Devantech SD21 - 21 Channel Servo Driver

The SD21 is a 21 channel servo controller module that works with most microcontrollers including Arduino, PICAXE, Orangutan. It will drive up to 21 RC servo's and maintain a 20mS refresh rate, regardless of the number of servo's used or their positions (pulse widths). It will control both position and speed of the servo's.

Not currently available

Our Code: MCU-60029


The SD21 is controlled by sending commands to the on-board PIC18F2220 over the I2C bus. There are 3 I2C connectors on the board, any one of which can be used to connect to your controller. Alternatively, many controllers such as the Picaxe 18X, BS2p, Atom, BX-24 etc. can be fitted directly to the module, making this a great animatronics controller. By using an I2C interface the controller frees up the precious serial pins on controllers like the Arduino for other uses. 


The module can be powered using two seperate supplies for logic circuits and servos or using a shared supply via an on board low drop 5V regulator.

Adding on-board controllers

Two sockets on the SD21 allow you to add microcontrollers directly onto the board to provide the brains making it great for animatronics.

A 24 pin socket on the SD21 will accept a BS2p or compatible controller such as the ATOM or BX-24. An 18 pin socket on the SD21 will accept the PICAXE-18X.

SD21 with a PICAXE 18X chip fitted SD21 with a Basic Stamp Fitted