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Why not control digital LED pixels using DMX?

DMX connectors

Why not control digital LED pixels using DMX?

In my previous blog post you could find the information, why it’s not ideal to use Art-Net to control digital LED strips, LED bars or LED pixels. Now let’s talk about DMX – why is it even more stupid?

Cheap lighting console
Simple lightning console – probably not a best way to control 1000 RGB LED diodes

How is the DMX converted to digital LEDs?

If you want to control digital LEDs using DMX, you need to use one or several DMX to SPI converter (or sometimes called DMX to SPI decoder) devices. SPI means Serial Protocol Interface and the digital LED pixels are usually controlled using this protocol.

DMX to SPI decoder
The DMX to SPI devices are usually ugly 🙂

How many universes do I need for my LED installation?

One DMX universe (or DMX line) sends 512 channels. This Universe can control up to 170 RGB LED diodes (512/3 = 170). If you use typical LED strip with 60 LEDs per meter, you can control up to 2.8m using one universe. What does it mean? Well it means, you have to use additional DMX to SPI controller every 2.8 meters in your installation. And now imagine, you want to use more than 2.8 meters – e.g. to control 100 meters of pixel LED strips – you’ll need at least 35 (!!!) converters/decoders.

Of course, in case you don’t want to display the same content on all your LEDs, you’ll need separate signal output for every one of the decoders. That’s quite a lot even for professional light consoles.

SPI decoders
You usually end up with the stupid complicated schema like this – you need Art-Net to DMX, several SPI decoders and god’s patience

How about huge installations?

Light up the building or TV studio with 1 or more kilometres of LED strips using this old protocol? Oh common!? How much you really want to torture yourself? You’ll get tons of unnecessary cables and tons of unnecessary DMX to SPI boxes around your installation. Crazy…

Huge LED pixel installation
4 kilometres of pixel LED strips – only about 1400 DMX to SPI devices would be needed…

What are the cons of using DMX to control digital LEDs?

  • 170 RGB pixels per one universe
  • Every 170 RGB pixels need separate DMX to SPI decoder (additional cost)
  • Every 3m need separate decoder (additional cost)
  • You’ll need a lot of cables to actually install the controllers
  • In case you want to control the LEDs wirelessly – practically no good solution. There are some wireless DMX products available, but they are not 100% reliable for LED screens.

Are there any pros for this protocol?

Again, it’s compatibility. If you need to control your digital LED pixel installation from standard lightning console like Avolites, MA Grand or ChamSys – especially older versions not supporting Art-Net.

MA Lighting grandMA3 full-size
In case you use “big” lightning consoles, you’ll probably use Art-Net and SPI converters

There is only one good way to use DMX for digital LED pixels – and that’s using this protocol just as a trigger. You can store one or several animations to SD card and play them from device SPI LED controller.

SPI LED controller for digital LED pixels
1024 pixels in one box – replacement for 6 SPI converters

What’s the correct way to control digital LEDs?

Again, we think, the LED Strip Studio is the easiest way to control your LED installation.

Nailing Hammer - not a good tool for complicated installations
If someone will tell you to use DMX512 to control digital LEDs – use this on his head to express your opinion.

But using LED Strip Studio just connect the strips or LED pixels to SPI output of the devices, install the software and you’re ready to impress the audience. No stupid calculations, no unnecessary cables, no problem … just pure fun.

LEC 3 device
The easiest way to use pixel LED strips – LED Ethernet Controller 3