Standalone DMX Recorder/Player devices

Discussion in 'The Development Lab' started by riri7707, May 29, 2010.

  1. riri7707

    riri7707 Full Time Elf

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    Hi,
    I have some thoughts about the availability of such device:
    Just simply prepare your shows on your PC or laptop, record them on a DMX recorder, then playback on demand
    without the needs of computer, just as a standalone device.

    I found in the market such devices ( for lightshows party), but very limited; not enough fixtures, steps, limited DMX channels and poor timming on lenghts of the sequences. (between $100/$200).
    I didn't invest yet on that, as i don't found something really relevant four our light word.

    The best will be to have one controller with scheduler, internal card reader, 512 DMX channels, external synch triggers, etc...

    I assume this kind of DMX Recorder/Playback can be a master piece to add to DIY lights, for those who don't want to always have a leg attached to the computer, prevent from freeze, computer crash during the show, power failure, etc...

    Your thoughts are welcome...

    Cheers, Henri
     
  2. AussiePhil

    AussiePhil Dedicated Elf Administrator

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    Henri

    This is the direction RJ is going with the Lynx Conductor I think, i have looked at the whole record DMX to external storage and put it on the desirable but not high on the list.
    I'm waiting to see just how fast channel counts rise with the move to RGB and the then corresponding pain of dealing with 1000's of channels in one device.

    Cheers
    Phil
     
  3. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    I would agree, with the high channels counts and RGB somthing like this would be better to wait to see where the new lighting technology is going. Dont want somthing that will obsalete in a year.
     
  4. OP
    OP
    riri7707

    riri7707 Full Time Elf

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    Thanks Phil,

    I know this is something RJ have in his project basket...

    I'm just curious to know if some members have some experience on that or had try such existing devices.

    RJ have so much tasks today specially with Aether, i don't think we will have something this year.
    This is a very complex development from my point of view.

    So let's cross the fingers and make a little pray and light some (led) candles...

    Have a good day...

    Cheers, Henri
     
  5. David_AVD

    David_AVD Good news, everyone!

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    I've been thinking of designing a small DMX playback unit myself. I did start a thread on DIYC, but now that I've joined this forum I might as well contribute if I can!
     
  6. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    David you are very welcome to contribute and do a design on this, im sure you will have plenty of guys give you assistance if you need it. Welcome to the auschristmaslighting forums and we hope that you find us helpful. All the best with your design.
     
  7. David_AVD

    David_AVD Good news, everyone!

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    My main concern is the time taken to write to an eeprom so I checked out some cheap (~ $2) 256Kb SPI sram from microchip.

    It offers byte mode (set address each time), page mode (set address once to read a whole page), as well as sequential (set address and then clock data out continuously). The sequential mode sounds perfect for easy recording (write) and playback (read).

    Each DMX channel byte is only 44us long, so plenty of time to fetch the next byte (via SPI) from the sram during the UART's transmission of the current byte. The same timing would apply to reading from an SPI eeprom of course. The only bottleneck would writing to the eeprom.

    I suppose you could write data from the incoming stream (during the learn phase) to sram, then copy to eeprom afterwards. That gets us back to non-volatile storage and away from a battery backed solution.
     
  8. AussiePhil

    AussiePhil Dedicated Elf Administrator

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    David

    now if you could design this around the 24FC1025 1Mb as used on the tiger controllers.............................
    This device has both byte write and page write capability of up to 128 bytes of data.
    It's a Fast mode device that should be fully capable of writing a DMX capture in real time. you know i want to test this now :)

    Whatever way you go to make this work will be fantastic and i'll take one for my garden lights please.

    Cheers
    Phil
     
  9. David_AVD

    David_AVD Good news, everyone!

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    I must admit I didn't consider that page mode writing could be so quick. In my day to day programming I mostly use the internal EE, which is limited to writing one byte per 4-8ms on the 16Fx series.

    Using a 1Mb device in page mode, writing 4 datasets of 32 channels every 200ms (50ms resolution) would capture nearly 3.5 minutes of stream.

    Even the common (and cheap) 16F88 we use has enough ram to buffer each page. Actually, since you should be able to pause the page loading (I2C clock) between samples, I guess there's no real need to buffer it anyway.

    The only benefit I can see with buffering the data is you can throw away a bad frame if required. You could even re-use the last frame (to maintain the timing) if you really wanted.
     
  10. ron

    ron Apprentice Elf

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    Wow, 3.5 minutes would be plenty for capturing some base programs. Plenty for a garden light type setup. I like it, very interesting.

    Ron
     
  11. David_AVD

    David_AVD Good news, everyone!

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    I'm doing the board design for this today as I'm getting a PCB panel done this week.

    Due to my current workload I may not get a chance to write the code and build the prototype for a few weeks.
     
  12. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Im interested in this project, im just wondering have you considered an input trigger so it can be used all year around with a motion sensor for landscape lighting. Just a thought.
     
  13. David_AVD

    David_AVD Good news, everyone!

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    Yes, I will be including a contact trigger input.

    It will use mainly SMD components and have an ICSP connector for programming the micro.

    Thinking of having separate DMX input and output chips. That way it could act as a backup in case of incoming DMX failure.

    Not sure what else. I'm making it up as I go along. Can you tell? :D
     
  14. David_AVD

    David_AVD Good news, everyone!

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    OK, layout is done. It has not been prototyped or tested in any way. Hopefully there are no gross errors!

    The board is 38.1mm (1.5") x 50.8mm (2"), double sided and uses all SMD parts except for the connectors. There is a 3mm mounting hole in each corner.

    There are separate DMX input (with termination resistor) and DMX output chips. As noted above, firmware could be written that passes live DMX data through, but reverts to the (previously) stored sequence upon loss of DMX input.

    There is a 12V DC input with reverse polarity protection, on-board LEDs for record and play, as well as a connector for the record and play buttons / contacts.
     
  15. David_AVD

    David_AVD Good news, everyone!

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    Here's what the board looks like.

    [​IMG]
     

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