Arduino ContinuousStepper Library

An Arduino library to spin stepper motors in continuous motions.

Contrary to other stepper libraries, this one doesn't provide any function to move the shaft at a specific angle. Instead, it provides one function to spin the shaft at a specific speed. It smoothly accelerates and decelerates when the speed changes.

Features

• Supports stepper drivers with step and dir pins
• Optionally supports the enable pin
• Optionally runs with TimerOne, TimerThree or TeensyTimerTool
• Accelerates and decelerates smoothly
• Negative speed rotates backward
• Tiny footprint (about 150 lines of code)
• Uses neither delay() nor delayMicroseconds()

Suggested applications

• Tape recorders
• Conveyors
• Wheels

How to use the ContinousStepper library?

ContinuousStepper stepper;

void setup() {
  stepper.begin(stepPin, dirPin)
  stepper.spin(200); // rotate at 200 steps per seconds
}

void loop() {
  stepper.loop(); // this function must be called as frequently as possible
}

Alternatively, you can install the TimerOne to have the loop() function called in the timer interrupt handler:

ContinuousStepper_Timer1 stepper;

void setup() {
  stepper.begin(stepPin, dirPin);
  stepper.spin(200);
}

void loop() {
  // no need to call stepper.loop()
  // it's called by the timer interrupt handler
}

API

class ContinuousStepper {
public:
  // Initialize the class and attaches to the specified pins.
  void begin(pin_t stepPin, pin_t dirPin);

  // Configures the "enable" pin.
  // You can pass LOW as the second argument to invert the logic.
  // The pin is set to its active level unless powerOff() was called.
  void setEnablePin(pin_t pinNumber, bool activeLevel = HIGH);

  // Updates the status of the step and dir pins.
  // You must call this function as frequently as possible.
  void loop();

  // Sets the enable pin's level to its active level and restores the current speed.
  void powerOn();

  // Sets the enable pin's level to its inactive level.
  void powerOff();

  // Changes target speed.
  // The shaft will smoothly accelerate or decelerate to reach the
  // target speed.
  void spin(float_t speed);

  // Sets targets speed to 0.
  // The shaft will smoothly decelerate.
  // Call isSpinning() to know when the motion is complete.
  void stop();

  // Returns the current speed.
  // During accelerations and deccelerations, this value differs from the
  // target speed configured with spin().
  float_t speed() const;

  // Sets the acceleration in steps/s².
  void setAcceleration(float_t acceleration);

  // Tells wether the shaft is currently spinning.
  bool isSpinning() const;
  
  // Get counted steps since power on and running
  uint32_t getCntval() const;
};

ContinuousStepper_Timer1 is identical, except it can only have one instance and it doesn't have the loop() function.

Why use this library instead of AccelStepper

AccelStepper is an excellent library when you want to move a stepper motor shaft at a specific angle (for example, in a 3D printer), but it doesn't support applications that need continuous rotations.

AccelStepper provides a runSpeed() function for continuous motion, but it doesn't accelerate smoothly.

You could repeatedly call move(), but after a while, the 32-bit integer that stores the target position will overflow, causing the motor to reverse its rotation.

Moreover, even if you can control the speed with setMaxSpeed(), you'll see that it accelerates smoothly but decelerates abruptly.

How to migrate from AccelStepper to ContinuousStepper

AccelStepper	ContinuousStepper
disableOutputs()	powerOff()
enableOutputs()	powerOn()
isRunning()	isSpinning()
move()	spin()
moveTo()	spin()
run()	loop()
setAcceleration()	setAcceleration()
setEnablePin()	setEnablePin()
setMaxSpeed()	spin()
setMinPulseWidth()	Automatic
stop()	stop()