11/23 clock issue
jnc at mercury.lcs.mit.edu
Sat Feb 7 10:47:46 CST 2015
> From: Tothwolf
> Before I forget again, did you check for +5V on pin 1 (enable) when you
> were testing your existing oscillator?
Wow. Never thought to try that. Then again, I don't look for +5V on your
average 74xxx when I'm debugging, either! :-) I mean, it's a trace, the
solder on the pin looks good, that's as far as I go, usually! And there's
nothing shown as connected to that pin on the circuit diagram.
So I looked, and... it's at ground (or floating). The only pin that has
anything is 14, at +5V (expected). But I looked online for some datasheets
for similar oscillators, and some of them say 'pin 1 - N/C'. Are yours
tri-state? (That's the enable pin on the tri-state ones.)
I suppose even if yours are tri-state, I can still use them; a quick ohmmeter
check shows that pin 1 isn't connected to either power or ground, so I can
probably tie it high (via a resistor, which in addition to being normal
practise, will prevent a major disaster in case I'm confused - a state I'm
often in :-).
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