[time-nuts] GPS DO Alternatives
lists at rtty.us
Sun Dec 9 14:06:23 UTC 2012
The flip flop would have a metastable region. It would be quite narrow, but it would be there. As soon as you try to take the square wave into the processor, you are right back to the same problems we've discussed before. The flip flop, run this way does not improve that part of the situation.
On Dec 9, 2012, at 2:14 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 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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