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Strange behaviour, I/O port, 68HC11

Started by bruce varley October 17, 2004

This is probably becoming a legacy topic. I hope there's someone out there
who can assist.

According to the 68HC11 reference manual, Port A PA3-6 can be general
purpose outputs, or driven by timer output compare functions. If one
disables the latter then it should simply be a matter of writing to the PA
register, $1000 to set the pin voltage.

I find that that works fine for PA4-6, but despite many attempts I can't set

All the 'obvious' things have been tried. I've reread chapters 7 and 10 in
the r.m., and AFAICT the registers are set correctly for gen purpose I/O -
OC1M =TCTL1 = CFORC = 0. The pinout diagrams for E2 and E9 chip variants (I
use E2) reference an input compare function for the PA3 pin. There's no
reference to that elsewhere, it could be the problem but I don't know how to
solve it if it is.

I need to use this pin as an output. Can anyone assist? TIA


We need to know what specific device you are talking about. On a A8,
for example, PA3 is an output. Whereas on the E-Controllers, PA3 is
IO. You have to set DDRA3 in PACTL first, if you want that pin being
an output. In addition to the reference manual you should look into
the datasheet of your device.


Ren� K�nig schrieb:
> We need to know what specific device you are talking about.
Now I read your posting carefully enough and saw, that you use an E2. So you have to set DDRA3 in PACTL. Sorry for my first reply. Regards, Rene

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