[time-nuts] Oncore 1pps driver & LED

Randy Warner Randy at synergy-gps.com
Thu May 4 15:19:11 EDT 2006


You "should" be alright. You're driving a lot of CAT5, but since the
data is only at 9600 baud you should be OK. The 1PPS on the DCD line
will be fine too. To blink an LED you just need to buffer the 1PPS
signal coming out of the UT+ as it does not have enough drive capacity.
Just about anything will work: IC buffer or inverter (I use standard
74LVC04's in my designs) or just a simple xstr inverter or emitter


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Glenn
Sent: Thursday, May 04, 2006 11:56 AM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Oncore 1pps driver & LED

 I am hoping someone can help me with some basic electronic questions
about hooking up the Oncore UT+.

I have a MAX233CPP two channel rs232 driver. I presume I can use the
second channel to drive the 1pps on DCD line. Yes? I'll have a run of
about 30-50' of CAT5, which *should* work. I should be able to adjust
the 1PPS offset on the Oncore to account for this, plus the delay of the

The 7805 +5v voltage regular appears to be plug&play. I don't think I'll
need a heat sink for it.

The Linux PPS driver appears to only support kernel 2.4. And, I'd rather
stick with a stock kernel on that box anyway. So, I'll follow Geoff's
advice and run FreeBSD on an old Compaq for my timeserver. But, I'll
probably test everything out on my linux box before I get around to
building the FreeBSD box.

I'd like to put an LED near the Oncore module that blinks on the 1pps. 
What's the best way to wire this up?


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