Parallel Port Power Off

pete1234 · 03-01-2007, 03:13 PM

I'm wondering if there is a way to turn power to the parallel port off. I'm drawing 3.5V from the port to power a small circuit, and I'd like to be able to control it's power state. Any help is appreciated.

michaelk · 03-01-2007, 04:48 PM

What pins are you using for power and can you provide a description of your circuit? It is easy to create a program to toggle data or status lines. Google linux parallel port programming for some examples. I also suggest googling for information on how the parallel port works. BTW you can damage the port very easily if you draw to much current.

pete1234 · 03-01-2007, 08:09 PM

I've googled, but I couldn't find a simple solution to just turn off power to the port. I'm using pin 6 and pin 18 (pins 25 through 18 are soldered together). There's no circuit to describe, I'm just fooling around. I'd finished my serial port radio transmitter and I had a few parallel cables lying around and figured I'd give those a whirl.

michaelk · 03-02-2007, 06:11 PM

BTW pin 6 is data bit 4. Its not a matter of turning on/off the port but changing the state of the desired data/status bit(s). The parallel port is a TTL device i.e. A logic 0 is 0 - 0.8 and a logic 1 is 2.4 - 5 volts.

http://www.faqs.org/docs/Linux-mini/...amming.html#s9
http://www.epanorama.net/circuits/parallel_output.html
http://parapin.sourceforge.net/

As previously stated you can eaisly damage the parallel port.

pete1234 · 03-02-2007, 06:59 PM

Thanks for the reply. I guess I'll look into parapin.