The ARC-S (ARduino Controller – Stepper) is an Arduinobased microcontroller board with an integrated stepper drive. ARC-S combines the powerful convenience of the Arduino platform with the proven AllegroA4988 stepper motor driver. In addition, built-in push buttons on the board can be used as a simple control panel. ARC-S comes with open source sample code and is perfect for proof-of-concept, rapid prototyping, DIY projects and more. ARC-S is plug and play - a DC power supply, stepper motor and ARC-S board is the bare minimum needed to get your project running.
· 99% Compatible with Arduino Mega Rev3.
· Software controlled microstep settings.
· 2 adjustable presets for motor current (software switchable).
· Improved heat dissipation (PCB + heatsink).
· On-board push button and switches.
· Open source sample code and library.
Operating Voltage (Microcontroller)
Max DC Current per Pin
Operating Voltage (Stepper Driver)
Max Output Current (Stepper Driver)
Full, 1/2, 1/4, 1/8, 1/16
113 x 53.3 x 19mm
 Arduino® and other Arduino brands and logos are trademarks of Arduino AG.
Allegro® is a registered trademark of Allegro MicroSystems, LLC
Sample Code and Library
ARC-S comes shipped with sample code pre-programmed into the microcontroller. The default code allows the user to start or stop the motor, change its direction, and adjust its speed. Other sample code and a free for use open source library is provided on Github: https://github.com/MotorDynamicsLab/arduino-controller-stepper.
The ARC-S can be reprogrammed multiple times and can be used as a normal Arduino Mega board. The lightweight Arduino IDE can be used to program the ARC-S board (identified in the IDE as Arduino Mega 2560). The IDE, along with extensive documentation is available from the official Arduino website: https://www.arduino.cc/en/Main/Software
The microcontroller in ARC-S can be powered with either the USB cable or DC power supply (V+/- terminals). A USB only connection only provides enough power for the basic Arduino functionality. The DC power supply can supply power to both the Arduino and Stepper Driver. ARC-S accepts voltage ranges of 10 – 24V from the V+ and V- terminals. When using DC power supply, the Arduino microcontroller will derive its 5V power from the onboard 78M05 voltage regulator - capable of supplying up to 1A of current.
Stepper Current Control
The current output to the stepper motor can be adjusted using the two trimpots IADJ1 and IADJ2. Motor current is derived from the following equation:
Imotor= Vref / 8 *Rs = Vref/ 0.8
Where Rs= 0.1Ω is the value of the current sense resistor.
The via labeled VREF allows Vref to be measured easily using a multimeter. A switch (controlled by the Arduino) allows the user to switch between normal current mode (adjusted solely using IADJ1) and reduced current mode (adjusted using both IADJ1 and IADJ2).
The heat generated by the onboard stepper driver chip is directly proportional to the current settings of the driver. At high current settings, the hot temperature on the driver chip can reduce the lifespan or even cause a thermal shutdown. ARC-S dissipates heat generated from the driver chip by using the PCB bottom copper plane as a passive heatsink. In addition, a large aluminum heatsink is provided, which can be attached to provide additional heat dissipation.
The ARC-S design derives from the Arduino Mega Rev3 while adding additional features such as the integrated stepper driver and pushbutton control panel. The PCB outline of ARC-S is identical to the Arduino Mega Rev3. The USB socket, I/O pin headers, ICSP headers and reset switch are also in identical positions compared to the Arduino Mega. When not used for controlling stepper motors, the ARC-S can be used as an ordinary Arduino Mega microcontroller board.