I want to use my pc to imput data when a motion detector detects movement.
I've read that LPT port can handle 5V. But what about current? I'd like to test with a small transformer. The transformer outputs 4.5V with 2.5A. Will that damage the printer port should should I cut the current with resistors?
I have sofware that can poll the status of port status. If the transformer is OK where do I connect the hot and ground wire coming from the transformer?
Probably. Using opto-isolators is always a fine idea. But you'd do well to search the web for articles on parallel port interfacing.
I have some OLD but maybe useful stuff on parallel port HERE:
Terry's write up on the hardware is helpful, but writing directly to I/O ports is more complicated under modern windows ( W2K, XP, Vista) than under DOS and Win9x.
Here's a detailed, step-by-step How-To for GUI-based programs to control the parallel using Visual Basic 2005 Express Version (a free download from MS). You can also just download the source code.
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Marc_F_Hult
Some old but simple parallel port stuff that will work on XP machines.
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