[time-nuts] PPS Divider (John Ackermann N8UR)

[Richard H McCorkle]

John,

Output frequencies above 10 KHz with the PIC divider require separate
manipulation of the port bits within the main timing loop. A 100 KHz
output can be added this way as tvb did in his original divider code,
but if you also want the divider to work properly with both 5M and
10M input rates the bit manipulation code gets a little dicey. For
the faster rates I recommend using one of the output port bits as a
reset line to start an external high speed divider exactly in sync
with the first PIC output. The external divider provides the 1MHz
and 100 KHz outputs and the PIC provides the 10 KHz to 1PPS outputs.

Richard


> You could probably get those output frequencies with a custom version of
> the PIC code.  There shouldn't be any hardware changes needed, though
> the circuit board layout wasn't optimized for high frequencies so no
> guarantee on 5 MHz.
>
> The PIC source code will be available, so anyone who wants to modify it
> for other outputs can have at it.
>
> John
> ----
>
> Mitchell Janoff said the following on 04/01/2009 05:37 PM:
>> In your post, you mentioned that the TADD-2, will have six low impedance
>> outputs that can be individually jumpered to 1 PPS or 10 Hz through 10 kHz
>> outputs. I was wondering if there was a way to provide outputs of 100k, 1MHz
>> and 5MHz (assuming a 10MHz source). I am looking for a way to use a single
>> source such as a z3801 as the standard for my various counters and clocks.
>> There was also a post to build this using divide by 10,2 and 5 IC's. If
>> someone is going to build this circuit can they provide the schematic? If
>> there multiple people interested we can have a circuit board created for
>> this project.
>>
>> Thanks,
>>
>> Mitch
>> KC2MFB
>>
>>
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