Hey guys,
So I'm just trying to understand the capture module on the PIC16f887. I have some code which attempts to capture an 82.4 Hz frequency (this is going to be adapted later for a guitar tuner) and if the frequency captured is within 5 cents of that value it should set portb to 82 just for visual confirmation that it is working. My input to the CCP1 pin is a square wave from 0 to 6 volts at 82.4 Hz.
All I know is that it isn't working, however, the capture module has been working for other programs I've written so that isn't the issue.
Thanks for the help!
So I'm just trying to understand the capture module on the PIC16f887. I have some code which attempts to capture an 82.4 Hz frequency (this is going to be adapted later for a guitar tuner) and if the frequency captured is within 5 cents of that value it should set portb to 82 just for visual confirmation that it is working. My input to the CCP1 pin is a square wave from 0 to 6 volts at 82.4 Hz.
All I know is that it isn't working, however, the capture module has been working for other programs I've written so that isn't the issue.
Thanks for the help!
Rich (BB code):
#define _LEGACY_HEADERS
#include <htc.h>
__CONFIG(INTIO & WDTDIS & PWRTDIS & BORDIS & BORDIS & LVPDIS & DEBUGEN & DUNPROTECT & UNPROTECT);
#define first_time 0
volatile int capreg_new, capreg_old,tau;
volatile char time=0;
void main(){
ANSEL=0; //This and next line initialize PORTB to digital
ANSELH=0; //
PORTB=0;
TRISB=0b00000000; //PORTB all outputs for lights
TRISC=0b11111111; //PORTC inputs for CCP
// CCP1CON=0b00000101; //Capture initialize
T1CON=0x01; //Timer on
PEIE=1; //Enable peripheral interrupts
GIE=1; //Enable Global interrupts
CCP1IF=0;
CCP1IE=1; //Need this?
while(1) {
CCP1IE=1;
CCP1CON=0b00000111; //Capture initialize
}
}
//*********** Interrupt Service Routine *************//
void interrupt isr(void){
if(CCP1IF==1){
CCP1IE=0; //Turn off interrupt so it doesn't stick in isr
if(first_time == time){
CCP1CON=0x00;
capreg_old=CCPR1H;
capreg_old=capreg_old<<8|CCPR1L;
}
// PORTB=PORTB++;
if(first_time != time){
CCP1CON=0x00;
capreg_new=CCPR1H;
capreg_new=capreg_new<<8|CCPR1L;
tau=capreg_new-capreg_old;
if(tau>12000 && tau<12271) PORTB=82;
capreg_old=capreg_new;
}
time=1;
CCP1IF=0;
}
}
