This servo controller can be used to manually control two servos, using standard RC servo PWM control. It was created by members of First Tech Challenge team 4137 Islandbots.

Features

• Independent control of two servos
• Built-in battery holder (4 AA batteries)
• Screen to show servo positions (pulse width and position in range 0.0 - 1.0)
• Three selectable ranges (800 - 2200, 600-2400, 500 - 2500)
• Ability to save and recall servo positions at a press of a button
• Size (LxWxH): 93mm x 69mm x 50mm, including the knobs

Experimental feature: smart servo programming

The controller also provides an option to set the mode of "dual mode servos", such as REV Robotics smart servo or goBilda dual mode servos (both of which, as far as I know, use Feetech servo protocol). This feature should be considered experimental. It works in our testing, but it has not yet been extensively tested, so use caution. If you are heading to a competition, make sure to have a REV or goBilda programmer as a backup.

Usage

Most usage is self-explanatory. The screen shows position for each servo, both as pulse width in microseconds and as a number in range 0.0 - 1.0, which makes it very convenient for later entering the servo values in your code.

You can save and recall servo positions using buttons. To save current servo position, press and hold a button for 2 seconds. To move the servo to one of the saved positions, just press a button. Button A only controls position of servo 1, buttons B, C control positions of both servos, and button D only controls position of servo 2. Note that only one button can be active at any moment: you can not activate buttons A and D at the same time.

To return to normal operation, press and release the same button again.

To program a dual mode servo, connect it to servo port 1 before powering the controller and follow menu prompts.

Batteries

The controller is powered by 4 AA batteries (not included). To replace the batteries, remove the bottom plate, using a screwdriver. It is recommended that you turn the controller off before replacing the batteries. You can use alcaline or NiMH rechargeable batteries.

License and source code

All source files (KiCad files for the board, BOM, source code for firmware) are available from the project github repository under an open source license.

Serial servo use

The controller contains hardware allowing it to communicate with serial servos such as Dynamixel on servo port 1 only; however, current firmware does not support these servos. Advanced users can write their own firmware, using Arduino and their favorite Dynamixel library; please see DYNAMIXEL file in github repository for more info.

Please note:

• Since most serial servos use higher voltage (12v or 24 v are common), you will need to connect a separate power source for them, only using GND and SIGNAL pins of servo controller port 1.

• No support is provided for using this controller with serial servos - you are doing it at your own risk.