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A DMX Forest — Parallax Forums

A DMX Forest

spinefan03spinefan03 Posts: 10
edited 2014-01-29 20:32 in Robotics
Hello everyone.

I have a project that involves DMX controlled trees...

Architectural style lighting of a wooded area, where each tree has a dmx address. Planning to include as upgrades, more led fixtures, additional trees, and wireless touchscreen DMX output device. I will only be using spin. (took too long to learn one language... sight of anything else could make my head explode at this moment.)

I have the general overall idea of how it will be designed, but a couple of things I could use some advice. I have a few years experience tinkering with spin with a handful of proto boards laying around the house. I have built a few projects that are installed in clubs throughout the area, all using modified versions of the available dmx objects. I also work as a system engineer and lighting designer for concerts and events. And I have access to a machine shop through work I do part time as a bronze sculptor. .. I need another project.



PWM Output

USB Project Board sending PWM signal to various led fixtures on the trees. (Large LED Cans at the base, small "limb" LEDs, strobes, etc) Each tree with a separate DMX address and power distribution board for LEDs.

I have not yet tested the number of PWM signals I can send. Only a few pins are needed for the USB and DMX. Is the number of pins capable of sending a PWM signal limited, or is it only limited by the number of pins available?

LED Power

There will be a variety of LEDs used for each Propeller unit, requiring different power. My original plan was to design using the basic current limiting circuit for each LED (easy to "modify" for each power requirement) I am under the assumption this circuit can be switched fast enough to be used with PWM? ... As there will be a couple hundred different LED channels to power, this would require hundreds of tiny four piece circuits I would have to build between the LED and and the line voltage. Adds a couple hundred bucks as well.

What I would like to do instead for power, is to send 5 or 6 separate lines, with fixed currents, from a central power station and throughout the complex of units. I am just starting to look into what is needed to build this current regulated power supply, but wanted to take a moment for some much needed device before I dive in the whole project. Will I be able to make regulated current, capable of being used for PWM, by varying amounts of lights? (a handful of lights may be using the 700ma line while another group of lights starts to PWM using the same 700ma power source)


Thanks for reading all of that, if anyone did. I have later plans for this project, including a touchscreen for control and wireless LED units using xBees, hopefully by summer. Will be using USB-DMX until then. Also thinking of adding some servos for some wiggling lights. (depending on how many pins I can PWM with) Hopefully I can contribute to this community that I have taken so much knowledge from. Planning to have schematics up within the week. Plans.

Comments

  • kwinnkwinn Posts: 8,697
    edited 2014-01-26 20:57
    spinefan03 wrote: »

    PWM Output

    USB Project Board sending PWM signal to various led fixtures on the trees. (Large LED Cans at the base, small "limb" LEDs, strobes, etc) Each tree with a separate DMX address and power distribution board for LEDs.

    I have not yet tested the number of PWM signals I can send. Only a few pins are needed for the USB and DMX. Is the number of pins capable of sending a PWM signal limited, or is it only limited by the number of pins available?
    Prop PWM is only limited by the number of available pins.
    LED Power

    There will be a variety of LEDs used for each Propeller unit, requiring different power. My original plan was to design using the basic current limiting circuit for each LED (easy to "modify" for each power requirement) I am under the assumption this circuit can be switched fast enough to be used with PWM? ... As there will be a couple hundred different LED channels to power, this would require hundreds of tiny four piece circuits I would have to build between the LED and and the line voltage. Adds a couple hundred bucks as well.

    What I would like to do instead for power, is to send 5 or 6 separate lines, with fixed currents, from a central power station and throughout the complex of units. I am just starting to look into what is needed to build this current regulated power supply, but wanted to take a moment for some much needed device before I dive in the whole project. Will I be able to make regulated current, capable of being used for PWM, by varying amounts of lights? (a handful of lights may be using the 700ma line while another group of lights starts to PWM using the same 700ma power source)

    I'm not quite sure I understand what you are asking here, but building a constant current or variable current controlled power supply can be done, and it can be switched on/off fast enough for PWM.

    Sharing that supply is another matter. The current can be split between two or more circuits, but you will need some circuit to control how much current goes to each branch unless you are going to multiplex the entire current between the branches.

    Perhaps you can post a simple diagram to clarify what you want to do.
  • spinefan03spinefan03 Posts: 10
    edited 2014-01-28 07:04
    Thank you. With those couple of questions answered on PWM, I can continue on with the software design. As for power, after comparing different methods of getting power to the LEDs, I found the cheapest and most logical choice for me being a common pc psu. This will also give me greater flexibility in led selection, as each led string will have its own current limited supply. I will post more info once I work out a few small details. I have found a way to include in this build a device that I have been designing for years. A client has been found to finance this venture, removing the only previous barrier to completing this project. Looking forward to sharing my work with others, and aware that I wouldn't be able to do it without people like you. Thanks again.
  • Shawn LoweShawn Lowe Posts: 635
    edited 2014-01-29 07:41
    Check out www.efx-tek.com they have a hc-8 board that should do everything you want. Jon mcphalen is Co owner (jonnymac in these forums) and he would have no problem helping you if you need it. Excellent customer s service
  • spinefan03spinefan03 Posts: 10
    edited 2014-01-29 20:32
    The HC-8+ board would be a great drop in solution for many of my projects. I am building a modular setup with ribbon connectors to simplify certain build phases though, and would require modifying the existing code and hardware. Using the HC-8+ for a single 24 channel tree could could raise the price from $100 to $500 for electronics, not reasonable for a forrest. Thanks for the link though, I am finding many things on that site that I "need."
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