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LED Matrix

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New Member

I wish to create a rectangular panel of led's that are controlled by a home pc to turn on and off individual led's.

I've worked out pretty much what I need to get it all together except for the interface for PC - LED's. I need something that I can write a driver for to address each led on the rectangular array/matrix individually, being able to turn them on and off. This would then allow for further programming to fully control the led's to form visual parrents etc.

For example on a four led display there would be two led's on each row:

What kind of device would allow me to plugin the inputs from the basic pcb (with a matrix of leds setup on it) and then control the switching on/off of the led's via a computer - through maybe something like rs232 or maybe even usb?


New Member
I think the easiest to interface is the parallel port. And at 8 bits, you could easily set it up to control 2^8 LED's. You just interface then decode the address into LED matrix address.

there are MANY parallel tutorials on the web...epanorama.net (the best!)

good luck,


New Member
LED Matrix - solution

The serial port is easier to read/write from BASIC programs - but a bit slower. I built a circuit based on the 6402 UART (ancient but easy to use), it isn't hard to multiplex up from it's 8 bit output - I have 16 outputs and 8 inputs (intended for rover control).
The beauty of RS232 is that all my computers have a port - even my old Casio pocket computer 8)
Drop us a note (click on PM below) if you want the circuit - several ICs involved :!:


Active Member
I suggest for experimentation purpose use your parallel port (simplest to work). Connect 16 LEDs in 4 x 4 matrix form and you'll have 8 wires to connect to the parallel port. Now connect all these 8 wires to your Data port of LPT ie. Pin No 2 to 9 (D0-D7 in sequence) through 330R resistor in each line. Now to turn on any LED make a partiular column at logic 1 and the particular raw at logic 0. P.S. This 1 and 0 logic will depend how you connected your LEDs i.e. where the anode and cathode are connected.
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