Pages: [1] 2   Go Down
Author Topic: Arduino MEGA powering 50 RGB LED's  (Read 2550 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 5
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello,

I'm new to the forum (and Arduino), thanks for reading my post.

I'm working on controlling around 50 RGB LED's from software running on a PC.
I've got two of them working great (yea!), but I can obviously see the need to scale this out since I need like 150 connections (one for each lead of the RGB LED).

I'd like to use PWM, I think, so that my shading of the LED's can be inifinite.

Would someone be willing to suggest a general approach here? I've read about multiplexing, but I'm not sure what that would entail.
Thanks for any pointers.
-Kevin
Logged

USA, FL
Offline Offline
God Member
*****
Karma: 14
Posts: 689
A life? Where can I download one of those?
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Have you tried Google?  Heard it was pretty good at searching for info.

http://playground.arduino.cc/learning/4051


For fading, I would suggest the TLC594x line of drivers.  You can search "Arduino LED driver" on Google. 
Logged

//LiNK

Offline Offline
Newbie
*
Karma: 0
Posts: 5
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for the link.

Maybe next time just skip the attitude.
Logged

SF Bay Area
Offline Offline
Edison Member
*
Karma: 11
Posts: 1244
Arduino Ninja
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Attitude, Google, 150 wires...let's throw all that out.

The main piece missing here is how you want to arrange these LEDs. How bright are they, should they be clusters or single LEDs, how far apart should each pixel be, how bright, etc.

Trying to control 150 wires' worth of PWM is not the best approach here. You need smart pixels, which come in a wide range of types. They will communicate down a single chain of wires using a serial communication protocol. You can actually just buy premade pixel strings with 25 or 50 pixels on a wire, spaced 4" apart. Look for WS2801, WS2811, etc. I also sell LED stuff like the ShiftBrite which is more modular as you chain them together with pluggable cables. The WS2811 strips are also really great because they are really cheap and you can cut them up and rewire as needed.
Logged

Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

Offline Offline
Newbie
*
Karma: 0
Posts: 5
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thank you so much, that is such an awesome & helpful answer!

I'm trying to build something very similar to your hat....I will likely order some strips from you shortly!


The display I'm trying to build is perhaps best described as an excel document:
  • The row is 6 inches tall
  • Each column contains 3 RGB LED's
  • There are 20 columns

So I want to have 20 different parts of the display each be controlled independantly. Does that make sense, and if so would your suggestion of WS2811 still be the way to go? I think I'd have to have 20 different cuts of that material?

Thanks again.
« Last Edit: April 02, 2013, 11:48:36 pm by kevinmcc » Logged

SF Bay Area
Offline Offline
Edison Member
*
Karma: 11
Posts: 1244
Arduino Ninja
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

It depends how far apart you want the columns to be. If you can't use 32mm spacing or 16mm spacing, then the WS2811 strips won't work without a lot of cutting and rewiring (which wouldn't be too bad for only 60 pixels). It'll probably actually be easier to control all the RGB LEDs individually rather than trying to have groups of three controlled together...such is the state of available pixels strings and strips these days.
Logged

Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

Offline Offline
Newbie
*
Karma: 0
Posts: 5
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Awesome thanks, I want to order some WS2811 from you - when will you have them back in stock?
Thanks!
Logged

Valencia, Spain
Offline Offline
Faraday Member
**
Karma: 146
Posts: 5510
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

WS2811 strips are great. You can snip LEDs off with scissors and arrange them any way you want to. The LEDs work out around 50 cents each.

You can control thousands of them with a single Arduino pin, maybe millions (although that would need a fairly beefy power supply).


Logged

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 538
Posts: 27089
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

The WS28xx will have some limit on the number used, the limit being the refresh rate you want to achieve.
For exampe, if you want a 25Hz refresh rate, then the speed you clock the data out plus the 500uS non-clocking time to give the devices a chance to respond to that data will define the limit on the number of parts that can be driven.
25 Hz is 40mS, minus the 0.5mS for device updating (check the data sheet for the particular part), divided by 3 bytes per LED, divided by the data rate used, will yield the number of LEDs that can be supported.

And power, as fungus says: 20mA/LED * 1000 LEDs = 20 amp.
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Valencia, Spain
Offline Offline
Faraday Member
**
Karma: 146
Posts: 5510
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

And power, as fungus says: 20mA/LED * 1000 LEDs = 20 amp.

Actually 60 amps if they're RGB LEDs. smiley

The WS28xx will have some limit on the number used, the limit being the refresh rate

In theory a million LEDs would take about 30 seconds to update.

Anybody got a million LEDs and a 60,000 amp power supply to try it?

« Last Edit: April 03, 2013, 11:43:21 am by fungus » Logged

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 538
Posts: 27089
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

That's more than I want to wire up!
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Colorado
Offline Offline
Edison Member
*
Karma: 47
Posts: 1562
Reviving dead brain cells with Arduinos.
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Awww C'mon CR.  Where's your spirit?  *grin*

Even in strip form, that's 3,333.33 rolls of 5m length (at 60 pixels per meter).  I don't think I'd want to wire up that many either.
Logged

Global Moderator
Boston area, metrowest
Offline Offline
Brattain Member
*****
Karma: 538
Posts: 27089
Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Where would you put it all? Need a roof-like structure like on the Vegas strip or something.
http://www.free-city-guides.com/wp-content/uploads/2010/01/Las-Vegas-Fremonty-Street-Experience-roof.jpg
Logged

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Offline Offline
Sr. Member
****
Karma: 9
Posts: 252
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hey, take a look at this, for sure it will help you, perhaps its not the best solution, but this combined with multiplexing can be what you looking for.





in both cases, you only use 4 pins.
Logged

My 3x3x3 Led Cube

[url=http://arduino.cc/forum/index.php/topic,1642

Offline Offline
Newbie
*
Karma: 0
Posts: 5
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for the videos, very interesting and helpful!
Logged

Pages: [1] 2   Go Up
Jump to: