I am playing with a project to display statuses using the computer parallel port and 5v leds. First let me say that I am a programmer and weak at electronics. I have a number of demo programs that read and write to the parallel port.
When I put a meter to one of the ground pins and check the (8) data pins, I don't get the expected results. Pins 2-4 (bit 0-2) always have power even when I read the port and it has a zero value. If I set the value to 255, then all of the data bit are on. If I set the value to 128 then pin 5 bit 3 goes on. Using values between 128 - 255, it appears that I can set pins 5-9 (bits 3-7), just not pins 2-4. Any ideas what is happening? Once (if) I get this resolved, I will need help with LEDs and resisters.
Update: I need to do some more research. It appears that the pins are reversed. Pin 2 is on the top left versus the diagram that I have has it on the top right. Female diagram,male pins.
When I put a meter to one of the ground pins and check the (8) data pins, I don't get the expected results. Pins 2-4 (bit 0-2) always have power even when I read the port and it has a zero value. If I set the value to 255, then all of the data bit are on. If I set the value to 128 then pin 5 bit 3 goes on. Using values between 128 - 255, it appears that I can set pins 5-9 (bits 3-7), just not pins 2-4. Any ideas what is happening? Once (if) I get this resolved, I will need help with LEDs and resisters.
Update: I need to do some more research. It appears that the pins are reversed. Pin 2 is on the top left versus the diagram that I have has it on the top right. Female diagram,male pins.
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