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SV-100[B/C]-200[B/C]-203[B/C] FAQ
Table of Contents

  • Introduction

    • Status

      This FAQ is maintained by Jacob Christ.Please send all inquiries regarding this FAQ to jacob@pontech.com

    • What is the SV100[B/C] ?

      The SV100 is the original product that started it all. Allowing for control of 4 PWM (Pulse Width Modulated) servos via a serial connection to a personal computer. Soon after the imitations appeared.

      The SV100B is a SV100 that has an onboard BASIC byte code interpreter to allow for a BASIC program to be downloaded and run in an autonomous fashion.

      The SV100C is a SV100B with an added board to allow for receiving IR signals from a SONY TV remote (or universal equivalent).

    • My SV203 seems to have slightly different servo positions than my SV200/SV100, why?

      Timing. The SV203 uses the more current de facto standard. If you prefer the older de facto standard, request it at the time of ordering.

    • Message Board

      Thanks to PONTECH customer Steve Arnold the SV203 now has a message board for us all to discuss SV203 related issues in a public arena. Thanks Steve.http://groups.yahoo.com/group/Pontech_SV203/

  • Power

  • Connections

    • What is the purpose for J4 (5V)? -Chikyung Won

      Just an optional power connector. Often people will solder a 100uF cap in this location to provide cleaner 5V source when using the A/D converters on the board.

      PONTECH now ships all SV203 board with a capacitor in this connector. July 18, 2002

    • What is the purpose of "IN1" and "IN2"? -Chikyung Won

      That's a secret. Just kidding. We have done some custom firmware for other customers that used these inputs.Currently they have no function on the SV203.

  • Motors

    • Servos

      • What servos will work with the SVxxx[B/C]?

        The SV line was designed primarily for servos with FATUBA J-type connectors. Other servos will work but often need to be modified (re-wired) to work properly with the SV boards.

    • We are experimenting with a MPI MX-400 servos modified for full rotation.

      This is our first experimentation, and when we send the board a command to run a motor to a certain point, it will spin continuously. If we supply values between 1 and ~134, the motors operate clockwise, slowing down as we supply near numbers near 134. If we go substantially over that, the motor will reverse, and go in the opposite direction, with speed maxing out at 255. Our latest idea is that this continuous motion must be a factor of the modification. In any case, we're confused. If you could shed some light on this, it would be helpful.

      Thanks,

      Tom Nichol.,
      Jeff Powers,
      Tony Magri

      The way a servo works is there is a position pot inside that lets the internal electronics of the servo know it's current position. When a command is sent (1-255) it tell the servo which position to go to. When the electronics inside the servo detects it is getting close to that position it begins slowing down the motor. When it arrives at that position it stops the motor. A servo that has been modified for continuous motion has the position detector disabled and set so that the onboard electronics thinks the servos is always at some fixed position (approximately center, let's say position 128). When you give a command to go to position 1, the electronics on board the servo detects that it is at the center position (because it has been fixed there) and the servo begins to move towards position 1. The effort is futile because of the fixed position, but non the less useful to us because don't ever what it to reach position one so that we will get continues motion. When we want the motor to stop we tell it to go to position 128, since the on board electronics is thinks the motor is at position 128 it stops. The values surrounding this cause the motor to run slower because the servo thinks that it is getting close the the stopping position and we would not what to overshoot it by moving to fast. The stopped position is determined by the fixed resistors that have been used to replace the pot. If the resistors are not exactly the same value (and they never are) then the stop position will not be exactly 128.

    • Do you know if the hitec HS-300 servo motor is compatible with your board.

      I have used hitec servos in the past with the SV203 but I can not remember if it needed to be rewired. I believe some Hitec servos are wired with J-Type compatible connectors. I do not know specifically if the HS-300 will work.

    • DC Brush

  • Application Programs

  • Application Programming

  • Communications

  • SVBAS (Servo Basic)

  • Features

    • EEPROM

    • Analog to Digital Converter (ADC)

      • How do I monitor voltages larger than 5VDC with the SV203?

        My comrades and I are working on a small autonomous robot centered around the SV-203 board. Everything has been going good until now. We have plans to build a docking station to transmit data and charge our batteries. The problem arises when we try to make the robot aware of when to stop charging. The battery we are using is 6V dc. We wanted to monitor its status simply by hooking it into the input ports on the SV203 but they are only rated for 5V. Do you know if it would be safe to do so and if not do you have any other suggestions?

        Thank you,

        Jeffery Powers
        Tony Magri
        Thomas Nichol


        DO NOT EVER CONNECT GREATER THAN FIVE VOLTS TO THE INPUT PINS OF THE MICROCONTROLLER. With that said, you can lower the voltage easily enough to achieve your desired results. If you use a small voltage divider circuit you can lower the voltage into the board. If you are not familiar with ohms law it says that the voltage in a circuit is equal to the current times the resistance or E = I * R where E is the electromotive force in Volts, I is the current in Amperes and R is the resistance is Ohms. You can also arrange the formula as I = E / R or R = E / I. In the example shown E = 6V, R = 20K Ohm = 20,000 Ohm and I = E / R = 0.3 mA = 0.0003 A The Voltage across Vr1 = I * R = 0.3mA * 10K Ohm = 3V. To calculate the voltage at the pin take the value that comes in and multiply it by 5V and divide it by 255. Six volts at the battery or three volts at the A to D should give you a value of about 153.

    • IR100

    • Pin Set and Clear

    • SPI

    • Relay Control

  • Operating Systems

  • Version

  • Manual Errors