Servo Motor Control

Discussion in 'Chit Chat' started by ceaser, Feb 24, 2009.

  1. ceaser

    ceaser Active Member Licensed User

    I wonder if somebody can help me. :sign0085:

    I want to build a little car which has a GPS and a processor with my software build into it. On the processor I will be able to store the horizontal alignment of the path that the car must follow.

    The software will get the coordinates from the GPS and convert this to a Stake Value and offset from the alignment line. In this way I will always know the distance that the car has travelled and how far away the car is from the alignment line.

    Can I send electric impulses to the RS232 port from my software to control the servo motors, which in turn will turn the wheels of my car so that it stays on track?:confused:

  2. agraham

    agraham Expert Licensed User

    In principle, yes you could drive two servos using the DTR and RTS pins. However if you are considering using the cheap standard RC type servos driven by a Basic4ppc program on a PDA then you will not be able to achieve the accuracy of pulse width required for these servos (1 to 2 mS wide with a resolution of about 5 to 10 uS) to control it properly nor the required frequency either (20 to 30 mS repetition rate) needed to keep the servo alive. You would probably need to interface to a dedicated microcontroller that would control the servos for you.

    I think that you will need the help of an experienced RC model hobbyist to stand a chance of getting anything working.
  3. Cableguy

    Cableguy Expert Licensed User

    Google a bit for RS232 dc motor control and you will find lots of usefull info...
    dc motor are cheaper, and do not need any fancy electronics...Just a opto-isolator circuit to keep the RS232 from fying in the PDA side...
    try the site...lots of info there, like this one..also the ELEKTOR magasine website has a lot of info on this subject...
    Power will be your main concern as motors are NOT power eficient...
    But in a nutshell....YES YOU CAN!!!
    Last edited: Feb 24, 2009
  4. taximania

    taximania Well-Known Member Licensed User

    @Ceaser and have a look round the projects :)

    I've also got servo code for the PIC

    Ir to Pic -> PPC
    Bluetooth to Pic -> PPC
    Serial to Pic -> PPC

    GPS ?, oh yes, use port splitter and a lot of coding on the b4ppc side.

    Been there, done that, and got the t-shirt (English phrase :sign0161:)
    Last edited: Feb 24, 2009
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