As you guessed you’ll need an external control board to use the Dynamixel motors.
There are a few of them in the market:
– Arbotix: this one is Arduino compatible, a good match for you I guess
– USB2AX: direct USB control
– OpenCM9.04 board from Robotis (Dynamixel manufacturer)
Any of those board is a nice solution, check them all out to see which one best fits your application.
On our side, the Raspberry Pi shield was built so we can communicate with Dynamixel motors. But it’s definitely not the best tool if you just want to communicate with a Dxl bus. Also, note that we don’t sell separate parts, the least you can order is a minimum kit with all Niryo One custom parts.