Dwayne:

Just finishing project with similar reqt's.  Using the CCP in Capture mode,
and using TMR1, you can get excellent results.  FWIW:  use a good high freq
crystal.... my measurements are in microseconds and anything but a crystal
will yield inconsistent results. =20

I use ME Basic (OK, I know, BASIC is not cool) but here is my working code
that may provide a start

Detect:
  T1CON   =3D   0x05                     ' TMR1 ON, 1:1 pre-scaler
  CCP1CON =3D   0x05                     ' CCP Capture mode, every rising e=
dge
  PIR1.5 =3D 0                           ' Clear bit 5
  TMR1L    =3D 0                         ' Clear the TMR1L value
  TMR1H    =3D 0                         ' Clear the TMR1H value
  tim1 =3D 0                             ' Reset variable
  while PIR1.5 =3D 0
     nop
  wend
  if PIR1.5 =3D 1 then                   ' Capture occurred on rising edge
    TMR1L    =3D 0                       ' Clear the TMR1L value
    TMR1H    =3D 0                       ' Clear the TMR1H value
    CCP1CON  =3D 0x04                    ' CCP Capture mode, every falling
edge
    PIR1.5 =3D 0                         ' Clear bit 5 (capture occurred in=
fo)
  end if
  while PIR1.5 =3D 0
      nop
  wend
    if PIR1.5 =3D 1 then                   ' Capture occurred on rising edg=
e
    tim1 =3D TMR1H<<8 + TMR1L            ' Retain TMR1 value =3D ON time
    CCP1CON =3D 0x05                     ' CCP Capture mode, every rising e=
dge
    PIR1.5 =3D 0                         ' Clear bit 2 (capture occurred in=
fo)
  end if
  If tim1 <3700  then
      TMR1L    =3D 0                     ' Clear the TMR1L value
      TMR1H    =3D 0                     ' Clear the TMR1H value
      tim1 =3D 0                         ' Reset variable
      goto  Initialize_Detect
  end if

Rich

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Dwayne Reid
Sent: Friday, July 18, 2014 9:01 PM
To: pic microcontroller discussion list
Subject: [PIC] Looking for frequency counter software

Good day to all.

The recent discussion about controlling the frequency of a signal generator
reminded me of a project that I've been meaning to do for years.  But it's
been sitting for so long that I should see if anyone has done anything
similar to what I want.

I have a couple of older BK Precision function generators.  These cover the
range of sub-Hz through, I think, 5 MHz.  They work well but suffer one
tragic flaw: it is not possible to know what frequency you are generating
without using an external frequency counter or scope.

I want to add a digital frequency readout to these units.  There is space i=
n
the upper-left corner of the front panel that is just crying out for some
form of readout.

I've seen a couple of frequency meter projects over the past few years -
most are simple and use a PIC's TMR0 and its' prescaler to measure a signal
up to 50 MHz.  But I'm picky.  I want something that measures and displays
frequency when the generator freq is above, say, 1 KHz but measures period
and converts that period measurement to frequency at lower freqs.  This
allows quick display updates even when generating low-frequency signals.

Bonus points if the unit can also measure and display period as well as bot=
h
positive and negative pulse width.

I could write it myself but surely someone has already done something
similar to this.  I hope.

Any thoughts?

Many thanks!

dwayne

--=20
Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang=
e
your membership options at http://mailman.mit.edu/mailman/listinfo/piclist

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.