On Mon, 9 Feb 2004 07:11, James Nick Sears wrote:
> How are you connecting to your PIC.  I would try using Timer1 with TMR1CS
> set (Timer1 clocks on the rising edge of RC0)  Then you can clear Timer1
> and it will count rising edges until it overflows or you clear it again.
> Make sure your prescaler settings, etc. are appropriate.
>
Thanks Nick, and everyone else who replied to my earlier pulse counting
question. Unfortunately, I couldn't get the RC filter idea to work and due,
partly to storm damage, I had abandoned the project but have now decided to
have another look at it again purely for programming practise (this is my
first project, by the way).

The way I understand timer1's use is that a rising edge on port C0 (16F876A)
causes TMR1L to increment and overflow into TMR1H. So far that doesn't happen
and I suspect that there is more to it than just setting a few bits in the
T1CON register.

This is my initialisation code:

clrf       PORTB                ; Initialise Port B
clrw                                ; Clear W register
bsf        STATUS,RP0      ; Select Register Bank 1
movwf  TRISB                 ; Set port B to all outputs
movlw   b'00000001'
movwf   TRISA                ; Port A0 input the rest outputs
movlw   b'00000011'
movwf   TRISC                ; Port C0 & C1 inputs the rest outputs
bsf         T1CON,0           ; Enable timer1
bsf         T1CON,1           ; External clock input from C0
bsf         T1CON,2           ; Don't sync external clock input
movlw    0x06
movwf    ADCON1           ; Set port A to digital i/o
bcf          STATUS,RP0     ; select Register Bank 0

The remainder of the code reads TMR1L and TMR1H (I took this from the
Microchip's docs) and then displays the result on a LCD display. The counter
register is always 0 and the display code actually works.

Is there more to it? Are there other registers that I have to deal with? I
have searched for example code without success.

--
Regards,
Phil.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body