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RE: [SeattleRobotics] little networks - [Re: The Wozniak Test

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  • Alan Marconett
    Dan, Can your MSCC20 multi-servo controller chip do group or coordinated moves? That s something that seems to come up often with walking bots. I ve been
    Message 1 of 321 , Dec 2, 2009
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      Dan,

      Can your MSCC20 multi-servo controller chip do "group" or coordinated moves?
      That's something that seems to come up often with walking 'bots. I've been
      reading through your servo commands (quite a few!), but didn't spot it.

      Alan KM6VV

      > -----Original Message-----
      > oric_dan
      >
      > Hmmm, my servo controller chip is a 16F877, and can run up to 20 servos
      > with velocity control [and even acceleration control on some versions],
      > and with minimal use of code space. I used the compare modules and
      > interrupts, and overall duty cycle is circa 5-10%.
      >
      > This left me so much code space and duty cycle available that I
      > implemented my complete walking machine CPG gait generator on the same
      > chip, along with FSM logic that could read sensor input, and branch
      > between different gaits [up to 126 gaits stored in eeprom], for automatic
      > turning, backing up, etc.
      >
      > I used it on my hexapod Nico-6, along with a BS2 for general
      > programmibility. I coded the BS2 with a bunch of routines to read sonars,
      > command the CPG chip via RS232, and to run the Robothon walker contest.
      > The BS2 was just barely able to handle the job, but the 16F877 had no
      > trouble.
      >
    • Randy M. Dumse
      oric_dan said: Wednesday, December 02, 2009 12:12 PM ... Hi Dan, I really don t think USB to micros is the way to go. I think CAN is a much better approach. A
      Message 321 of 321 , Dec 13, 2009
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        oric_dan said: Wednesday, December 02, 2009 12:12 PM
        > The netbook becomes the high-level brains, plus useful
        > for wifi comms, of course.

        Hi Dan,

        I really don't think USB to micros is the way to go. I think CAN
        is a much better approach. A webpage, or spreadsheet, of
        features would probably be a good thing done. I'm not sure I can
        do it. But here's a first blush. I would like a network that was
        muyltidrop, peer-to-peer, availble on small micros.

        CAN Ser SPI I2C USB Ethernet
        Small Sys x x x x
        Multidrop x x x x
        PeertoPeer x x
        CSMA/CA/CD x x
        Noise Immun x x
        Video x x


        So CAN is favorable for everything important except video (also
        not all small micros have it, but SPI peripherals can
        compensate). Ethernet is suitable for everything except
        reasonaly small micros we'd really like to use. USB misses on
        almost all desireable traits except video (but that solves
        webcam issues). It requires a host (master-slave) arrangement.
        It is not suitable for small systems (particularly the hosting),
        and it takes hardware and software at every micro to talk. It is
        not multidrop, so every node has to have a hardware channel to
        host or hub.

        (My experience with this was seeing it in action on the Smart
        Car CAN Bus, where many controller units offered up their
        reports on the bus, and anything in the car that needed that
        information could just grab it when it came by. For instance,
        both the throttle and the transmission could watch where the
        operator put the gear selection and the pedal. The front panel
        could read the engine water temperature and know if it should
        set a warning. Nobody asked for data. It was always there,
        updated at the necessary rate, depending on expected latency
        levels.)

        So I'd think your best solution is from your netbook use one USB
        for Webcam, and one USB as a bridge to CAN or something like
        that.

        Randy
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