[time-nuts] Z3810AS PPS to a Raspberry Pi

Chris Albertson albertson.chris at gmail.com
Mon Mar 23 22:25:33 EDT 2015

On Mon, Mar 23, 2015 at 4:58 PM, Pete Stephenson <pete at heypete.com> wrote:

> On 3/23/2015 5:20 PM, Dan Watson wrote:
> > The solution I came up with is very simple but works well. I
> > capacitively couple the signal into a MOSFET which triggers a
> > monostable 555 circuit. This generates a nice clean ~100ms pulse that
> > I send to the PI, and an LED. Because who doesn't like blinking
> > LEDs?

For NTP the 555 is good enough but for any kind of precision timing (where
nanoseconds mater) the capacitive coupling and 555 would introduce a LOT of
noise.  But NTP works at the microsecond level.    I'm surprised to can't
get the Pi to interrupt on the raising edge of the PPS and that you had to
make the pulse longer.

Chris Albertson
Redondo Beach, California

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