Interfacing Arduino with Numeric LEDs


I’m just getting started with Arduino, and would like to learn a simple way to use it to control some numeric LED digit displays that I have lying around.

I don’t have the specifications of the LEDs; all I know is that they’re common cathode, and that their voltage ratings are somewhere between 1V and 2.3V.

From large to small, the following text is imprinted on their sides:

KPS-1106 / A S R N D (corresponding to each lower leg)

I couldn’t find their specifications by doing searches with this text on the web. I haven’t dealt with numeric LEDs before, so I’d appreciate links to any common information regarding how they work as well.



the way I usually figure these out is to put them in a breadboard and test to find the pinouts. Use two wires to test them: one wire connected to Gnd of your 5V power supply, and the other wire connected to +5V through a 330 ohm resistor. Make a drawing as you go, and in no time you'll have the pinout.


Thanks for the quick reply.

Would it be dangerous to use the Arduino's 5V power out (with an external adapter) to do this? I don't have any other 5V supply.

not at all.

you can get up to about 450 milliamps out of the Arduino's 5V supply, which would be enough to power several of those displays.


And how about doing it via USB power? I just noticed that my external adapter isn't working..

sure, just try not to short the connections, as if you do, you will be relying on the short circuit protection inside your computer. It’s standard, but who wants to medd up their USB port?