I applied various frequencies (PWM) and LCD outputs are as following ;

1kHz >> 11857
2kHz >>  5857
4kHz >> 2857
16kHz >> 607

Timer was expected to counts less in a higher frequency than a lower
one. System responds logically somehow but lacks from precision. It
can be a data conversion typo or etc. My current mental situation is
not suitable to debug more.

On Mon, Nov 28, 2011 at 5:49 PM, Yigit Turgut <y.turgut@gmail.com> wrote:
> Hi all,
>
> Recently I am trying to capture pulse duration using Capture module on
> CCP1 port and print the frequency to lcd. Configuration, timer
> settings, interrupt monitoring etc, everything works as expected
> except one thing ; LCD shows ridiculous values for example it gives
> '11869' value for a 1kHz PWM input. It is responsive to changes in the
> frequency of the applied pwm but not accurate/consistent. This is the
> crippled code not to pollute around ; I am currently using MPLAB C18
> with a target of 18f2550. I can post the entire code as well but the
> mistake lies in this section I suppose ;
>
> void main(void)
> {
> unsigned char config1=3D0x00,timer_value =3D 0x00;
>
> TRISC =3D 0; //all c ports are output
> TRISCbits.RC2 =3D 1; //ccp1 input
>
> SetTmrCCPSrc(T1_SOURCE_CCP); =A0 //Set Timer 1 as source for input captur=
e module
>
> =A0 =A0 =A0 =A0 =A0config1 =3D CAP_EVERY_RISE_EDGE | CAPTURE_INT_OFF ; //=
configure input
> capture for capture on every rising edge and its interrupt off
> =A0 =A0 =A0 =A0 =A0OpenCapture1(config1 );
> =A0 =A0 =A0 =A0 =A0OpenTimer1(0); //start the timer
>
> =A0while(!PIR1bits.CCP1IF); =A0// Wait for event
>
> =A0INCAPResult =3D (int)ReadCapture1(); // read result
>
> =A0display((int)INCAPResult); =A0 // print result on lcd
>
> =A0 =A0 =A0 =A0while(1);
> CloseCapture1();
> }
>
> Connections and configurations are all triple checked and they work.
> But as I mentioned LCD is not returning correct values. Went over the
> code for lots of times without =A0no luck!
>
> Any ideas ?
>
> Have a nice day.
>

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