cable length

what is the maximum cable length from a pic programmer to the paralel port of the computer it is screened cable

The maximum allowabe cable length for parallel port is 1.5 meters. If you go beyond that, you may get erratic results.

ok well I'll do a meter then just to be sure both ways is there a simple program i could run into a 16F88 or '84 to ensure it is all working ? something fool proof that is if it does not work it mean I built thhe programmer wrong

How are you going to program a 16f88 or 84 to test your programmer? If you can, then I guess it's working! (only kidding)

If you use ic prog (http://www.ic-prog.com/) then there is a hardware testing feature that allows you to turn on programming voltages and shows data states, you can set up/test your programmer in this way.

Hope this helps

If you use Nigel's tutorial 1.2 then when you apply 5V in icprog you can see the data in line pulsing at around 1Hz. This is because it uses the internal oscillator and so will run while in the programmer. This also causes problems on some programmers that raise Vdd before Vpp as the code starts to run instead of the chip going into program mode.

Mike.
Edit, I'm not sure if the above works with a parallel programmer. I think it will. Maybe someone could try it as it's a really simple way to know if a programmer is working or not.

ok thanks I'll do some experimenting

I seem to remember 1.5m being a very old specification for parallel ports. Most modern ones are able to drive up to 32 feet (9.75m). For several years now I have used a 25ft (7.6m) cable for bidirectional communication with my printer without any issues at all.

That being said your limitation will likely be the PIC Programmer itself. It will certainly work at 1.5m and it is likely that longer ones will work too. Parallel cables are cheap. It can't hurt to experiment a little.

phalanx said:

32 feet (9.75m)

Click to expand...

Unbelievable!!!

In the past I have tried using cable length above 2m which never worked even after using buffers.