Hot Rod ROBO
The photo above shows a simple stepper driver that is the basis of my distributed control system for my 3D printer. It features low cost components and a simple design that works well. A central transceiver chip receives and sends mono audio to a TRRS jack and cable leading to a computer or cell phone. The speaker out of the driver device sends audio control signals to the Hot Rod ROBO and the microphone in line sends back audio from these stepper and heater boards. The system consists of five stepper boards as shown above, two of which contain a similar circuit designed to control the heater in response to the corresponding thermistor. One board handles the four endstop switches. This means a total of nine ATtiny85 Arduino processors and one dual opamp circuit. That and some power transistors and many small signal transistors, a handful of resistors, and some LEDs make up the entire control electronics.
