI DSP TMSP320F2812 串口进行操作的源程序

//###########################################################################
//
// FILE:	Example_281xSci_Autobaud_.c
//
// TITLE:	DSP281x SCI Autobaud detect example 
//
// ASSUMPTIONS:
//
//          This program requires the DSP281x V1.00 header files.  
//          As supplied, this project is configured for "boot to H0" operation. 
//
//          Test requires the following hardware connections:
//          
//          SCIATX <-> SCIBRX
//          SCIARX <-> SCIATX
//
//          This test will perform autobaud lock at a variety of baud rates, including
//          very high baud rates.  
//
//          For this test to properly run, connect the SCI-A pins to the 
//          SCI-B pins without going through a transciever.  
// 
//          At higher baud rates, the slew rate of the incoming data bits can be 
//          affected by transceiver and connector performance. This slew rate may
//          limit reliable autobaud detection at higher baud rates.  
//          
//          SCIA: Slave, autobaud locks, receives characters and
//                echos them back to the host.  Uses the RX interrupt
//                to receive characters.
//
//          SCIB: Host, known baud rate, sends characters to the slave
//                and checks that they are echoed back.
//
// DESCRIPTION:
//
//          Internal Loopback test for ever through SCIA using interrupts,
//	        FIFOs are disabled. 
//
//          Watch Variables: BRRVal - current BRR value used for SCIB
//                           ReceivedAChar - character received by SCIA
//                           ReceivedBChar - character received by SCIB
//                           SendChar      - character being sent by SCIB
//                           SciaRegs.SCILBAUD - SCIA baud registers - set
//                           SciaRegs.SCIHBAUD   by autobaud lock
//		
//
//###########################################################################
//
//  Ver | dd mmm yyyy | Who  | Description of changes
// =====|=============|======|===============================================
// 1.00 | 11 Sep 2003 | L.H. | First Release 
//###########################################################################


#include "DSP281x_Device.h"     // DSP281x Headerfile Include File
#include "DSP281x_Examples.h"   // DSP281x Examples Include File

#define BAUDSTEP 100            // Amount BRR will be incremented between each
                                // autobaud lock

// Prototype statements for functions found within this file.
void scia_init(void);
void scib_init(void);
void scia_xmit(int a);
void scib_xmit(int a);
void scia_AutobaudLock(void);
void error(int);
interrupt void rxaint_isr(void); 


// Global counts used in this example
Uint16 LoopCount;
//Uint16 xmitCount;
Uint16 ReceivedCount;
Uint16 ErrorCount; 
Uint16 SendChar;
Uint16 ReceivedAChar;   // scia received character
Uint16 ReceivedBChar;   // scib received character
Uint16 BRRVal;
Uint16 Buff[10] = {0x55, 0xAA, 0xF0, 0x0F, 0x00, 0xFF, 0xF5, 0x5F, 0xA5, 0x5A};

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  

   EALLOW;
   GpioMuxRegs.GPFMUX.all=0x0030;	// Select GPIOs to be Scia pins	 
                                    // Port F MUX - x000 0000 0011 0000
   GpioMuxRegs.GPGMUX.all=0x0030;	// Select GPIOs to be Scib pins	 
                                    // Port G MUX - x000 0000 0011 0000
   EDIS;

// 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 DSP281x_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 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.RXAINT = &rxaint_isr;
   EDIS;       // This is needed to disable write to EALLOW protected register

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP281x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
   scia_init();       // Initalize SCIA
   scib_init();       // Initalize SCIB

// Step 5. User specific code, enable interrupts:
	
   LoopCount = 0;
   ErrorCount = 0;
    
// Enable interrupts
   PieCtrlRegs.PIEIER9.all = 0x0001; // Enable all SCIA RXINT interrupt
   IER |= 0x0100;			         // enable PIEIER9, and INT9
   EINT;
    
    // Start with BRR = 1, work through each baud rate setting
    // incrementing BRR by BAUDSTEP
    for (BRRVal = 0x0000; BRRVal < (Uint32)0xFFFF; BRRVal+=BAUDSTEP)
    {
          
        // SCIB has a known baud rate.  SCIA will autobaud to match  
	    ScibRegs.SCIHBAUD = (BRRVal >> 8);
	    ScibRegs.SCILBAUD = (BRRVal);    
	    
	    // Initiate an autobaud lock with scia.  Check
	    // returned character against baud lock character 'A' 
	    scia_AutobaudLock();
	    while(ScibRegs.SCIRXST.bit.RXRDY != 1) { } 
	    ReceivedBChar = 0;
	    ReceivedBChar =  ScibRegs.SCIRXBUF.bit.RXDT;
	    if(ReceivedBChar != 'A') 
	    {
	        error(0);
	    }
    
	    // Send/echoback characters
	    // 55 AA F0 0F 00 FF F5 5F A5 5A 
	    for(i= 0; i<=9; i++) 
	    {
	      SendChar = Buff[i];
	      scib_xmit(SendChar);			    // Initiate interrupts and xmit data in isr
	      // Wait to get the character back and check
	      // against the sent character.
	      while(ScibRegs.SCIRXST.bit.RXRDY != 1) 
	      { 
	          asm("   NOP");
	      } 
	      ReceivedBChar = 0;
	      ReceivedBChar =  ScibRegs.SCIRXBUF.bit.RXDT;
	      if(ReceivedBChar != SendChar) error(1);
	    }
    
