ok, i want to make two 7x3 LED arrays that i will be able to input text on a PC program controlling it thru either a serial port or a USB-serial adapter. parallel is not an option. they only have to show the same as each other so i guess if i made one "control unit" it could drive both also, the size of the LED array is non-negotiable anyone got any ideas where i should start? i am assuming that i am going to need a microcontroller of sorts. I am willing to pay someone to write software/design the circuit if needs be thanks all!!
Connect them up something like this: http://www.owenthegreat.com/content/smli/images/schematic2.gif Connect the negative sides to the microcontroller, and connect the positive sides through transistors to something like a 4017, 74xx138 or some sort of demultiplexer or counter chip, which your microcontroller is driving. So your firmware cycles through the "rows" really fast, and lights up what's needed in each group. If this occurs sufficently fast, your eyes think it's a constant display.