[avrdude-dev] [patch] support for bidirectional printer ports, including exit codes

[Alexander Stohr]

Hello,

the attached patch is built against CVS sources from today
and adds enhanced functionality in respect to 
bidirectional printer ports to avrdude.

the code explicitely programs  the PPI-Databits 
direction to output on interface opening.

it further extends the commandline option 
"-E" for exit state specification
so that "bidirinput" and "bidiroutput"
can be specified and gets carried out.

furthermore all PPI related code got moved to the ppi source file 
that was explicitely marked as a TODO in main.c of the sources.
this means code is much more modularized now.

as a final cosmetic change, the ppi headers not only do define 
the parport register offsets but do define the register bits via an enum.
this is nicely used in the pin number to register and bitmask table 
in par.c source file thus making it much more human readable.

okay, its a medium size patch, but it all looked reasonable to me
to perform all those changes in a single pass rather than iteraring.

-Alex.

PS: i have the atmega128 development board.
i used the well known "avrdude-simple/bsd/Alf" wiring sheme
for my parport programmer cable sheme and it nearly worked.
just for the SCK i needed a serial 100 Ohms resistor 
for decoupling in normal operation (e.g. with SD card) 
because the parpaort drove some 0.2 mA trough the pull up resistor 
R12 (10 kOhms) on the development board.
this was meaning a nonacceptable voltage drop of about 2 V for high level.

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avrdude-bidir.diff.bz2
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