8 Servos 128 / 3500 steps Midi

Description of the Servomotor board

The 8 Servomotors Interface-Z board allows you to control up to 8 servomotors simply by sending them position commands in real-time. The board then ensures that each object stays in the chosen position until the next movement.

8 servo control board.

One single board is enough to control the motors with 128 positions (in standard Midi) or 3500 steps. These positions are distributed along the chosen range: 90° or 120° (or even 180°). This board also allows you to memorize rest positions and has a safety mode.

This demonstration video, created by Clément Payen, shows a small sound application with sticks striking cups and glasses. The programming was done in Max and uses the 8 Servos board in 128-step mode.

What is a servomotor? It’s a motor controlled in position. They are used to animate sculptures, robots, puppets, models, lighting, etc.

These motors rotate or place objects of varying weights (up to several kilograms) at a precise position. The most common ones allow positioning for a quarter or half-turn. Some rotate continuously at variable speed, others are servo-winches with multiple turns. The variety of adaptable heads, fixed on the axis, allows any object to be moved.

Servomotors can be found in modeling stores, but we can also supply them. The documentation shows how to connect them regardless of the brand.

For more details on servomotors, refer to the "Servomotor" page in the Tips section.

Our servomotor control boards are compatible with all types of classic motors: mini-servos, metal gears, winches, continuous rotation, etc. The only thing to check is the order of the wires – it is usually compatible with our boards, but there may be variations.

Examples of applications

Objects fixed on servomotors can be:

- tools: sensors (rangefinders, cameras, optical systems, cameras, etc.) or control buttons (adjustment potentiometers for devices, adjustment sliders);
- or elements of sculptures or decor, contributing to the visual effect perceived by the public in the installation.

Examples of using servomotors.

By attaching sticks to the rotating head of the motors, you can create puppet animations, whose movements could be linked to music, the behavior of the audience, or even atmospheric conditions.

They are also used to block light projectors or video projectors completely or partially with perforated plates (thus enabling an absolute black effect).

They can also be used to orient objects, move lights, or small cameras.
Using modeling winches, you can tension wires to move fabrics or make objects rise and fall.

Coupling two servomotors allows you to orient an object in all three directions of space and thus create small robots.

Technical Notes

Power Supply, Rest Position, Safety Mode, Interference... Some things to know.

Sizing

You need to size the motors according to the weight they need to lift: a motor that's too weak will strain and risk breaking.

Motor Sizing

On the left, a motor that's too weak, straining; on the right, a motor that's powerful enough for this application.

Knowledge About the Board

How to connect servomotors to the board, what power supply to use, and which software is compatible with the board?

Management of 8 servomotors

• The system can run on a 9V battery for the board and a modeling battery pack for the servomotors, in case of a mobile application (e.g., walking robot).
• The memorization of rest positions allows you to control the position of the motors when the board is connected but not receiving any commands.
• The Safety mode prevents the motors from being forced in case of programming failure (provided that comfortable rest positions have been defined for the setup).
• Beware of long extensions: servomotors typically have very short connection wires, which are directly plugged into the board. If the motor needs to be placed farther from the board, simply plugging it into a 3-wire extension like for sensors is not enough. The motor may vibrate and disobey commands. The solution is to place a small noise filter between the servo and the extension. If the distance between the board and the servo exceeds 3 meters, it’s better if the extension itself is shielded.
• The built-in Midi split allows chaining multiple actuator boards.

Connections, Control, Power Supply, etc.

Compatibility and Control

To be adaptable to anything, the 8 Servomotors module can be controlled from any software capable of sending Midi Control Change messages, such as: Max / MSP, Isadora, Usine, Pure-Data, Ableton Live, VVVV, EyesWeb, Processing, etc...

The channels and message numbers are configurable, which allows you to manage 8 boards (64 servomotors) per Midi channel and 16 channels, so a total of 512 servomotors.

Connectivity and Mounting

• Midi input;
• Built-in Midi splitter output;
• 8 connectors for servomotors, 3-pin pins;
• 4-pin power supply connector for low voltage power supplies;
• 4 mounting positions at the corners.

Connecting the Servomotors

Be careful not to reverse the connections to avoid damaging the motor. Markings on the board guide you in making the correct connections.

Remarques technique

Technical Notes

• For the board: 9V to 15V DC, capable of providing 100mA
• For the servomotors: 4.5V to 6V DC, capable of providing 8A

This short video shows the available wires on this type of power supply.

Power supply not included!

Servomotor Adjustment

Standard servomotor range adjustable to 90° or 120°, in 128 steps or 3500 steps.

Safety Mode and Rest Position Memory

The board is controlled by activating switches on the board.

The position memory ensures that upon the next start of the board, the servomotors return to the chosen positions.

• Be careful not to activate the memory if you don’t want to use it.

Safety mode ensures that, in the absence of Midi commands, the servomotors return to rest positions. For example, in case of a sudden shutdown of the computer controlling the motors, this prevents forcing, overheating, and damage.

Built-in Midi Split

The Midi output (marked Out) sends out the Midi messages received, allowing you to control another actuator board directly connected to the Servomotors board. This saves a Midi output port on the computer controlling the installation.

Be careful with running status in Midi.

Documentation, Programming, and Resources

Documentation:

• 8-Servo-128-3500.pdf Documentation
• Servomotor information page

Midi Servo Board Patches Download:

• 128-step patches for Isadora, Max, Pure Data, with explanations
• 3500-step patches, with explanations
• Archive of 128-step patches for Isadora, Max, PD + docs
• Archive of 3500-step patches + docs

Kit Version Assembly

Reminder: The partial kit only contains the printed circuit board and the programmed component. The rest of the components must be sourced separately.

• Kit filter for extensions: Rallonge-Servo.pdf

Kit Assembly Help:

You can refer to the pages of help on component identification and markings: Nomenclature and description of electronic components

Older Versions

The current board is an evolution of older boards.

8 Servos 128 / 3500 steps without split

This board works exactly the same as the current one. The only difference is that it does not have the Midi split.
Documentation: 8-Servo-128-3500.pdf

8 Servos 128 / 8 Servos 3500 steps distinct

Description pages remain online for users of previous versions. The current board is fully compatible with programs designed to work with the two older boards, but you must verify whether it is set to 128 or 3500 steps.

Older board
Documentation for older boards:
• Midi-SERVO 128 steps: Midi-Servo-128.pdf
• Midi-SERVO 3500 steps: Midi-Servo-3500.pdf