How to decide if choose DMX512 or Pixel SPI TTL control system

Date:2022-07-02

How to choose SPI or DMX:

Addressable LED strip categories:  

SPI addressable LED strip
The Serial Peripheral Interface (someone also called : Serial Protocol Interface) (SPI) is a synchronous serial communication interface that connects several SPI micro-controllers. used for short-distance communication, primarily in embedded systems.To send and receive data from the slave or master, requires six wires.

What is DMX512 ?

DMX512 addressable LED strip
DMX512(Digital Multiplex with 512 pieces of information) is a standard for digital communication networks that are widely used to control lighting and create effects. It was originally intended as a standardized method for controlling stage lighting dimmers, which, prior to DMX512, had employed various incompatible proprietary protocols. It quickly became the primary method for linking controllers (such as DMX lighting console) to dimmers and special effects devices such as fog machines and intelligent lights industrial application.

That means continuously transmits the 512 channel values via data cables. 


What's the meaning of DMX address ?

The first thing before we start to light DMX512 led fixtures is to mark address  fixtures, like DMX512 RGBW led strips, DMX512 LED Linear lights.

Because the DMX address is the location of 512 channels where the strips will begin responding to DMX controller.


How to code the DMX address of the DMX512 fixtures, you need confirm the LED fixture channels you got. Like 1 channel(single color),2channels(CCT) 3 channels(RGB) and 4 channels(RGBW). 

We have a simple video to show you how to write the DMX address to DMX LED strips via our DMX adress writer. Contact us freely.


What are the differences between DMX512 and SPI?

DMX512 signal is parallel transmission like parallel circuit;  SPI signal is series transmission.

DMX512 not only have standard RS 485 signal which has double signal wire A,B , but also only single signal wire A which is cheaper than the standard ones;

SPI have single DAT cables like ws2812b ,sk6812. Double signal cables with DAT and Clock are available like SK9822, WS2801;


DMX512 RGBW LED strips connect to DMX controller directly, no need any extra DMX decoders. But SPI pixel led strips connect to DMX controller would need an extra DMX-SPI decoder(signal converter);


What are the advantages of DMX512?

The SPI strips, we normally to run via offline controllers like Arduino, K-1000C controllers or K-8000C controller. 

If we want to play 3D effects via SPI version strips, it is very hard to run by the current software. 


DMX512 RGBW LED strips most advantage is play 3D stage lighting effects.Especailly matrix software.Support MADRIX ,MadMapper,Freesstyler,Resolume,Arena,Arkaos, etc the most popular software systems. 


DMX512 IC chip signal is parallel which could avoid RGB / RGBW LEDs color influenced by the failure of one light in serial connection that SPI IC chips couldn't. 

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Table 1 SPI VS DMX512

 

DMX512

SPI

Signal protocol transmission

Parallel, synchronous parallel interface signal transmission protocol, a universal signal control system for digital lighting equipment

Serial (synchronous serial interface signal transmission communication protocol)

Type Wring

Complicated (Category 5 (Cat5) twisted pair patch cables)

 Easy wiring (JST SM connector female-male)

Compatibility

 Good, unified IC category/protocol, and DMX512 is used for some luminaries

Relatively inferior, with various lC categories and slightly different protocols, basically no SPI luminaries

Quality & Stability

resume from breakpoint transmission, parallel transmission of signals, with high reliability

4 Wire is resume from breakpoint, no renewed transmission of two continuous breakpoints

Anti-interference of signals

Good, with strong long-distance communication anti-interference capability(DMX512 is a bus network no more than 400 metres (1,300 ft) long, with not more than 32 unit loads (individual devices connected) on a single bus. If more than 32 unit loads need to communicate, the network can be expanded across parallel buses using DMX splitters. But actual application 100-200m max better ,with Cat5 STP )

Inferior, long-distance communication is subject to strong current/strong magnetic disturbances(30-50m)

Overall cost

High

Low

Application

Indoor and outdoor large & ultra-large advertisement lighting and synchronous control of stage light show

Small spaces/ independent styling/ supporting facilities


Table 2 - Connection Schedule for DMX512 equipment using IEC 60603-7 8-position modular connectors

Pin (Wire) # Wire Color DMX512 Function
1 white / orange data 1+
2 orange data 1-
3 white / green data 2+ (optional)
6 green data 2- (optional)
4 blue Not assigned
5 white / blue Not assigned
7 white / brown (Common Reference) for Data 1 (0v)
8 brown (Common Reference) for Data 2 (0v)
  drain  


How to convert to spi pixel digital LED to DMX signal?

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.

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)/128 RGBW(512/4). 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.

 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?You’ll get tons of unnecessary cables and tons of unnecessary DMX to SPI boxes around your 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?

l 170 RGB pixels per one universe

l Every 170 RGB pixels need separate DMX to SPI decoder (additional cost)

l Every 3m need separate decoder (additional cost)

l You’ll need a lot of cables to actually install the controllers

l 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 lighting console like Avolites, MA Grand or ChamSys – especially older versions not supporting Art-Net.

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.

1024 pixels in one box – replacement for 6 SPI converters

What DMX512 LED products do we have?

We have many version DMX512 RGBW LED digital tapes from 5V to 24V which density is from 32 leds/m to 120 leds/m. same are the DMX512 RGB LED products.


From our web, you can find our DMX512 RGBW LED strips mainly are double DMX512 signal wire A,B which is RS 485 signal that we mainly choose the UCS512 C4 IC chip to make it. 


But for the 12V addressable DMX512 RGB and 12V addressable DMX512 RGBW LED strips, we use the latest LED package that DMX512 IC chip integrated 5050 package which only has single DMX512 signal wire A. This we called GS8512 DMX RGB LED or GS8512 RGBW LED. 


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.

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


Reference web:
1.wikipedia.org,some already linked to their web.
2.DMX over Cat5 DMX Over Cat5 - Electronic Theatre Controls Inc (etcconnect.com)
3. Why not control digital led strip via dmx Why not control digital LED pixels using DMX? - LED Strip Studio
4.DMX RFQ,if need a 120 Ohm DMX512 Terminator and what kind DMX signal cable should choose ,120 Ohm low-capacitance shielded twisted-pair data cable.  DMX FAQ
5.Why dmx Terminator 120ohm is important ?DMX512 Termination

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