Is there anyone who knows of any good websites or books that talk about C++ programming dealing with the parallel port? I’m trying to build a car MP3 player using an old computer and I will need to hook up to the parallel port in order to control play and such. On a somewhat related note I am also trying to hook up LED’s running off the parallel port, So I’m looking for info on that as well. I’ve used google but I keep coming up with other programming languages instead of C++. FYI - I am currently using Microsoft Visual Studio .NET to code and compile. Thanks in advance for any info you have found!
The best source (and you can buy his book as well) that I’ve found is: http://www.lvr.com/parport.htm
In particular, go to his FAQ. You need to tie at least one pin high and a couple others low to fake out the Windows driver.
I’ve used the parallel port as a means of controlling some custom boards using Visual C++ (but not .NET), and may be able to help as well. I’ve simply done a “CreateFile” with “LPT1:”. and then done WriteFile’s to control the various bits. Once you take care of the signals (see the FAQ) to fake out the driver, it’s pretty simple.
(If you haven’t faked out the driver, when you do a WriteFile, your application will just hang there forever).
One warning on using it to for control, there is some pretty serious “bounce” on the parallel port lines. You will want to make sure that whatever you’re controlling won’t be affected by this (we had to add de-bounce circuits).
Another warning. If your old computer is a laptop, be aware that laptop lpt ports often don’t put out as “solid” of a voltage as a typical desktop. A desktop will usually get pretty close to the 0 and 5 volt rails. A laptop will be within TTL specs, but won’t go to the rails and won’t have as much drive capability. All you need to do is add a driver chip for the LEDs so it’s no big deal.