ex_stwt2.c

来自「TI公司的CCS一些常用的函数库」· C语言 代码 · 共 71 行

/////////////////////////////////////////////////////////////////////////
////                           EX_STWT2.C                            ////
////                                                                 ////
////  This program uses timer 2 and interrupts to keep a             ////
////  real time seconds counter.  A simple stop watch function is    ////
////  then implemented.                                              ////
////                                                                 ////
////  Configure the CCS prototype card as described below.           ////
////                                                                 ////
////  This example will work with the PCM and PCH compilers.  The    ////
////  following conditional compilation lines are used to include a  ////
////  valid device for each compiler.  Change the device, clock and  ////
////  RS232 pins for your hardware if needed.                        ////
/////////////////////////////////////////////////////////////////////////
////        (C) Copyright 1996,2004 Custom Computer Services         ////
//// This source code may only be used by licensed users of the CCS  ////
//// C compiler.  This source code may only be distributed to other  ////
//// licensed users of the CCS C compiler.  No other use,            ////
//// reproduction or distribution is permitted without written       ////
//// permission.  Derivative programs created using this software    ////
//// in object code form are not restricted in any way.              ////
/////////////////////////////////////////////////////////////////////////


#if defined(__PCM__)
#include <16F877.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)  // Jumpers: 8 to 11, 7 to 12

#elif defined(__PCH__)
#include <18F452.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)  // Jumpers: 8 to 11, 7 to 12
#endif

#define INTS_PER_SECOND 125        // (20000000/(4*16*250*10))

int8 seconds;      // A running seconds counter
int8 int_count;    // Number of interrupts left before a second has elapsed


#INT_TIMER2                        // This function is called every time
void clock_isr() {                 // timer 2 overflows (250->0), which is
                                   // approximately 125 times per second for
    if(--int_count==0) {           // this program.
      ++seconds;
      int_count = INTS_PER_SECOND;
    }
}


void main() {
   int_count = INTS_PER_SECOND;
   setup_timer_2(T2_DIV_BY_16, 250, 10);
   set_timer2(0);
   enable_interrupts(INT_TIMER2);
   enable_interrupts(GLOBAL);

   while(TRUE) {
      printf("Press any key to begin.\n\r");
      getc();
      int_count = INTS_PER_SECOND;
      seconds = 0;
      printf("Press any key to stop.\n\r");
      getc();
      printf("%u seconds.\n\r", seconds);
   }
}