API for the I2C Motor Driver. More...

Detailed Description

ID: md
Name: I2C Motor Driver
Other Names: Grove Motor Driver
Category: motor
Manufacturer: seeed
Connection: i2c
Link: http://wiki.seeed.cc/Grove-I2C_Motor_Driver_V1.3/
Kit: robok

This class implements support for the I2C Motor Driver. This device can support a single 4-wire stepper motor, or two 2-wire DC motors. The device contains an Atmel* ATmega8L microcontroller that manages an L298N H-bridge driver chip.

This device supports an I2C bus speed of 100Khz only.

The module does not provide any telemetry or status - it only accepts I2C commands for its various operations.

This module was tested with version 1.3 of the I2C Motor Driver.

For stepper operation, this driver can run in one of two modes - Mode 1, where this driver handles the stepping operation, and Mode 2, where this driver simply sends commands to the Motor Driver, and it handles the stepping operation. Mode2 requires updated (and working) firmware to be loaded onto the device.

The default stepper operation mode is Mode1, which is generally more flexible and is supported on all firmware revisions.

An example showing the use of a DC motor

    // Instantiate an I2C Motor Driver on I2C bus 0
    upm::MD motors(MD_I2C_BUS, MD_DEFAULT_I2C_ADDR);
    // set direction to CW and set speed to 50%
    cout << "Spin M1 and M2 at half speed for 3 seconds" << endl;
    motors.setMotorDirections(MD_DIR_CW, MD_DIR_CW);
    motors.setMotorSpeeds(127, 127);
    upm_delay(3);
    // counter clockwise
    cout << "Reversing M1 and M2 for 3 seconds" << endl;
    motors.setMotorDirections(MD_DIR_CCW, MD_DIR_CCW);
    upm_delay(3);

An example showing the use of a 4-wire stepper

    // Instantiate an I2C Motor Driver on I2C bus 0
    upm::MD motors(MD_I2C_BUS, MD_DEFAULT_I2C_ADDR);
    // This example demonstrates using the MD to drive a stepper motor
    // configure it, for this example, we'll assume 200 steps per rev
    motors.configStepper(200);
    // set for half a rotation
    motors.setStepperSteps(100);
    // let it go - clockwise rotation, 10 RPM speed
    motors.enableStepper(MD_STEP_DIR_CW, 10);
    upm_delay(3);
    // Now do it backwards...
    motors.setStepperSteps(100);
    motors.enableStepper(MD_STEP_DIR_CCW, 10);
    // now disable
    motors.disableStepper();

Public Member Functions
	MD (int bus=MD_I2C_BUS, uint8_t address=MD_DEFAULT_I2C_ADDR)

	~MD ()

bool	writePacket (MD_REG_T reg, uint8_t data1, uint8_t data2)

bool	setMotorSpeeds (uint8_t speedA, uint8_t speedB)

bool	setPWMFrequencyPrescale (uint8_t freq=0x03)

bool	setMotorDirections (MD_DC_DIRECTION_T dirA, MD_DC_DIRECTION_T dirB)

bool	enableStepper (MD_STEP_DIRECTION_T dir, uint8_t speed)

bool	disableStepper ()

bool	setStepperSteps (unsigned int steps)

void	configStepper (unsigned int stepsPerRev, MD_STEP_MODE_T mode=MD_STEP_MODE1)

Protected Attributes
md_context	m_md

Constructor & Destructor Documentation

MD	(	int	bus = `MD_I2C_BUS`,
		uint8_t	address = `MD_DEFAULT_I2C_ADDR`
	)

MD constructor

Parameters

bus	I2C bus to use
address	I2C address to use

~MD ( )

MD destructor

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Member Function Documentation

bool writePacket	(	MD_REG_T	reg,
		uint8_t	data1,
		uint8_t	data2
	)

Composes and writes a 3-byte packet to the controller

Parameters

reg	Register location
data1	First byte of data
data2	Second byte of data

Returns: True if successful

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bool setMotorSpeeds	(	uint8_t	speedA,
		uint8_t	speedB
	)

To control DC motors, sets the speed of motors A & B. Valid values are 0-255.

Parameters

speedA	Speed of motor A
speedB	Speed of motor B

Returns: True if successful

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bool setPWMFrequencyPrescale ( uint8_t freq = 0x03 )

To control DC motors, sets the PWM frequency prescale factor. Note: this register is not ducumented other than to say the default value is 0x03. Presumably, this is the timer prescale factor used on the ATMega MCU timer driving the PWM.

Parameters

freq	PWM prescale frequency; default is 0x03

Returns: True if successful

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bool setMotorDirections	(	MD_DC_DIRECTION_T	dirA,
		MD_DC_DIRECTION_T	dirB
	)

To control DC motors, sets the directions of motors A & B

Parameters

dirA	Direction for motor A, DIR_CW or DIR_CCW
dirB	Direction for motor B, DIR_CW or DIR_CCW

Returns: True if successful

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bool enableStepper	(	MD_STEP_DIRECTION_T	dir,
		uint8_t	speed
	)

To control a stepper motor, sets its direction and speed, and then starts operation. For Mode2, this method will return immediately. For Mode1 (the default) this method returns when the number of steps specified by setStepperSteps() has completed.

Parameters

dir	Direction, STEP_DIR_CW or STEP_DIR_CCW
speed	Motor speed. Valid range is 1-255. For Mode 1 (default), this specifies the speed in RPM's. For Mode 2, speed is multiplied by 4ms by the board, so higher numbers will mean a slower speed.