DPRG mailing list archives: [DPRG] Call for reinforcements

Sat Feb 3 17:09:44 CST 2007

Eric,

I thought of this earlier but didn't say anything (shame on me).  last two
responses now have me wondering.  Is it possible that one of these
connections is shifted to RS-232 levels while the other connection is at TTL
level?  I started wondering this when you mentioned that both TX and RX are
on the same pin.  That tells me that the line is not at RS232 levels.  If
the other board really does have an RS-232 level shifter on it (likely) you
are probably just driving one of the devices into CMOS latchup.  This case
can have all sorts of hard to diagnose symptoms because it may not hit the
part of the silicon die that you would expect...   Take a look at the spec
sheet for the output levels on both boards and make sure they are
compatible.  RS-232 levels direct driving a embedded processor or controller
or anything expecting TTL is not a good thing.

-Hope this helps give you a direction to investigate.

-Kenneth

-----Original Message-----
From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org]On
Behalf Of Eric Sumner
Sent: Saturday, February 03, 2007 4:53 PM
To: Dprglist at Dprg.Org
Subject: [DPRG] Call for reinforcements

I'm all out of ideas on this serial problem, which is starting to look
more and more like a power problem, and I need this to work tomorrow.
So, I'll buy dinner for anyone who shows up at SMU this evening and
helps get this thing working.  Call me at 214-245-6083 if you need to
know how to get here, as I won't be checking email often.

  -- Eric
_______________________________________________
DPRGlist mailing list
DPRGlist at dprg.org
http://list.dprg.org/mailman/listinfo/dprglist