ALOT OF LEDS

I need to wire 30 led to the GPIO Pins of the Arduino Uno R3, how to do that? I cannot use Series or Parrellel Circuits.

So . . . . what kind of circuits CAN you use?

Do you want these to possibly all be on at the same time?

A 6x5 anode/cathode matrix arrangement is probably the answer you need.

Kevparang:
I need to wire 30 led to the GPIO Pins of the Arduino Uno R3, how to do that? I cannot use Series or Parrellel Circuits.

That's a problem then.
The Uno hasn't got enough pins for 30 LEDs.

Can you use a 5x6 matrix.

Tell us what you really want to do.
Leo..

So basically I will use GPIO Pins to come the leds in like led 1,3,5,7,9,11,13,15,2,4,6,8...

Go for it

An Uno has 18 GPIO pins, not counting RX and TX.
So you can't connect 30 LEDs directly.

A 5x6 matrix uses 5+6= 11 pins.

There are easier ways to drive 30 or more LEDs.
e.g. with the MAX7219 (64 LEDs).
You can daisy-chain many of these chips, so you can control thousands of LEDs with just a few Arduino pins.
Leo..

Thanks.

I have a MAX7219 breakout board that makes it easy to wire up 64 individual LEDs:
http://www.crossroadsfencing.com/BobuinoRev17/

  1. four cheap shift registers + the ShiftPWM library
  2. a couple of LED drivers: neater, but more expensive

Ontaelio:

  1. four cheap shift registers + the ShiftPWM library
  2. a couple of LED drivers: neater, but more expensive

Are 4 cheap shift registers really going to be cheaper than a single MAX7219?

And you only need 1 resistor with the MAX7219 instead of 5 with a direct wire matrix arrangement.

INTP:
Are 4 cheap shift registers really going to be cheaper than a single MAX7219?

Sure, especially the real Maxim one, not the Chinese fake (although the fakes work ok). Shift registers are also a lot easier to get on a short notice.

INTP:
And you only need 1 resistor with the MAX7219 instead of 5 with a direct wire matrix arrangement.

TS didn’t actually mention matrix arrangement.

Ok, so 1 resistor with MAX7219 instead of 30 individual resistors for 30 LEDs on 30 board pins that don't exist :slight_smile:

$3 from here, have been working ok for me, not an authorized reseller per Maxim.
www.taydaelectronics.com
Parts arrive from CO in the US.