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Newbie - Minimum necessary to control RC servo & 1 relay

Discussion in 'Electronic Basics' started by BR, Sep 10, 2004.

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  1. BR

    BR Guest

    Hello,

    What is the minimum necessary to receive and decode IR serial data
    from PC serial port, and then control an RC servo and 1 relay?
    Quickbasic is used to send data. I just started looking into
    microcontrollers but haven't purchased one yet. Parallax starter kit
    looks attractive but seems rather pricey for what I want to
    accomplish.

    Ben

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  2. Si Ballenger

    Si Ballenger Guest

    You may want to check the comp.robotics.misc news groups for
    similar setups. I don't understand how you are sending IR through
    a serial port, but a simple way to control servos from a computer
    via the serial port is to use a programmed servo control chip. At
    the link below I show how I use the ezservo chip from kronos
    robotics ($6.95) to control servos that operate a pan and tilt
    webcam. The bottom link shows a workaround I made to control some
    LEDs using the servo control output lines from the chip. This
    could control a relay if desired.

    http://www.geocities.com/zoomkat/ezservo.htm
    http://www.geocities.com/zoomkat/ezservo1.htm
    http://www.geocities.com/zoomkat/ezservo-led.htm
     
  3. BR

    BR Guest

    shb*NO*SPAM*@comporium.net (Si Ballenger) wrote in
    I meant a PC serial port connected to an IR transmitter.
    Thanks. That is just what I was looking for. I thought there'd be a
    chip for that app.

    Where's the circuit that converts a servo output to an on-off output?

    Ben

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  4. Si Ballenger

    Si Ballenger Guest

    For the LED I put a diode and a 1k resistor in series from a
    servo output pin to the base of an NPN transistor. Between the
    diode and the resistor, I put a .1mf capacitor connected to
    ground. There are sufficient pulses for the servo (chip set for
    its longest pulse lenth on the pin) to charge up the capicator
    and supply a ~steady current to the transistor base. The LED is
    connected to a power supply and is in series with the transistor
    collector/emitter. A driver chip that needs less current to turn
    on might work better than just a NPN transistor in this setup.
    YMMV.
     
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