I'm trying to build a parallel port AVR programmer cable.
Surprisingly, this is turning out to be the most complex part of programming my ATTiny13. (I already know I'm going to use WINAVR and AVRDUDE; the tough part for me is building the cable.)
I'm planning on building this:
I bought a male DB25 from Radio Shack (a part I forgot to order from Mouser... but no way I'm paying an extra $6 for shipping just for a DB25!), and am planning on using parallel pins 1, 2, 11, 16, and 18.
I was planning on using a Cat5 cable for the wiring, and using the solid colors only: green, blue, orange, brown, and using the white striped wires for shielding to minimize crosstalk.
But wait... I need 5 wires. Cat5 (with shielding) only gives me 4.
So, I've got a few options:
1) completely strip the Cat5 wire, and run 5 wires parallel (ugly) to minimize crosstalk; 2) use one of the white striped wires for ground.I'm leaning towards (2), but I'm trying to figure out what I can pair it up with.
What is the function of the RESET pin when programming an AVR? Does it pulse, or is it steady...? I'm guessing SCK, MOSI and MISO will be pulsing like crazy, and might introduce crosstalk...
Or am I worrying too much?
Advice requested.
Thanks,
Michael