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Thread: Lasershark, a completely open-source low cost dual-laser 12bit USB laser DAC

  1. #21
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    Apr 2010
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    San Francisco
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    204

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    Slick!

    Seconding mixedgas's "more outputs" suggestion. You've got tons of spare GPIOs on that micro; just route all of them to pin headers. (Bummer that the LPC1343 only has one UART...)

    The first DIY DAC that I built had some very basic onboard constant-current drivers built in, which was super handy for reducing overall number of parts in the projector. A dumb low-side CCS doesn't take much in the way of parts - just a BJT, opamp, and some resistors. Flexmods are nicer, but something homebrew will get the job done in a pinch.

    edit: also, making the UART header pinout-compatible with these things https://www.sparkfun.com/products/9718 makes software debug super easy.

  2. #22
    Join Date
    Apr 2012
    Location
    Baltimore, MD
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    Quote Originally Posted by j4cbo View Post
    Slick!

    Seconding mixedgas's "more outputs" suggestion. You've got tons of spare GPIOs on that micro; just route all of them to pin headers. (Bummer that the LPC1343 only has one UART...)

    The first DIY DAC that I built had some very basic onboard constant-current drivers built in, which was super handy for reducing overall number of parts in the projector. A dumb low-side CCS doesn't take much in the way of parts - just a BJT, opamp, and some resistors. Flexmods are nicer, but something homebrew will get the job done in a pinch.

    edit: also, making the UART header pinout-compatible with these things https://www.sparkfun.com/products/9718 makes software debug super easy.
    For cost reasons (making the board bigger = more expensive, adding more components = more money) I don't think I'll be adding the laser drivers. I'm thinking these should be a separate part anyhow for a better modularized design since the current requirements of lasers can vary (Althought hopefully you aren't driving a 15W laser with these.. I think a system with more redundancy would be a good idea there, heh)

    I will try breaking out the GPIO pins and will definitely try making the uart header compatible with a FTDI cable (if space allows).. good suggestion.

    " just route all of them to pin headers. " is way easier said than done. Due to the frequencies of the DAC (36Mhz) and USB I wanted to keep these components as close to the lpc as possible. This makes breaking out all the pins more of a pain since this is a 2-layer board. I will break out what I can.. but they won't be in headers... that's they type of stuff I'm going to leave to the Lasershark Pro board.

    Thanks for your thoughts

  3. #23
    Join Date
    Apr 2012
    Location
    Baltimore, MD
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    Here's the updated board:
    This version is the same size and has all the features of the old one but now adds:
    -Option for the following modes:
    --3 TTL channel laser outputs
    --1 analog channel laser output
    --2 analog channel laser outputs

    -Interlock output
    -Interlock input (over-voltage protection present)
    -Expanded uart pins to support a ftdi breakout cable
    -Added gnd pin to spi and uart header pin spots
    -Added header pin area to break out 5v, 3.3v, and gnd.

    I purchased enough parts to make 9 of these boards if anyone is interested in one.

    All in all, the changes were easy to make. There is one issue with the C channel and INTL A output channel and that is that they output 10v for an extremely brief moment when the uC starts up and continuously when it is in programming mode. The other channels do not suffer from this. This is caused by the uC's pins being set to pulled up inputs at startup which is something that unfortunately is out of my control.


    Last edited by macpod; 12-17-2012 at 21:40.

  4. #24
    Join Date
    Sep 2012
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    64

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    I would be interested. How much shipped to me in NY? I have some galvos that are begging to be played with. By any chance is this board compatable with xy2-100 protocol for engraving?
    Thanks!!

  5. #25
    Join Date
    Apr 2012
    Location
    Baltimore, MD
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    69

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    Quote Originally Posted by als1980 View Post
    I would be interested. How much shipped to me in NY? I have some galvos that are begging to be played with. By any chance is this board compatable with xy2-100 protocol for engraving?
    Thanks!!
    Pardon the slow reply, the holidays have kept me busy.

    I have no experience with the xy2-100 protocol so I cannot say. I'm building these by hand which is pretty boring so I would like to get 65$ shipped for a V2 board. This also helps cover costs of newer board that I will be making

    Please be aware this is only going to work with OpenLase for now unless you want to get down and dirty and write your own drivers.

    I've got unpopulated V1 boards too around here too. If you want one of those to solder together yourself 5$ should cover that.

  6. #26
    Join Date
    Sep 2012
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    Deal. Ill take one. Let me know how to pay you the $65 for a v2. Thanks!!

  7. #27
    Join Date
    Apr 2012
    Location
    Baltimore, MD
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    I can accept payments via paypal (nelsonjm@macpod.net).

    I wrote some docs on how to setup OpenLase here:
    https://github.com/marcan/openlase/wiki

    I would suggest using my repo as I haven't had a chance to push my changes back to the original Openlase project:
    https://github.com/macpod/openlase

    I still need to write the LaserShark setup docs.. It's pretty easy to setup and that will come soon.. just have lots of other stuff I need to do.


    Also, I have a mailing list:
    http://macpod.net/mailman/listinfo/l...ark_macpod.net

  8. #28
    Join Date
    Sep 2012
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    64

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    Paid. I will look into all you have written and let you know how setup goes! Thanks again!

  9. #29
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    Apr 2012
    Location
    Baltimore, MD
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    Got it, thank you. I'll solder and tune that tomorrow then drop it in the mail Thursday

  10. #30
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    Sep 2012
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    64

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    Sounds good! Cant wait for it to come!

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