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'[PIC] Solved? (sorta) Pin sharing between clock an'
|I tracked it down to the clock that is the issue, as the I/O works fine
on the shared port/bit (PortD-5). If anything, you would think that's
the one that would have problems being that it's a switching I/O port.
So, that just leaves the clock that works on PortB-0, but not on shared
Well, I tried changing the timing (adding NOPs) before and after reading
the bit, and that made no difference. I am right at the 200 nS minimum
bit available time spec, but that same code worked fine with the
dedicated bit (PortB-0). I also made sure I cleared port D at the
beginning of the clock subroutine just so I start with a known state.
Then, I tried port D-0 (also shared), and it worked! That's odd because
D-0 is also shared with the LCD display data. So, I tried D-5, and that
So, I moved the clock to D-7 and moved the I/O to D-6 since I wanted
them to use consecutive port bits. And that works. FYI, the RST line is
dedicated since it controls when the clock is accepting data input.
So, the question is: Why does the clock signal not work on D-6, but it
works on (seemingly) any other bit on the same port, and why does the
I/O work on D-6?
Yes, I made sure there was nothing other than the LCD and this clock
chip using ports D5, 6, and 7.
While this will work, I would like to understand what was wrong.
Spehro Pefhany wrote:
I should note that when I say "clock", I'm talking about the CLK signal,
not the clock chip itself.
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