Reading parallel port voltages in C 3

[coombop]

For a new project that i am doing as a part of a robotics competition, I am trying to find out how to read voltages off of the parallel port in C. I am familiar with the port itself but am a novice C programmer at best. The voltages have to be fairly accurate as they will be used for a thermocouple. Is this even possible?

 

[xwb]

1) Which chip - Motorola, Intel 8255 or something else.
2) Do you have an OS you're running on or is this some embedded system
3) If embedded system and Intel, is it memory mapped or I/O mapped

 

[coombop]

I am just going directly through the parallel port and the sensor is literally just a themocouple designed to report voltages to a computer. I am running XP on the machine that i am using. The only real question that I have is whether the parallel port will just report I/O or if it will report specific voltages.

 

[TrojanWarBlade]

The parallel port is a collection of binary lines (on or off).
Unless your thermocouple has an A2D converter with it I suspect you won't get very far.

TWB.


Trojan.

 

[xwb]

The other problem is that from XP, you cannot access the parallel port directly. Many articles on the net like

http://electrosofts.com/parallel/

will work for DOS/Win95/98/ME but not for NT, 2K, XP and Vista.

You can bypass this by using userport

http://www.embeddedtronics.com/design&ideas.html.

You should be OK as long as that PC is not connected to the net because it bypasses the built in security of NT/2K/XP to give you access to the parallel port. This could be exploited by malicious programs but if you're not connected to the net on that machine, it won't be a problem.

 

[mingis]

Why not simply CreateFile("LPT1", ...)?