by HWman on Tue Oct 04, 2005 8:32 am
I expect that the LED is controlled through some other device and you want to get it's state to the PC through parallel port.
One idea to get the state of LED to computer is to take a suitable optical sensor and put it near the LED in such way that the light from LED shines to the sensor well, but no light from other soruces can get to your sensor. Then just wire the state of the sensor to the PC parallel port input pin. In simplest cases just wiring a phototransistor
There is some information on parallel port input also at
http://www.epanorama.net/circuits/parallel_output.html
Also check "http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm" at
http://ourworld.compuserve.com/homepage ... /page6.htm
From theat document you cn find the circuit
I think the idea would work just putting the phototransistor in place of one switch in the circuit.
I expect that the LED is controlled through some other device and you want to get it's state to the PC through parallel port.
One idea to get the state of LED to computer is to take a suitable optical sensor and put it near the LED in such way that the light from LED shines to the sensor well, but no light from other soruces can get to your sensor. Then just wire the state of the sensor to the PC parallel port input pin. In simplest cases just wiring a phototransistor
There is some information on parallel port input also at
http://www.epanorama.net/circuits/parallel_output.html
Also check "http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm" at
http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm
From theat document you cn find the circuit
[img]http://ourworld.compuserve.com/homepages/Bill_Bowden/p_input.gif[/img]
I think the idea would work just putting the phototransistor in place of one switch in the circuit.