{"id":681,"date":"2012-06-11T06:25:28","date_gmt":"2012-06-11T06:25:28","guid":{"rendered":"http:\/\/baulkolites.com\/wp\/?p=681"},"modified":"2014-02-28T20:53:04","modified_gmt":"2014-02-28T20:53:04","slug":"dmx-start-address","status":"publish","type":"post","link":"http:\/\/mynoellights.com\/blog\/?p=681","title":{"rendered":"DMX Start Address"},"content":{"rendered":"

All my controllers and most other DMX controllers used in the Christmas Lights hobby don’t use switches to set the start address like most commercial applications.\u00a0 As far as I can see, there are two main reasons for this:<\/p>\n

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  1. Our controllers are not moved around an lot, where you need to be able to set the address regularly<\/li>\n
  2. we want to economise on space.<\/li>\n<\/ol>\n

    Removal of the switches does require another mechanism to set the start address.\u00a0 the least cost option is to use Vixen.\u00a0 Create a simple 2 second sequence and use the first 2 or 3 channels to transmit a known level as required by the particular controller.\u00a0 Just remember to set Vixen to absolute levels and the sequence\u00a0 to repetitive.\u00a0 I have used the method for a couple of years.<\/p>\n

    I also have\u00a0 a neat test set featured in Elektor’s June 2002 Portable DMX Tester<\/a>.\u00a0 This unit not only displays the DMX Received but also transmit values input through the GUI.<\/p>\n

    This year I am added a fair number of controllers as well as changing the display around.\u00a0 To enable fast Stat address resetting I created my TinyTxDMX testset.\u00a0 It doesn’t have any bells and whistles, it can’t RX DMX, it can’t tell you anything cause it doesn’t even have a LCD display.\u00a0 But it is small, small enough to fit in your pocket and reliable.<\/p>\n

    \"\"<\/a>

    TinyTxDMX Test Set<\/p><\/div>\n

     <\/p>\n

    As can be seen, there isn’t much to this.<\/p>\n

    X1 is an RJ45 and outputs DMX data.<\/p>\n

    S1, S2 & S3 are Binary Coded Decimal switches that are used to set the Start address<\/p>\n

    S4 is a push button switch to wake it back up.<\/p>\n

    H1 is a LED that flashes every second\u00a0 to show it it awake.<\/p>\n

    X3 is used to change the start address scheme.<\/p>\n

     <\/p>\n

     <\/p>\n

    Update1 – July 2012<\/strong><\/em><\/h3>\n

    The PCBs came back from the Fab House.<\/p>\n

    Zero defects found – I still get a warm and fuzzy feeling with I find out I did it all right.<\/p>\n

    \"\"<\/a>

    First Prototype soldered<\/p><\/div>\n

    Rev 1 of the firmware is loaded and works a treat.<\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

     <\/p>\n

    DMX Tx Firmware<\/em><\/h3>\n

    Henne’s Tx code<\/h4>\n

    The transmission code is completely based on Hendrik Holscher ‘s code found in ApNote 113.<\/p>\n

    http:\/\/www.hoelscher-hi.de\/hendrik\/english\/ressources.htm<\/p>\n

    What is interesting about Henns code is the use of multiple baud rates to build up the DMX protocol.\u00a0 A breif description follows:<\/p>\n

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    1. The Break portion – set Baud rate to 90.9K baud<\/li>\n
    2. StartByte – set Baud rate to 250K baud<\/li>\n
    3. Delay by IBG uS<\/li>\n
    4. start transmitting the data at Baud rate of 250K baud<\/li>\n<\/ol>\n

      Start Address Schemes<\/h4>\n

      Two start address schemes are implements.<\/p>\n

      Add Ch1 and Ch2<\/h5>\n

      For start address 1 to 255<\/p>\n

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