Documentation

Servo Board

A photo of a servo board The Servo Board can be used to control up to 12 RC servos. Many devices are available that can be controlled as servos, such as RC motor speed controllers, so these can also be used with this board.

Board Diagram

A diagram of a servo board

Indicators

LED Meaning Initial power-up state
Power The board is powered over USB. On
5.5V On There is 5.5V power on the board. This usually indicates that the 12V connector rail is powered. Off
Aux On There is auxiliary power on the board. On
STATUS|ERROR Blue when the board has successfully booted
Solid pink if 12V power is lost
Blue

Connectors

There are 8 servo connections on the left-side of the board (numbers 0-7), and 4 auxiliary outputs on the right (numbers 8-11). See the labels on the board (also visible in the photo above) for how these numbers map to the outputs.

Servo cables are connected vertically, with 0V (the black or brown wire) at the bottom of the board.

For the servo board to operate correctly, you must connect it to the 12V power rail from the power board. A green LED will light next to the servo board 12V connector when it is correctly powered.

Auxiliary outputs

Servo outputs 8-11 are supplied from the separate auxiliary power input. If you want to use these ports the power has to be connected to either the a 5V or 12V output of the power board.

Only connect 12V to the auxiliary power input if the servos connected to port 8-11 support 12V.

Case Dimensions

The case measures 68×68×21mm. Don’t forget that the cables will stick out.

Servo Control

For an RC servo the angle of rotation is determined by the width of an electrical pulse on the control wire. This is a form of pulse-width modulation. (PWM) A typical servo expects to see a pulse every 20ms, however this can vary from servo to servo.

The Servo Board is able to precisely control the duration of the pulses sent to servos (based on the values you configure using the Python API), within the ranges in the table below.

Specification

Parameter Value
Number of servo channels 12
Nominal input voltage 11.1V ± 15%
Output voltage 5.5V
Maximum total output current 1 10A
Default pulse range 1ms — 2ms
Maximum pulse range 0.5ms — 4ms
Pulse precision 5µs

Designs

You can access the schematics and source code of the firmware on the servo board in the following places. You do not need this information to use the board but it may be of interest to some people.

  1. If the auxiliary input is connected, outputs 8-11 have an independent maximum current.