Capture woes...

[ardhuru]

I need to measure the RPM of a motor that would range from about 300 to 2000. Based on a thread in which Bruce had given code to measure the pulse width (only the width, not the frequency) of a signal using the capture function, I used the following code, modified for frequency. I used a square wave generator to test out the code, and the numders I get dont match up at all.

Its a 16F628A running the internal oscillator.

INTCON = 0 ' Interrupts off


CCP1CON = %00000101 ' Capture mode, capture on rising edge
T1CON = 0 ' TMR1 prescale=4, clock=Fosc/4, TMR1=off
T1CON.4 = 0
T1CON.5 = 1

CLEAR

Reload:
TMR1H = 0 ' Clear high byte of TMR1 counter
TMR1L = 0 ' Clear low byte
T1CON.0 = 1 ' Turn TMR1 on here

Capture = 0 ' Clear capture int flag bit
While !Capture ' Wait here until capture on rising edge
Wend

T1CON.0 = 0 ' Turn TMR1 off here

' Rising edge detected / stuff 'captured' Timer1 value in T1
T1.HighByte = CCPR1H
T1.LowByte = CCPR1L

DEBUG #T1,13,10

GOTO ReLoad


I'm also attaching a screen grab of my calculations.

Any idea where the problem is, guys?

Thanks,

Anand