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

John Ackermann N8UR jra at febo.com
Wed Apr 1 23:32:40 UTC 2009


Hi Bruce --

Good point; I'll leave it to the software guys to figure that out. :-)

John
----

Bruce Griffiths said the following on 04/01/2009 06:11 PM:
> John
> 
> Providing a 5MHz output will be difficult/impossible if the PIC is
> clocked at 10MHz as a pin will have to be toggled with every instruction.
> Surely this will leave no time for executing other instructions to
> produce other output frequencies?
> 
> It may be possible to do this using inline code with no conditional
> branches if and only if one can loop back to the start of the code
> without requiring an extra cycle.
> It would probably be easier to use a dedicated hardware divider
> (external flipflop or internal timer) to generate the 5MHz output.
> 
> Bruce
> 
> John Ackermann N8UR wrote:
>> 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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>>   
> 
> 
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