Problems whith pulsin

[mister_e]

there's probably many method. but did you tried with a sampling time of 10ms with a range of 68 to 82?

Where the pulses cme from? did you monitor it to see if they're clean with the right amplitude?

Before thinking of using internal counter or interupt, can you try the following and post your result?

' Pic 16f84 at xtal 4 Mhz. WDT off PTU off' 
' Detecting 7.5Khz with +/- 10% => from 6.82 KHZ to 8.25 Khz
' measuring the frequency period =>147uSec to 121uSec
'
FI      VAR PORTA.3 'input freq
SO      VAR PORTB.0 'OUPUT LED
W0      VAR byte
TLow    var byte
THigh   var byte

INIT:
    pulsin fi,0,Tlow
    pulsin fi,1,Thigh
    w0=tlow+thigh
    IF (W0<15) AND  (w0>12) then PULSE
    GOTO INIT

PULSE:
    HIGH SO 
    PAUSE 500
    LOW SO
    PAUSE 500
    GOTO INIT
END

make sense to me ... after being more than 24 hours awake...