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1  Using Arduino / Displays / Re: LCD 16x2 right half won't work on: September 05, 2014, 10:27:48 pm
How is your contrast control hooked up?
2  Using Arduino / LEDs and Multiplexing / Re: Arduino vs DMX with LED lights... Some help needed on: September 05, 2014, 10:11:30 pm
I think you are asking the wrong question.  DMX is just a communication standard initially developed for the entertainment lighting industry (initially theater).  It doesn't control anything directly itself, it's just a way to send messages to receiving devices that then act on that data.  I think what you want is a device that receives DMX and translates that information to control your LEDs.  You could use an Arduino with a DMX shield.  There is some great DMX receiving code at http://www.mathertel.de/Arduino/DMXSerial.aspx.  It is robust, and he also has information about a DMX shield on his site, though you can get those easily on ebay, amazon, or I have even seen them at several Radio Shacks across the country.   I have successfully built several arduino based boards that receive DMX and can output to SPI (to control pwm chips like ws2801 for instance).  The largest I have done so far is 64 rgb leds (3 per rgb led so 192 control channels).  It didn't seem to strain the Arduino, so I'm sure it can be scaled up.  The problem is the tree you reference has 350 RGB LEDs.  Each RGB led needs 3 DMX control channels (one for each color), but you can only have 512 channels on a DMX universe.  So for each group of 512 leds you would need an additional receiver (ie arduino) and a transmitter that is capable of sending multiple universes.  That tree alone would be 26 channels into a third universe.  You could scale it down, but it sounds like you also have to account for other DMX receiving devices on your universe.  In this scenario you would need to take the patterns you want and put them on the transmitting device, which would interpret which light should be on when and send that data via DMX.  I haven't used many computer based lighting programs, but most do have some sort of effects engine that can help to drive some of it, the rest can be done with cue lists or macros.

Another option is to not control the LEDs directly from your DMX source, but to have patterns preprogrammed into your Arduino (or other receiving device) and trigger them with received DMX data, maybe a couple of channels that can signal things like which pattern, speed, overall intensity.  This pattern would be simplest as you would just need to use the code as is, but maybe add a case statement and replace some variables with data received via DMX.

The biggest struggles to be aware of is that DMX is a fairly timing specific protocol, it requires a lot from the interrupts on the Arduino and completely restricts your ability to use the UART for anything else (even debugging) which means you can't simultaneously receive DMX and have output directed to a computer, or really use the USB at all.  It can also be difficult to run complex code because it will be interrupted for every DMX bit received, so difficult calculations may take noticeably longer.  Some implementations of DMX on Arduino can even mess up the accuracy of millis() and micros(), though the code I mentioned above seems to survive this. 

I hope this is helpful information.  DMX is a tricky protocol to DIY, but it can be done with a little patience.  If you have access to a lighting desk like and ETC Ion, Eos, Gio, Ti or GrandMA, or other desk with a built in media server, then you may be able to get the multi universe data you need sent out, though you would still need a new receiver for each 512 addresses.  (You didn't say what kind of live show, is this home use, or professional entertainment industry with access to high end gear). 

If you have any additional information about your desired setup that can help narrow down your specific needs I can give my 2 cents on how it can be implemented.  I have done a number of LED projects in professional theaters in the New York area, as well as for personal projects and am always looking to help solve a new challenge.

David
3  Products / Arduino Due / Re: Dmx library? on: May 19, 2014, 08:36:26 pm
Did you try: http://www.mathertel.de/Arduino/DMXSerial.aspx?

Your post is incredibly vague, so it's hard to tell if this helps.

David
4  Using Arduino / Project Guidance / Re: Controlling multiple RGB LED strips + dmx out on: March 30, 2014, 08:12:15 pm
I'm not a pro with the timers, but I would be surprised if ShiftPWM works with DMX.  I have, however, successfully used DMX libraries with external PWM chips like the ws2801.  Hope that helps.

David
5  Using Arduino / Project Guidance / Re: DMX problem on: February 26, 2014, 06:58:53 pm
I responded to your other post that asked the same question.

