[time-nuts] What's the easiest way to divide by 10 for Thunderbolt reference output?

[Bob Camp]

Hi

With some micros you can play with the PWM outputs to get a bit faster than the instruction cycle would allow. There are always constraints (like binary division) on that as well.

Bob

On Jul 24, 2012, at 5:21 PM, John Ackermann N8UR wrote:

> TVB can give a better answer, but in general the number of clock cycles required per instruction limits the minimum divide ratio.
> 
> Tom whipped up a special PIC to get the highest possible output rate for a set of tests we were doing, and given the 20 MHz maximum input clock, we got about 800 kHz output.
> 
> John
> ---
> 
> On 7/24/2012 1:05 PM, Chris Hoffman, KG6O wrote:
>> John,
>> 
>> That's interesting to me. What exactly are the actual structural limitations of [that] pic?
>> 
>> -CH
>> 
>> On Jul 24, 2012, at 7:55, John Ackermann N8UR <jra at febo.com> wrote:
>> 
>>> Unfortunately, the TAPR T2-Mini divider (http://www.tapr.org/kits_t2-mini.html) can't quite get to 1 MHz from 10 MHz with the PIC divider chip due to limitations in the chip architecture.
>>> 
>>> However, nothing says you couldn't "dead bug" in a decade divider chip in place of the PIC, and let the T2-Mini provide the input conditioning, output driver, voltage regulation, connectorization, etc. for you, making it much a smaller project.
>>> 
>>> John
>>> ----
>>> 
>>> On 7/24/2012 8:18 AM, Chris Wilson wrote:
>>>> 
>>>> 
>>>>  24/07/2012 13:14
>>>> 
>>>> My Racal Dana 9908 can take a 1 Mhz external reference. Inputting my
>>>> Thunderbolt at 10 MHz works, but shifts the decimal point over. I am
>>>> not sure if this has any other detrimental effects as to accuracy or
>>>> other? What's the easiest way to have a 1 MHz reference from the
>>>> Thunderbolt for this timer / counter please, yet retaining 10 Mhz for
>>>> my other devices that want a 10MHz reference signal?  Thanks.
>>>> 
>>> 
>>> 
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> 
> 
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