Easy Driver

Arduino Connecting Easy Driver Stepper Motor Controller

by Lewis Loflin

EasyDriver by Brian Schmalz is licensed under a Creative Commons Attribution 3.0 United States License. Based on a work at www.schmalzhaus.com/EasyDriver. Built on the Allegro A3967 it was a replacement for the UCN5804B stepper motor driver chip. I'm using it as a replacement for the equally hard to find and costly MC3479 stepper motor controller.

This really consists of a circuit board with a surface mount integrated circuit. The board costs between $10 to $15. While designed to operate low-power bipolar stepper motors with a current limit of about 700 mA, we can do a lot more.

Easy Driver combined with a L298N driver

The four outputs for two motor windings (A and B) can drive power MOSFETs or bipolar transistors to operate in the unipolar mode. The power can be boosted by using the four outputs to drive a L298N bipolar type driver board.

Note that with the logic levels on MS1 and MS2 we can select from full step to one-eighth step. In the case of my test motor it was 1.8 degrees per step or 200 steps for 360 degrees of rotation. That same motor in half-step mode requires 400 steps; in quarter-step mode 800 steps; and in eighth-step mode requires 1600 step.

Each "step" requires a positive going pulse on the step pin. Direction is determined by a LOW or HIGH on the direction pin. Note that to reverse direction of rotation swap the wire pairs between A and B.

The advantage is the advanced hardware control simplifies programming and interfacing.

Sparkfun (www.sparkfun.com) a seller of Easy Driver says,

The EasyDriver is a simple to use stepper motor driver, compatible with anything that can output a digital 0 to 5V pulse (or 0 to 3.3V pulse if you solder SJ2 closed on the EasyDriver). EasyDriver requires a 7V to 30V supply to power the motor and can power any voltage of stepper motor. The EasyDriver has an on board voltage regulator for the digital interface that can be set to 5V or 3.3V.

Connect a 4-wire stepper motor and a micro-controller and you've got precision motor control! EasyDriver drives bipolar motors, and motors wired as bipolar. I.e. 4,6, or 8 wire stepper motors.

A3967 microstepping driver.

MS1 and MS2 pins broken out to change microstepping resolution to full, half, quarter and eighth steps (defaults to eighth).

Compatible with 4, 6, and 8 wire stepper motors of any voltage.

Adjustable current control from 150mA/phase to 750mA/phase.

Power supply range from 7V to 30V. The higher the voltage, the higher the torque at high speeds.

Enable Input (ENABLE). This active-low input enables all of the outputs. When logic high the outputs are disabled. Inputs to the translator (STEP, DIRECTION, Ms1, Ms2) are all active independent of the ENABLE input state.

Sleep Mode (SLEEP). An active-low control input used to minimize power consumption when not in use. This disables much of the internal circuitry including the outputs. A logic high allows normal operation and startup of the device in the home position.

Easy Driver combined bipolar transistors

VM is the motor voltage. R1 - R4 are 1000-2200 ohms. While the module has a built in 5-volt regular don't use it to power other circuits because it gets hot.

If one decides to operate a unipolar (six wire) stepper motor in the bipolar (four wire) mode DOUBLE the winding voltage.

Sample Code

Download sample Arduino code stepper_easy_arduino.txt.

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