11/23 clock issue
jnc at mercury.lcs.mit.edu
Thu Feb 5 19:41:00 CST 2015
> From: Brent Hilpert
> Well, try removing W1 to isolate the output of the xtal oscillator E15
> from inverter input pin E4.4.
Thanks! Too late to try it today, but first thing tomorrow..
It seems like every time you answer one of my queries, I smack my forehead
and say 'That's an excellent idea! Why didn't _I_ think of that!?!?' :-)
> If you're not familiar with them, E15 is an integrated xtal oscillator,
> not just a crystal - the crystal and oscillator logic are both in that
I'm not familiar, so thanks for the tip. Wonder where I'll find one if that's
what's bad... :-)
> Could also (with W1 removed) pull E4.4 hi/lo while watching the
> inverter output E4.16 to see if it responds correctly with the
Since it's a tri-state, I may need to hit the enable somehow. Oh, wait, I
see, it's hard-wired on via a pull-down. (I wonder why they needed a
pull-down? And I wonder what the test point is there for?) And I guess I need
like a 5K series pull-up resistor to +5, right? (Ground I can just tie
Anyway, thanks again for the help - very, very useful.
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