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// File **********OC3.C***********

// Periodic Interrupt using TOC3

// Output on TC3/OC3

// Last modified 1/21/02 by Jonathan W. Valvano

 

// Copyright 2002 by Jonathan W. Valvano, valvano@uts.cc.utexas.edu 

//    You may use, edit, run or distribute this file 

//    as long as the above copyright notice remains 

unsigned short static volatile Count;

unsigned short static Period;

void (*CallBack)(void);  // call back function

#define RATE 2000  



#pragma interrupt_handler TOC3handler()

void TOC3handler(void){ // executes at 1000 Hz 

  TFLG1 = 0x08;         // acknowledge OC3

  Count++;

  TC3 = TC3+RATE;       // 1 ms

  if(Count==Period){

    Count = 0;

    (*CallBack)();      // execute call back process

  } 

}

#pragma abs_address:0xffe8

void (*OC3_vector[])() = { TOC3handler };

#pragma end_abs_address



void Start(unsigned short thePeriod, void(*fp)(void)){

  asm(" sei");      // make ritual atomic 

  Period = thePeriod;

  CallBack = fp;

  Count  = 0;

  TIOS  |= 0x08; 
0

   // activate TC3 as output compare

  DDRT  |= 0x08;    // TC3 is an output

  TSCR   = 0x80;    // activate timer

  TMSK2  = 0x32;    // clock at 2Mhz    

  TMSK1 |= 0x08;    // arm OC3

  TFLG1  = 0x08;    // initially clear C3F 

  TCTL2 |= 0x40;    // TC3 set on next interrupt

  TC3    = TCNT+50; // first interrupt right away

  asm(" cli"); 

}