StepMotor Class Reference

API for the Stepper Motor. More...

Detailed Description

• ID: stepmotor
• Name: Stepper Motor
• Other Names: EasyDriver Stepper Motor Driver
• Category: motor
• Manufacturer: sparkfun generic
• Link: http://www.schmalzhaus.com/EasyDriver/index.html
• Connection: gpio

This module defines the Stepper Motor interface. It is compatible with stepper motor drivers that use 2 pins to control the motor, like an Easy Driver from Brian Schmalz or the STR driver series from Applied Motion. It can also control an enable pin if one is available and connected.

The implementation is synchronous and thus blocking while the stepper motor is in motion. However it is possible to send the commands via threading and the performance of the library will be very good given a low CPU load. On a busy system though you will notice some jitter especially at higher speeds. It is possible to reduce this effect to some extent by using smoothing and/or microstepping on stepper drivers that support such features.

EasyDriver Sensor image provided by SparkFun* under CC BY 2.0.

    upm::StepMotor sensor(2, 3);

    while (doWork) {
        cout << "1 Revolution forward and back at 60 rpm" << endl;
        sensor.setSpeed(60);
        sensor.stepForward(200);
        upm_delay_us(1000000);
        sensor.stepBackward(200);
        upm_delay_us(1000000);

        cout << "1 Revolution forward and back at 150 rpm" << endl;
        sensor.setSpeed(150);
        sensor.stepForward(200);
        upm_delay_us(1000000);
        sensor.stepBackward(200);
        upm_delay_us(1000000);

        cout << "1 Revolution forward and back at 300 rpm" << endl;
        sensor.setSpeed(300);
        sensor.stepForward(200);
        upm_delay_us(1000000);
        sensor.stepBackward(200);
        upm_delay_us(1000000);
    }

Public Member Functions
	StepMotor (int dirPin, int stePin, int steps=200, int enPin=-1)
	~StepMotor ()
void	enable (bool flag)
void	setSpeed (int speed)
mraa::Result	step (int ticks)
mraa::Result	stepForward (int ticks)
mraa::Result	stepBackward (int ticks)
void	setPosition (int pos)
int	getPosition ()
int	getStep ()

Constructor & Destructor Documentation

StepMotor	(	int	dirPin,
		int	stePin,
		int	steps = 200,
		int	enPin = -1
	)

Instantiates a StepMotor object.

Parameters

dirPin	Direction GPIO pin
stePin	Stepper pulse GPIO pin
steps	Number of steps per revolution (Default 200)
enPin	Enable pin if connected (Optional)

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~StepMotor

(

)

StepMotor object destructor.

Member Function Documentation

void enable

(

bool

flag

)

Can be used to enable/disable the stepper driver if an enable pin is available and connected. Check your data sheet as some drivers might have the enable logic inverted.

Parameters

flag	true to enable or false to disable

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void setSpeed

(

int

speed

)

Sets the rotation speed in rpm. Default 60 rpm.

Parameters

speed

Rotation speed in rpm

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mraa::Result step

(

int

ticks

)

Rotates the motor by the specified number of steps. Positive values rotate clockwise and negative values rotate counter-clockwise.

Parameters

ticks

Number of steps the motor moves

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mraa::Result stepForward

(

int

ticks

)

Rotates the motor forward (clockwise).

Parameters

ticks

Number of steps the motor moves

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mraa::Result stepBackward

(

int

ticks

)

Rotates the motor backward (counter-clockwise).

Parameters

ticks

Number of steps the motor moves

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void setPosition

(

int

pos

)

Sets the current position. Useful if the motor is not at 0 when the driver is initialized.

Parameters

pos	Current position

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int getPosition

(

)

Gets the current position. This is cumulative and the result of all the step commands sent to the motor.

Returns

Stepper's position.

int getStep

(

)

Gets the current step. This is relative to one revolution.

Returns

Current step, ranges from 0 to number of steps per revolution.

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The documentation for this class was generated from the following files:

• src/stepmotor/stepmotor.hpp
• src/stepmotor/stepmotor.cxx