[time-nuts] Thunderbolt PPS Modification

Hal Murray hmurray at megapathdsl.net
Sun Sep 26 05:27:09 UTC 2010


> Problem 2:  Because you connected the TTL-level 1 PPS to the RS-232, you
> may find that not all computers will recognize it.  A computer that
> actually followed the RS-232 rules wouldn't see it at all.  I don't know  if
> any modern computer actually follows those rules.

I've never had any troubles feeding TTL signals to "RS-232" inputs.

I tried the simple wire first.  It didn't work, so I guessed that my pulse 
wasn't wide enough and built a debugging setup that had a pair of DE-9 
connectors with ground, Rx and Tx jumpered across.  The DCD pins came out to 
a couple of wires so I could easily get at them with clip leads and try 
things.


-- 
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