Maskinnära programmering 6B2266

Programexempel frekvensmätning med 16F628
/* fmeas62x.c frequency measurement for 16F628 */
/* input frequency 100 Hz - 10 kHz at CCP1-pin */
#include "16f628.h"
#include "math16.h"
#pragma config |= 0x3ff1
/* function prototypes */
void unslongtoa( unsigned long ); /* in ascnum.c */
void initserial(); /* in seriF62x.c */
bit putchar( char ); /* in seriF62x.c */
void delay( char ); /* in delays.c */
void string_out( void ); /* in stringIO.c */
char text1( char ); /* function prototype */
char s[11]; /* Global char array for digits */
#include "seriF62x.c"
#include "ascnum.c"
#include "stringIO.c"
#include "delays.c"
void main(void)
{
char i;
uns16 T, f, t1, t2;
initserial();
TRISB.3 = 1; /* CCP1-pin is input */
/* Settings */
/* "--"."Prescale 1/1"."osc shut off"."synchr"."fosc/4"."on" */
T1CON = 0b00.00.0.0.0.1 ;
/* "--"."--"."Capture each pos edge" */
CCP1CON = 0b00.00.0101 ;
while(1)
{
CCP1IF = 0 ; /* reset flag */
while (CCP1IF == 0 ); /* wait for capture */
t1 = CCPR1H*256;
t1 += CCPR1L;
CCP1IF = 0 ; /* reset flag */
while (CCP1IF == 0 ); /* wait for next capture */
t2 = CCPR1H*256;
t2 += CCPR1L;
/* Calculations */
T = t2 - t1; /* calculate period */
f = 1000000/T; /* calculate frequency */
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