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

I hooked up the power supply for my SVxxx[B/C] backward and now it will not operate properly (at all), what happened?

You blew the voltage regulator, this may or may not have damaged the PIC micro controller. Try to avoid this with all precautions.

In reading the SV203 User's Manual, it says that the board should be powered at 6VDC, at 300 mA. What would happen to the board if the current were increased to 3 Amps?

On Sat, 8 Jun 2002, Jacob wrote:

Well, actually, the board only requires about 20mA, the extra current is for the servo motors. A servo motor can draw 100+mA depending on it's size. Also, if you have a 6V 100,000Amp power supply that is constant voltage (as are most) then the board will only pull 20mA. The current rating of a power supply is typically a maximum current that the supply can deliver. When that limit is reached something has to give and it's usually voltage (but it could be a fuse). When the current limit is reached and voltage goes (down), that is when you start to see things like motors fluttering or board stop operating.

How good is the voltage regulation off of PWR1? My concern is that I'll be using pots for inputs. -Chikyung Won

It can get pretty messy when motors are running. (See previous question)

When would I need to use optional servo power (PWR2)? If I do use PWR2, I assume I need to close JP1 and still provide 6V to PWR1. -Chikyung Won

The intention of the PWR2 connector was if you wanted to use high voltage servos > 10 volts or so. To use the connector, you would need to cut the power trace for the servos somewhere along the connector path. JP1 is provided to jump the low voltage back into the cut trace if you wanted to re-provide low power to all servos

I am in near panic mode. I am using your servo controller boards for a design project and require the use of 2 boards (there are 13 motors involved).

I follow the diagram presented in the Product Manual (connecting the power supplies as well as the other connection because I am only outputting), but when both boards are connected to a common power supply it seems like nothing can get the boards to function correctly. As I try to output commands all of the motors seem to stall and just vibrate. If I cut the wires that tie the power supplies of the two seperate boards and use each board individually (using the exact same program), everything works fine.

Have you heard of this problem before? Any suggestions that would allow both controller boards to work at the same time?

A second question is: sometimes when I am moving two or more servo motors in the same line of code, other motors in the system that are supposed to be stationary begin to vibrate (or sometimes move). I was told that this could be due to the default gain of the board and I should lower the default setting of the gain. Is this correct, and if so how is this done (or can it be done)? I did not see such information provided in the manual.

Thank you very much in advance for your time and help.

Chris Nowakowski
Mechanical Engineering Graduate Student
Bucknell University

On Sat, 8 Jun 2002, Jacob wrote:

It sounds more like your power supply does not have enough current to drive all the motors. if you are using 13 servo motors I would be using a power supply that can output at least 2.5 Amps, maybe more depending on the size of the servos. All the problems you described are things that I have experienced from not having a large enough power supply.

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

SBC

Third Party

VSA

Application Programming

JAVA

MS Visual C++

MS Visual Basic

Communications

RS-232

Multiple Boards

USB

No SV products have support for USB.

SVBAS (Servo Basic)

Compiler

Downloading Problems

Code Examples

Starting and stopping programs

The “hidden” command that will start and stop the SV203[B/C]

RUN will start the program

^C (control-C) (ACSII 3) will stop the program

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.