measure the xtal

[skimask]

Hi, Savnik
An easy solution is to use an external RC circuit and use ... RCTime ( 16 Bits result ...) !!!
calibrate RCTime ( low drift components !!! ) with a Known Freq XTal ...
With another XTal The Result will be proportionnal to the XTal Freq change ...
That's all, Folks !!!
Alain

Won't the output from RCTime be a logarithmic response, in other highly non-linear? You'd probably have to do some serious math to get accurate results.

[Acetronics2]

Won't the output from RCTime be a logarithmic response, in other highly non-linear? You'd probably have to do some serious math to get accurate results.

Hi, Skimask

you Just forgot The XTal range won't be from zero to infinite ... 1 to 20 ... may be.

But, as always, I'm not so sure of what our friend intends to do ...

Alain

[savnik]

But, as always, I'm not so sure of what our friend intends to do ...

I have done a frequency meter with prescaler (256) from 10-1400Mhz.
I did it with pbp(tmr0) and asm.
But now i want to make a frequency meter from 0 -10 Mhz with only pbp.

[skimask]

I have done a frequency meter with prescaler (256) from 10-1400Mhz.
I did it with pbp(tmr0) and asm.
But now i want to make a frequency meter from 0 -10 Mhz with only pbp.

Well, I gave you an idea that I thought was fairly good...whether you use it or not is up to you...either run with it or don't...

[Acetronics2]

Hi, Skimask

I'm out on this one ...

I thought at first Savnik wanted to build some kind of XTal "identifying Gizmo" ...

For a Freq meter, I never found simpler than The µChip AN 50 Mhz freq meter :

1 16F84
1 74HC 132
1 Input Fet
1 LCD ...

rather simple. But works fine. ASM program ...of course.


links to clones :

http://www.sixca.com/eng/articles/fc50/index.html

Note their PCB is to re-design ... too close layers in the P.A. section ... I couldn't measure over 7-8 MhZ with their design.

Got 50+ Mhz with a re-design of PCB ...

and :

http://www.sprut.de/electronic/pic/p...quenz/freq.htm


Also simplified ...

http://l.lefebvre.free.fr/freq/freq_01.html

And the last one :

http://www.artra-qrp.com/fp50/fp50.html



Alain