    } // Repeat for next BRR setting 
    
    // Stop here, no more
    for(;;)
    {
       asm("    NOP");
    }


} 	


/* --------------------------------------------------- */
/* ISR for PIE INT9.1                                  */
/* Connected to RXAINT  SCI-A                          */
/* ----------------------------------------------------*/
     
interrupt void rxaint_isr(void)     // SCI-A
{
  // Insert ISR Code here
   
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP9;
   
   // If we were autobaud detecting, we must clear CDC
   if(SciaRegs.SCIFFCT.bit.CDC == 1) 
   {
      SciaRegs.SCIFFCT.bit.ABDCLR = 1;
      SciaRegs.SCIFFCT.bit.CDC = 0;
      // Check received character - should be 'A'
      ReceivedAChar = 0;
      ReceivedAChar = SciaRegs.SCIRXBUF.all;
      if(ReceivedAChar != 'A') 
      {
         error(2);
      }
      else scia_xmit(ReceivedAChar);       
   }  
   
   // This was not autobaud detect
   else 
   {      
      // Check received character against sendchar
      ReceivedAChar = 0;
      ReceivedAChar = SciaRegs.SCIRXBUF.all;
      if(ReceivedAChar != SendChar) 
      {
         error(3);
      }
      else scia_xmit(ReceivedAChar);
   }
      
   SciaRegs.SCIFFRX.bit.RXFFINTCLR = 1;	// clear Receive interrupt flag  
   ReceivedCount++;
}


void error(int ErrorFlag)
{
      ErrorCount++;
      asm("     ESTOP0");  	       // Uncomment to stop the test here
      for (;;);

}

// SCIA  8-bit word, baud rate 0x000F, default, 1 STOP bit, no parity 
void scia_init()
{    
    // Note: Clocks were turned on to the SCIA peripheral
    // in the InitSysCtrl() function

    // Reset FIFO's 
    SciaRegs.SCIFFTX.all=0x8000;
        
    SciaRegs.SCICCR.all =0x0007;   // 1 stop bit,  No loopback 
                                   // No parity,8 char bits,
                                   // async mode, idle-line protocol
    SciaRegs.SCICTL1.all =0x0003;  // enable TX, RX, internal SCICLK, 
                                   // Disable RX ERR, SLEEP, TXWAKE
    SciaRegs.SCICTL2.all =0x0003; 
    SciaRegs.SCICTL2.bit.RXBKINTENA =1;
    SciaRegs.SCICTL1.all =0x0023;     // Relinquish SCI from Reset 


}

// SCIB  8-bit word, baud rate 0x000F, default, 1 STOP bit, no parity 
 
void scib_init()
{
    // Reset FIFO's 
    ScibRegs.SCIFFTX.all=0x8000;

    // 1 stop bit, No parity, 8-bit character
    // No loopback
    ScibRegs.SCICCR.all = 0x0007;
    
    // Enable TX, RX, Use internal SCICLK
    ScibRegs.SCICTL1.all = 0x0003; 

    // Disable RxErr, Sleep, TX Wake, 
    // Diable Rx Interrupt, Tx Interrupt
    ScibRegs.SCICTL2.all = 0x0000;

    // Relinquish SCI-A from reset
    ScibRegs.SCICTL1.all = 0x0023;
     
    return;
} 




// Transmit a character from the SCI-A'
void scia_xmit(int a)
{
    SciaRegs.SCITXBUF=a;
}

// Transmit a character from the SCI-B'
void scib_xmit(int a)
{
    ScibRegs.SCITXBUF=a;
}  
    

//------------------------------------------------
// Perform autobaud lock with the host. 
// Note that if autobaud never occurs 
// the program will hang in this routine as there
// is no timeout mechanism included. 
//------------------------------------------------
                                
void scia_AutobaudLock()
{
    Uint32 i;
    
    SciaRegs.SCICTL1.bit.SWRESET = 0;
    SciaRegs.SCICTL1.bit.SWRESET = 1;
    
    // Must prime baud register with >= 1
    SciaRegs.SCILBAUD = 1;
    
    // Prepare for autobaud detection
    // Make sure the ABD bit is clear by writing a 1 to ABDCLR
    // Set the CDC bit to enable autobaud detection
    SciaRegs.SCIFFCT.bit.ABDCLR = 1;
    SciaRegs.SCIFFCT.bit.CDC = 1;
    
    // Wait until we correctly read an 
    // 'A' or 'a' and lock    
    while(SciaRegs.SCIFFCT.bit.CDC == 1) 
    {
       // Note the lower the baud rate the longer
       // this delay has to be
       for(i = 1; i<= 0x0FFFFFF; i++) 
       {
          asm("     NOP");
       }  // delay
       
       if(SciaRegs.SCIFFCT.bit.CDC == 1) scib_xmit('A');
    }

    return;   
}
    


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