SocMatt

Hi

I need a frequency counter and had success using the example code ex_freqc.c, however now i need the frequency counter to work over two channels.
Can i reproduce the code for two channels or is it specific to that input pin of the PIC.

Any help would be most appreciated

Matt

falleafd

Post the code upto here, because some of us dont use CCS C, so if you have the code, it's easier for people to help you.

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Falleaf
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English forums at PIC Vietnam - Vietnamese Electronics forums
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Distributor of Microchip in Vietnam

SocMatt

Here is the code:

#include <16F876.h>
#fuses HS, NOPROTECT, NOPUT, NOWDT, NOBROWNOUT
#use delay(clock=20000000) //one instruction=0.2us
#use rs232(baud=57600,parity=N,xmit=PIN_C6,rcv=PIN_C7,b its=8)
#bit t1_overflow=0x0A.4

// #bit t1_overflow=0xF9E.0 (PIC18, Reminder)

void main() {
int cycles8, cycles;
int32 freq;
long freqc_high;
long freqc_low;

while (TRUE) {
cycles8=0;
cycles=0;
freqc_high=0;
t1_overflow=0;
set_timer1(0);
setup_timer_1(T1_EXTERNAL|T1_DIV_BY_1);
/* ___ wait one second ___ */
while (cycles!=0xFF) { //true=3, false=4
cycles8=0; //1 cycle
//start inner loop
while (cycles8!=0xFF) { //true=3, false=4
if (t1_overflow)//true=2,false=3 //----|
{t1_overflow=0;freqc_high++;}//6 cycles // |
else // |-- 8 cycles
{delay_cycles(5);} //----|
delay_cycles(62); //x
cycles8++; //1
///2 cycles to jump to top
//math: end inner loop
//math: total inner loop=((3+8+x+1+2)*255 + 4)*255
//math: if x=62.87781 then inner loops takes 5mil instructions
//math: if x=62 then inner loop takes 4942920, have to fill 57080 cycles
}
delay_cycles(216); //y
cycles++; ///1 cycle
///2 cylces to jump to top
//math: outer=(3+1+y+1+2)*255+4=57080
//math: y=(57080-4)/255)-(3+1+0+0+1+2)
//math: if y=216.827450980392156862745098039216 then outer loop cylces is 57080
//math: if y=216 then outer loop cycles is off by 211 cycles. z=211
}
delay_cycles(211); //z
/* ___ end waiting 1 second ___ */
setup_timer_1(T1_DISABLED); //turn of counter to prevent corruption while grabbing value
if (t1_overflow) //check one last time for overflow
freqc_high++;
freqc_low=get_timer1(); //get timer1 value as the least sign. 16bits of freq counter
freq=make32(freqc_high,freqc_low); //use new make32 function to join lsb and msb
printf("%LU Hz\r\n",freq); //and print frequency

}
}


Cheers