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    Originally Posted by gimp
    50/50 I burnt out a chip soldering (no IC holders and one got really hot - oops) or I just did something else wrong.
    There are so many ways to screw up. Did you use clip on heat sinks to keep the chip cool during soldering? Sometimes they make a difference.
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    Nope. The chips are supposed to have two bridged connections as heat sinks, and it was probably holding the heat there too long to bridge them that did it. I'm gonna desolder to see if it helps but it probably won't.

    Edit: Tard tard tard, forgot to put on the jumper onto the two power pins in the bottom center. Board should work fine. No motors to test it yet though.

    XBees work a charm. Writing protocol now. It'll have a start of command, end of command, and pairs of bytes between them. The first in the pair of bytes identifies a motor, the second says what power. The first bit will identify direction the same way that the first bit of an int identifies negative or positive.
    Last edited by gimp; November 8th, 2009 at 04:44 PM.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
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    Well, the protocol works well.

    The issue that I for some reason failed to foresee is the need for a) waterproof motors, and b) gearboxes. I'll do my testing on-land (most likely) with a nice motor I have, but for water testing there's almost no chance to keep them entirely dry.

    Furthermore, gonna need to find an container to house electronics that is A) waterproof and B) allows for radio communication (wireless, 2.4 ghz.) I'm thinking some sort of fiberglass box with rubber seals should do the trick. Getting wires in and out will again be tricky, I'll figure it out when I get there (thankfully I know a few mechanical engineers.)

    Gonna ask a professor where to get - if possible - waterproof transducers. We get to play with them in the lab (1 mhz, if I remember correctly) and I'm hoping they're cheap. Of course, that's for later.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Got joysticks. They don't go into a breadboard. Going to design my own circuit board and make it with the help of google's many results on how to make a circuit board.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Avoid the many proto-board sites that let you design your board either using their software that you download or their web based design tool. They are just trying to lock you into using their services. There are good proto-board companies out there that accept the standard files that the various tools (such as Eagle) are capable of generating and they have competitive prices.
    I no longer wish to be associated with this site.
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    Originally Posted by jwdonahue
    There are good proto-board companies out there that accept the standard files that the various tools (such as Eagle) are capable of generating and they have competitive prices.
    Aren't gerber files the defacto standard? and I've yet to see a layout tool that can't make them.

    When you get more serious, the better packages have design rules that can check your layout, i.e. keeping traces X mm apart or Y mm from the edge of the board.
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    Eagle + Printer + Chemicals + Copper plate = cheap way a broke college kid can make his own. I won't be ordering from any site.

    (Though I do wish I had a way to silk-screen.)
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Two-complement is a better representation than magnitude, in my opinion. I'll be changing my code accordingly.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Originally Posted by gimp
    Two-complement is a better representation than magnitude, in my opinion. I'll be changing my code accordingly.
    That was argued heavily in the 50s, and perhaps into the 60s. Two-complement won.

    I think in part because it made the adder logic so easy.
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    Yep. Also I didn't like having two values for zero the way I was doing it -- two-complement avoids that issue.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Its Spring, March winds to fill a sail


    So how is progress? Depending on where you are, Spring and Fall usually have the most wind and warm enough temps that you can go outside and play with the boat.

    Around here, in Summer, its very hot and no wind, so sailboats are no fun. Toy size or full size
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    Fun story: My friend burnt out his only arduino about a few days before his project was due, so he has them at the moment.

    I've been reconsidering some hardware, architecture, and tool choices in light of what I know now.

    Namely:

    Arduino megas are $50. PIC 16F722 is $2.50 or so. PIC has fewer ports, but it has enough to control eight motors (16 IO), an xbee (2 IO, USART) and still have 7 ports left over for other peripherals (compass, depth-detector, wind direction?). On the remote control side, it has 11 A/D converters (only 8 needed to control 8 motors), USART, and ... really don't need anything else yet, but maybe a few buttons, LEDs, a cheap LCD.

    Next, a motor controller needs to be built; using a 'shield' from a kit is no good (need 8 channels, not 4, and need it to handle maybe as much as 2 amps) and buying a professional one is far too expensive (I only need some heavy duty H-bridges).

    I also need to build a boat. Boats the right size that can float and are waterproof are hand-made models and are about as expensive as a real (small, second-hand) sailboat. No idea how to do that.



    I'm slowly getting there, realizing every step of the way that something should be done differently. Those classes are teaching me something, yessiree.



    Once I have time to do it actively again, I'll start by making a motor controller. Really nothing fancy, just four relatively high power transistors per channel with maybe a small (electrolytic, 10 uF?) cap across the motor leads to smooth the signal.

    Can you recommend the transistor? I'm thinking a cheap MOSFET that can handle around 2-5A at somewhere up to probably 50 V (won't be using as much, probably 9, 18, or 27 V). That times 32 (4 per channel).
    Last edited by gimp; March 31st, 2010 at 10:41 PM.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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    Arduinos are cool because they come ready to go, plug in, write a bit of code, and you are cooking. But you are right, there are much cheaper approaches if you are willing to do more work. Both PIC and TI MSP430 have versions that are much cheaper and well suited for this stuff. But the arduino is ready to go, no soldering or mask layout needed.

    "5A at somewhere up to probably 50 V" is a ton, that's 250 watts. Proper support for that will not be easy.

    Also, you need to include some caps in the circuit to absorb the electricity generated by the motors as they coast to a stop when you turn off the power. It can be a fair amount, and will burn out chips if you don't plan for it.

    Yeah, model boats are not cheap if you want them to actually float, not leak, have a keel with weight to keep the sail up in the wind.
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    Yeah, I doubt I'll need more than 2A at 27V, but MOSFETs seem to be able to handle such things without much of an issue.

    I did indeed forget about the need to store the back EMF generated. I'll look into it - start with breadboarding a single channel for a relatively big motor and go from there.
    Last edited by gimp; April 1st, 2010 at 10:26 PM.
    Chat Server Project & Tutorial | WiFi-remote-control sailboat (building) | Joke Thread
    “Rational thinkers deplore the excesses of democracy; it abuses the individual and elevates the mob. The death of Socrates was its finest fruit.”
    Use XXX in a comment to flag something that is bogus but works. Use FIXME to flag something that is bogus and broken. Use TODO to leave yourself reminders. Calling a program finished before all these points are checked off is lazy.
    -Partial Credit: Sun

    If I ask you to redescribe your problem, it's because when you describe issues in detail, you often get a *click* and you suddenly know the solutions.
    Ches Koblents
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