[time-nuts] Trimble Thunderbolt 1pps

Attila Kinali attila at kinali.ch
Fri Jan 3 22:56:05 UTC 2014


On Fri, 3 Jan 2014 13:12:52 -0800
Chris Albertson <albertson.chris at gmail.com> wrote:

> The TTL level PPS did not work for me when I tried to drive a long cable.
>  I used the MAX232 level converter chip to level shift.
> 
> Do check the polarity.  If you get it wrong it will appear to work but the
> timing will biased by the pulse width. (the falling edges is used if you
> get it wrong.   RS-232 levels are backwards from TTL except control
> signals.   Just be sure you have the "correct" number of inverter.  Then
> when you are done check the time is right.

Also keep in mind that RS-232 relies on the voltage going negative
to encode a "1". I.e. getting 0V is not enough and might only work
by chance with some RS-232 receivers.


			Attila Kinali

-- 
I pity people who can't find laughter or at least some bit of amusement in
the little doings of the day. I believe I could find something ridiculous
even in the saddest moment, if necessary. It has nothing to do with being
superficial. It's a matter of joy in life.
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