# 5 LEDS in 4 rows how to???

need help I have a problem m hoping for information..

I have 4 rows of five LED's I need to send information from a data sheet text file that gives numbers for each led and blanks or eqiv for no LED's to light.

So if I input a text with 1, 6, 11, and 16 LED's to light; the output would be Row 1 has its first LED lit row 2 the same and so on.

If no lights are required for a row they need to be out/off.

I have no experience in this and need help so any help would work..

Always respect to those who help =;)

How are the LEDs connected?

I'm wanting them to be run through an UNO I got at radioshack. Ive looked at some samples of code for the software but none of them gave a clear example of what I was looking to accomplish IMHO. I might be wrong though. Anyhow I have an UNO rev 3 kit. I am new at this and very much so green. I have 4 74HC595's but am not sure that this is the chip I need to proceed...

You have some loose LEDs?
4 rows, 5 columns… as a 4x5 (or 5x4) matrix, you could do that with 9 output pins, 4 or 5 resistors, and no auxiliary ICs
Can you solder up and lead out a matrix then?

I don’t know honestly, I’ve been trying to link them through but I have found I can control 8 led’s per IC but I was wanting to know is there a way to do what I am asking with one IC.

I had just Replied that you could do so without any ICs (extra). Not interested? Not good enough?

mynameherebro: I don't know honestly, I've been trying to link them through but I have found I can control 8 led's per IC but I was wanting to know is there a way to do what I am asking with one IC.

With the right IC, yes.

But before we can get to that we need to know how your LEDs are connected. You say "I have 4 rows of five LED's" which implies that they're connected together but they might be just be 20 LEDs in a bag for all we know....

Here’s an example of a 5x5 matrix, delete 1 row, or 1 column, to make it 4x5, or 5x4.
You can control it safely without the transistors (or a driver chip like ULN2003) by only turning on 1 anode high and 1 cathode low at any 1 time. By cycling thru all 20 combinations quickly, (aka multiplexing) you will be using Persistence of Vision to trick the eye into thinking that up to all 20 LEDs are on at the same time. Each needs to be on approximately 1/20 of 24 frames/sec (movie theater rate). So 1/20 x 1/24 sec = 2mS.
If you use a transistor/driver chip, then instead of just 1 LED on at a time, up to 4 (or 5, your call) will actually be on at one time, and the matrix will appear to be brighter over all.
Each Row/column can then be on 1/5 or 1/4 of 1/24 sec = 8 or 10mS.
That 2, 8, 10mS is plenty of time to be doing other stuff.