[time-nuts] M12+T Oncore

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jul 3 00:01:02 UTC 2009


A monostable is not required as the PPS pulse width is 200millisec wide.
The PPS pulse can either stop when the timing error is too high/too few
satellites etc., or it can be configured to continuously output.
Since the M12+T can be configured for either a 100Hz output or a 1PPS
output using a monostable adds unnecessary complication.

If the buffered PPS output is intended to drive 50 ohms a driver that
has a clean output that doesn't produce aberrations of 20% or so due to
ground bounce would be nice.

Bruce

Hal Murray wrote:
>> Specifically it would provide regulated 5 and 3 volts, a MAX3232 chip
>> for level translation, a buffered 1PPS output, and LEDs to indicate
>> power and 1PPS heartbeat. Some or all the components would be SMDs.
>> This could be an assembled board or a kit. 
>>     
>
>   
>> If this looks promising, I would be interested in what other features
>> would be desirable.
>>     
>
> How wide is the PPS?  If it's tiny (10 microseconds) some serial port setups 
> won't catch it.  If so, a one-shot pulse stretcher would be handy.
>
> Does the PPS signal stop ticking when it runs out of satellites?  If so, I 
> think you can use the other one-shot in the package so that the LED is on 
> when the PPS is ticking and blinks when the PPS is off. and is off if there 
> is no power).
>
>
>
>   






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