[time-nuts] GPS DO Alternatives

Hal Murray hmurray at megapathdsl.net
Sun Dec 9 07:14:23 UTC 2012


albertson.chris at gmail.com said:
> What if I use a flip flop.  The PPS from the GPS connects to the "set" input
> of the FF and also to the Arduino interrupt.   The output of the OCXO goes
> to the reset pin of the same FF. 

I don't think that is going to do what you want.  The problem is what happens 
if set and reset are on at the same time?

If I was doing that, I'm make the PPS from the OCXO 50% duty cycle and use 
the PPS from the GPS as a clock with the PPS from the OCXO as the data input.


Which brings up another worm for the can.  How are you going to get a PPS 
from the OCXO?  That's going to be hard without some soldering.  My straw man 
would be to use the OCXO to clock whatever uP you end up using and generate 
the PPS with a counter/timer.

An alternative would be 7 TTL chips or a CPLD/FLGA.


-- 
These are my opinions.  I hate spam.






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