David
6  Using Arduino / Project Guidance / Re: Pro mini DMX problem on: February 26, 2014, 06:57:27 pm
Pins 2 and 3 should both be either pulled high, or pulled low, depending on whether you want to transmit or receive.  right now you have told the chip to enable both, which is probably causing logic problems.  In your case it looks like you are trying to transmit, so both pins should be pulled high.  I have also had problems with 485 chips that didn't have a .1uf decoupling cap near them.

David
7  Using Arduino / Project Guidance / Re: LED strip to Midi to DMX USB through Ableton? on: February 25, 2014, 09:04:03 pm
I'm confused about what you are asking for.  Can you describe your setup a little better.

You want the Arduino to receive DMX and send the signal to LED Strips?  Where is the DMX signal come from?  Do you have a DMX dongle on your laptop? 

Do you want to convert Midi to DMX to then drive LEDs?

The strips you specify are great, but they require a range of specific timings from your Arduino, which is possible, but it is unlikely that you will successfully also be able to receive DMX, which requires a speed of 250kbaud.  Maybe there's a software guy on here somewhere that has the know how.
8  Using Arduino / Microcontrollers / Re: bootloading the atmega328-pu on: July 18, 2013, 02:40:12 pm
This method works great for me on arduino 1.0.5, seems to be broken with 1.5.2, though.  Anyone figure it out?
9  Using Arduino / Project Guidance / Re: DMX Controller on: July 15, 2013, 10:52:43 am
I would be happy to help, but I don't understand your question.  Please be more descriptive of what you are trying to accomplish. 
10  Using Arduino / Project Guidance / Re: DMX Hardware issues on: December 14, 2012, 12:58:07 pm
Try pulling pin 2 on your MAX485 Chip high instead of Low.  Right now your chip is enable to receive and drive, which is probably confusing it. 
11  Using Arduino / Project Guidance / Re: DMX Hardware issues on: December 12, 2012, 01:35:59 pm
What rs485 chip are you using?
12  Using Arduino / Project Guidance / Re: DMX Hardware issues on: December 11, 2012, 11:56:06 pm
I had some problems with a DMX circuit I made.  I was using a sn75176 as the RS485 driver and couldn't get it to work reliably without a 0.1uf capacitor tying it's vcc and gnd pins.  Have you tried testing the circuit in a breadboard?  When I first built the circuit on a breadboard I didn't have a problem because of it's inherent capacitance.
13  Using Arduino / Project Guidance / Re: led strip and DMX on: November 08, 2012, 07:32:48 pm
The Toni Merino blog I mentioned earlier has one example that works well with Uno or Mega.

This one: http://arduino.cc/forum/index.php?topic=22294.15;wap2 works well also, but only works on an Atmega168 running Arduino.
14  Using Arduino / Project Guidance / Re: led strip and DMX on: November 07, 2012, 09:15:26 pm
You have to disconnect the rx pin on the Arduino from the MAX485 because the signals from the 485 interfere with the signals from the computer that use the same pin.

Some of the newer DMX libraries don't require changing the HardwareSerial.cpp file.
15  Using Arduino / Project Guidance / Re: led strip and DMX on: November 06, 2012, 11:17:14 pm
The DMX part is easy since you already have the software and the DMX USB Pro.  The software is probably especially helpful in generating patterns, as it means you won't have to program them manually.  Look at either the DMXSimple library or at Toni Merino's blog http://www.deskontrol.net/blog/en/author/toni/.  Toni's code is centered around a mega (though it works fine on an Uno too.)  The extra PWM outputs on the Mega give a little advantage as mentioned by DVDdoug.  Really all you need for a DMX shield is the connector and a MAX485 chip (and I recommend a 0.1uf capacitor).

Probably the most challenging part will be deciding how the DMX channels get to the strips and what will be sourcing all of the current that the strips will need.  Using Mosfets will probably be the best option.

What is your time frame?

Feel free to message me if you have DMX questions.  I have built a few projects using the protocol.
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