The Raspberry Pi is capable of communicating with the Dynamixel AX-12A smart servos via several methods. At this point, we recommend via serial port through an OpenCM 9.04 Arduino-compatible board.

Other options include:

• Via USB using the USB2Dynamixel adapter. The most straightforward option but also the most expensive per-unit (USB2Dynamixel adapters are around $60) and the USB2Dynamixel adapter isn't exactly small. We have also found some reliability issues with doing this.
• Via serial port through a 74LS241 driver chip. The cheapest option. WARNING: THIS OPTION HAS STABILITY PROBLEMS. AVOID IT FOR NOW.