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Thread: E1.31 sACN Ethernet DMX Performance help - 6 Universe Limit improvements?

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    Senior Member crees's Avatar
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    Dec 2016

    E1.31 sACN Ethernet DMX Performance help - 6 Universe Limit improvements?

    Hi Group

    I am working on E1.31 DMX and needs some help getting it fine tuned. I currently have 6 universes working on it but trying to at least double that and more.
    Here is the code so far (sloppy, hacked up, needs improvement, be kind :-)) What I need help with is how to process the ethernet packet buffer better to get all desired universes. In my serial out inside the LED send loop I get 6 universes consistently. anything over is hit or miss. universe 7 is about once per second and 8 is every few seconds.

    I have ethernet set to 1 socket at 24Mhz. I am using the wiz820io .

    // E1.31 Receiver and pixel controller by Andrew Huxtable (
    // This code may be freely distributed and used as you see fit for non-profit
    // purposes and as long as the original author is credited and it remains open
    // source
    #include <SPI.h>
    #include <Ethernet.h>
    #include <EthernetUdp.h>
    #define USE_OCTOWS2811
    // enter desired universe and subnet  (sACN first universe is 1)
    #define DMX_SUBNET 0
    #define DMX_UNIVERSE 1 //**Start** universe
    // Set a different MAC address for each...
    byte mac[] = { 0x74, 0x69, 0x69, 0x2D, 0x30, 0x15 };
    // Uncomment if you want to use static IP
    // ethernet interface ip address
    IPAddress ip(192, 168, 2, 21);  //IP address of ethernet shield
    EthernetUDP Udp;
    // By sacrificing some of the Ethernet receive buffer, we can allocate more to the LED array
    // but this is **technically** slower because 2 packets must be processed for all 240 pixels.
    /// DONT CHANGE unless you know the consequences...
     #define ETHERNET_BUFFER 540 //540
     #define CHANNEL_COUNT 4080 //because it divides by 3 nicely
     #define NUM_LEDS 1360 // can not go higher than this - Runs out of SRAM
     #define NUM_LEDS_PER_STRIP 170
     #define NUM_STRIPS 8
     #define UNIVERSE_COUNT 7
     #define LEDS_PER_UNIVERSE 170
     //#define BRIGHTNESS 100
    // Define the array of leds
    // Pin layouts on the teensy 3:
    // OctoWS2811: 2,14,7,8,6,20,21,5
    unsigned char packetBuffer[ETHERNET_BUFFER];
    unsigned char unidrop[UNIVERSE_COUNT + 1];
    int s = 0;
    void setup() {
        pinMode(9, OUTPUT);
      digitalWrite(9, LOW);   // reset the WIZ820io
       digitalWrite(9, HIGH);   // reset the WIZ820io
      //pinMode(10, OUTPUT);
     // digitalWrite(10, HIGH);  // de-select WIZ820io
      //pinMode(4, OUTPUT);
      //digitalWrite(4, HIGH);   // de-select the SD Card
      // Using different LEDs or colour order? Change here...
      // ********************************************************
      LEDS.addLeds<OCTOWS2811>(leds, NUM_LEDS_PER_STRIP);
      // ********************************************************
      // ********************************************************  
      // ******************************************************** 
        Serial.print("server is at ");
      //Once the Ethernet is initialised, run a test on the LEDs
    void sacnDMXReceived(unsigned char* pbuff, int count) {
      if (count > CHANNEL_COUNT) count = CHANNEL_COUNT;
      byte b = pbuff[113]; //DMX Subnet
      if ( b == DMX_SUBNET) {
        b = pbuff[114];  //DMX Universe
        Serial.println(b );
        if ( b >= DMX_UNIVERSE && b <= DMX_UNIVERSE + UNIVERSE_COUNT ) {
          if ( pbuff[125] == 0 ) {  //start code must be 0
          int ledNumber = (b - DMX_UNIVERSE) * LEDS_PER_UNIVERSE;
           // sACN packets come in seperate RGB but we have to set each led's RGB value together
           // this 'reads ahead' for all 3 colours before moving to the next led.
           for (int i = 126;i < 126+count;i = i + 3){
              byte charValueR = pbuff[i];
              byte charValueG = pbuff[i+1];
              byte charValueB = pbuff[i+2];
              leds[ledNumber] = CRGB(charValueR,charValueG,charValueB);
    int checkACNHeaders(unsigned char* messagein, int messagelength) {
      //Do some VERY basic checks to see if it's an E1.31 packet.
      //Bytes 4 to 12 of an E1.31 Packet contain "ACN-E1.17"
      //Only checking for the A and the 7 in the right places as well as 0x10 as the header.
      //Technically this is outside of spec and could cause problems but its enough checks for us
      //to determine if the packet should be tossed or used.
      //This improves the speed of packet processing as well as reducing the memory overhead.
      //On an Isolated network this should never be a problem....
      if ( messagein[1] == 0x10 && messagein[4] == 0x41 && messagein[12] == 0x37) {   
          int addresscount = (byte) messagein[123] * 256 + (byte) messagein[124]; // number of values plus start code
          return addresscount -1; //Return how many values are in the packet.
      return 0;
    void initTest() //runs at board boot to make sure pixels are working
      LEDS.showColor(CRGB(255, 0, 0)); //turn all pixels on red
       LEDS.showColor(CRGB(0, 255, 0)); //turn all pixels on green
       LEDS.showColor(CRGB(0, 0, 255)); //turn all pixels on blue
       LEDS.showColor(CRGB(0, 0, 0)); //turn all pixels off
    void loop() {
       //Process packets
       int packetSize = Udp.parsePacket(); //Read UDP packet count
       if(packetSize){,ETHERNET_BUFFER); //read UDP packet
        int count = checkACNHeaders(packetBuffer, packetSize);
        if (count) {
         // Serial.println("packet");
          sacnDMXReceived(packetBuffer, count); //process data function
    Last edited by crees; 08-11-2017 at 09:32 AM.

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