Pic C -

      EXAMPLES  


The PIC C compiler includes a library of example programs for many common applications. Each example program contains a header with instructions on how to run the example, and if necessary, the wiring instructions for interfacing external devices.

Here are three such example programs included with our compiler, as well as a list file generated by the compiler which shows the assembly generated to correspond with the C code

Jump to: Stepper Motor Controller | Seconds Timer | Simple A/D | Example List File

Stepper Motor Controller



///////////////////////////////////////////////////////////////////////
////                        EX_STEP.C                              ////
////                                                               ////
//// This program interfaces to a stepper motor.  The program will ////
//// use the RS-232 interface to either control the motor with a   ////
//// analog input, a switch input or by RS-232 command.            ////
////                                                               ////
//// Configure the CCS prototype card as follows:                  ////
////     Insert jumpers from: 11 to 17, 12 to 18                   ////
///////////////////////////////////////////////////////////////////////

#include <16C71.H>

#use Delay(Clock=20000000)

#use RS232(Baud=9600,Xmit=PIN_A3,Rcv=PIN_A2)

#byte port_b = 6

#define FOUR_PHASE TRUE

#ifdef FOUR_PHASE

byte const POSITIONS[4] = {0b0101,
                           0b1001,
                           0b1010,
                           0b0110};
#else
byte const POSITIONS[8] = {0b0101,
                           0b0001,
                           0b1001,
                           0b1000,
                           0b1010,
                           0b0010,
                           0b0110,
                           0b0100};
#endif


drive_stepper(byte speed, char dir, byte steps) {
   static byte stepper_state = 0;
   byte i;

   for(i=0;i0x80)
       drive_stepper(128-(value-128),'F',8);
  }

}


use_switch(byte speed, char dir) {

   byte steps;

   printf("\n\rSteps per press: ");
   steps = gethex();

   while(true) {
      while(input(pin_13)) ;
      drive_stepper(speed,dir,steps);
      while(!input(pin_13)) ;
      delay_ms(100);
   }
}


main() {

   byte speed,steps;
   char dir;

   setup_port_a(RA0_RA1_ANALOG);

   while (TRUE) {
       printf("\n\rSpeed (hex): ");
       speed = gethex();

       if(speed==0)
          use_pot();

       printf("\n\rDirection (F,R): ");
       dir=getc()|0x20;

       printf("\n\rSteps (hex): ");
       steps = gethex();

       if(steps==0)
          use_switch(speed,dir);

       drive_stepper(speed,dir,steps);
   }

}


Seconds Timer

///////////////////////////////////////////////////////////////////////
////                          EX_STWT.C                            ////
////                                                               ////
//// This program uses the RTCC (timer0) and interrupts to keep a  ////
//// real time seconds counter.  A simple stop watch function is   ////
//// then implemented.                                             ////
////                                                               ////
//// Configure the CCS prototype card as follows:                  ////
////     Insert jumpers from: 11 to 17 and 12 to 18.               ////
///////////////////////////////////////////////////////////////////////

#include <16C84.H>

#fuses HS,NOWDT,NOPROTECT

#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_A3, rcv=PIN_A2)


#define INTS_PER_SECOND 76     // (20000000/(4*256*256))

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

#int_rtcc          // This function is called every time
clock_isr() {      // the RTCC (timer0) overflows (255->0).
                   // For this program this is apx 76 times
    if(--int_count==0) {           // per second.
      ++seconds;
      int_count=INTS_PER_SECOND;
    }

}


main() {

   byte start;

   int_count=INTS_PER_SECOND;
   set_rtcc(0);
   setup_counters( RTCC_INTERNAL, RTCC_DIV_256);
   enable_interrupts(RTCC_ZERO);
   enable_interrupts(GLOBAL);

   do {

      printf("Press any key to begin.\n\r");
      getc();
      start=seconds;
      printf("Press any key to stop.\n\r");
      getc();
      printf("%u seconds.\n\r",seconds-start);

   } while (TRUE);

}


Simple A/D

/////////////////////////////////////////////////////////////////////////
////                          EX_ADMM.C                              ////
////                                                                 ////
////  This program displays the min and max of 30 A/D samples over   ////
////  the RS-232 interface.  The process is repeated forever.        ////
////                                                                 ////
////  Configure the CCS prototype card as follows:                   ////
////      Insert jumpers from: 11 to 17, 12 to 18 and 9 to 16        ////
////      Use the #9 POT to vary the voltage.                        ////
/////////////////////////////////////////////////////////////////////////

#include <16C71.H>

#use delay(clock=15000000)
#use rs232(baud=9600,xmit=PIN_A3,rcv=PIN_A2)

main() {

   int i,value,min,max;

   printf("Sampling:");

   setup_port_a( ALL_ANALOG );
   setup_adc( ADC_CLOCK_INTERNAL );
   set_adc_channel( 0 );

   do {
      min=255;
      max=0;
      for(i=0;i<=30;++i) {
         delay_ms(100);
         value = Read_ADC();
         if(value < min)
            min=value;
         if(value > max)
            max=value;
      }
      printf("\n\rMin: %2X  Max: %2X\r\n",min,max);

   } while (TRUE);

}


Output Listing

....................       min=255; 
008D:  MOVLW  FF
008E:  MOVWF  28
....................       max=0; 
008F:  CLRF   29
....................       incc=TRUE; 
0090:  BSF    2B,0
....................       for(i=0;i<=30;++i) { 
0091:  CLRF   26
0092:  MOVLW  1F
0093:  SUBWF  26,W
0094:  BTFSC  03,0
0095:  GOTO   0AC
....................          delay_ms(100); 
0096:  MOVLW  64
0097:  MOVWF  2C
0098:  GOTO   02D
....................          value = Read_ADC(); 
0099:  BSF    1F,2
009A:  BTFSC  1F,2
009B:  GOTO   09A
009C:  MOVF   1E,W
009D:  MOVWF  27
....................          if(value < min) 
009E:  MOVF   28,W
009F:  SUBWF  27,W
00A0:  BTFSC  03,0
00A1:  GOTO   0A4
....................             min=value; 
00A2:  MOVF   27,W
00A3:  MOVWF  28
....................          if(value > max) 
00A4:  MOVF   27,W
00A5:  SUBWF  29,W
00A6:  BTFSC  03,0
00A7:  GOTO   0AA
....................             max=value; 
00A8:  MOVF   27,W
00A9:  MOVWF  29
....................       } 
00AA:  INCF   26,F
00AB:  GOTO   092
....................       if (incc) 
00AC:  BTFSC  2B,0
....................         counter++; 
00AD:  INCF   2A,F

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