class Tinkerforge::BrickDC

Drives one brushed DC motor with up to 28V and 5A (peak)

Constants

CALLBACK_CURRENT_VELOCITY

This callback is triggered with the period that is set by BrickDC#set_current_velocity_period. The parameter is the current velocity used by the motor.

The CALLBACK_CURRENT_VELOCITY callback is only triggered after the set period if there is a change in the velocity.

CALLBACK_EMERGENCY_SHUTDOWN

This callback is triggered if either the current consumption is too high (above 5A) or the temperature of the driver chip is too high (above 175°C). These two possibilities are essentially the same, since the temperature will reach this threshold immediately if the motor consumes too much current. In case of a voltage below 3.3V (external or stack) this callback is triggered as well.

If this callback is triggered, the driver chip gets disabled at the same time. That means, BrickDC#enable has to be called to drive the motor again.

.. note

This callback only works in Drive/Brake mode (see BrickDC#set_drive_mode). In Drive/Coast mode it is unfortunately impossible to reliably read the overcurrent/overtemperature signal from the driver chip.

CALLBACK_UNDER_VOLTAGE

This callback is triggered when the input voltage drops below the value set by BrickDC#set_minimum_voltage. The parameter is the current voltage.

CALLBACK_VELOCITY_REACHED

This callback is triggered whenever a set velocity is reached. For example: If a velocity of 0 is present, acceleration is set to 5000 and velocity to 10000, the CALLBACK_VELOCITY_REACHED callback will be triggered after about 2 seconds, when the set velocity is actually reached.

.. note

Since we can't get any feedback from the DC motor, this only works if the acceleration (see BrickDC#set_acceleration) is set smaller or equal to the maximum acceleration of the motor. Otherwise the motor will lag behind the control value and the callback will be triggered too early.

Public Class Methods

new(uid, ipcon) click to toggle source

Creates an object with the unique device ID uid and adds it to the IP Connection ipcon.

Calls superclass method
# File lib/tinkerforge/brick_dc.rb, line 108
def initialize(uid, ipcon)
  super uid, ipcon, DEVICE_IDENTIFIER, DEVICE_DISPLAY_NAME

  @api_version = [2, 0, 3]

  @response_expected[FUNCTION_SET_VELOCITY] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_VELOCITY] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_CURRENT_VELOCITY] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_ACCELERATION] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_ACCELERATION] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_PWM_FREQUENCY] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_PWM_FREQUENCY] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_FULL_BRAKE] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_STACK_INPUT_VOLTAGE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_EXTERNAL_INPUT_VOLTAGE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_CURRENT_CONSUMPTION] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_ENABLE] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_DISABLE] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_IS_ENABLED] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_MINIMUM_VOLTAGE] = RESPONSE_EXPECTED_TRUE
  @response_expected[FUNCTION_GET_MINIMUM_VOLTAGE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_DRIVE_MODE] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_DRIVE_MODE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_CURRENT_VELOCITY_PERIOD] = RESPONSE_EXPECTED_TRUE
  @response_expected[FUNCTION_GET_CURRENT_VELOCITY_PERIOD] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_SPITFP_BAUDRATE_CONFIG] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_SPITFP_BAUDRATE_CONFIG] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_SEND_TIMEOUT_COUNT] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_SET_SPITFP_BAUDRATE] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_GET_SPITFP_BAUDRATE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_SPITFP_ERROR_COUNT] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_ENABLE_STATUS_LED] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_DISABLE_STATUS_LED] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_IS_STATUS_LED_ENABLED] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_PROTOCOL1_BRICKLET_NAME] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_CHIP_TEMPERATURE] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_RESET] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_WRITE_BRICKLET_PLUGIN] = RESPONSE_EXPECTED_FALSE
  @response_expected[FUNCTION_READ_BRICKLET_PLUGIN] = RESPONSE_EXPECTED_ALWAYS_TRUE
  @response_expected[FUNCTION_GET_IDENTITY] = RESPONSE_EXPECTED_ALWAYS_TRUE

  @callback_formats[CALLBACK_UNDER_VOLTAGE] = [10, 'S']
  @callback_formats[CALLBACK_EMERGENCY_SHUTDOWN] = [8, '']
  @callback_formats[CALLBACK_VELOCITY_REACHED] = [10, 's']
  @callback_formats[CALLBACK_CURRENT_VELOCITY] = [10, 's']

  @ipcon.add_device self
end

Public Instance Methods

disable() click to toggle source

Disables the driver chip. The configurations are kept (velocity, acceleration, etc) but the motor is not driven until it is enabled again.

.. warning

Disabling the driver chip while the motor is still turning can damage the driver chip. The motor should be stopped calling BrickDC#set_velocity with 0 before disabling the motor power. The BrickDC#set_velocity function will not wait until the motor is actually stopped. You have to explicitly wait for the appropriate time after calling the BrickDC#set_velocity function before calling the BrickDC#disable function.

# File lib/tinkerforge/brick_dc.rb, line 298
def disable
  check_validity

  send_request FUNCTION_DISABLE, [], '', 8, ''
end
disable_status_led() click to toggle source

Disables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

.. versionadded

2.3.1$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 492
def disable_status_led
  check_validity

  send_request FUNCTION_DISABLE_STATUS_LED, [], '', 8, ''
end
enable() click to toggle source

Enables the driver chip. The driver parameters can be configured (velocity, acceleration, etc) before it is enabled.

# File lib/tinkerforge/brick_dc.rb, line 282
def enable
  check_validity

  send_request FUNCTION_ENABLE, [], '', 8, ''
end
enable_status_led() click to toggle source

Enables the status LED.

The status LED is the blue LED next to the USB connector. If enabled is is on and it flickers if data is transfered. If disabled it is always off.

The default state is enabled.

.. versionadded

2.3.1$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 478
def enable_status_led
  check_validity

  send_request FUNCTION_ENABLE_STATUS_LED, [], '', 8, ''
end
full_brake() click to toggle source

Executes an active full brake.

.. warning

This function is for emergency purposes, where an immediate brake is necessary. Depending on the current velocity and the strength of the motor, a full brake can be quite violent.

Call BrickDC#set_velocity with 0 if you just want to stop the motor.

# File lib/tinkerforge/brick_dc.rb, line 240
def full_brake
  check_validity

  send_request FUNCTION_FULL_BRAKE, [], '', 8, ''
end
get_acceleration() click to toggle source

Returns the acceleration as set by BrickDC#set_acceleration.

# File lib/tinkerforge/brick_dc.rb, line 205
def get_acceleration
  check_validity

  send_request FUNCTION_GET_ACCELERATION, [], '', 10, 'S'
end
get_chip_temperature() click to toggle source

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has an accuracy of ±15%. Practically it is only useful as an indicator for temperature changes.

# File lib/tinkerforge/brick_dc.rb, line 524
def get_chip_temperature
  check_validity

  send_request FUNCTION_GET_CHIP_TEMPERATURE, [], '', 10, 's'
end
get_current_consumption() click to toggle source

Returns the current consumption of the motor.

# File lib/tinkerforge/brick_dc.rb, line 274
def get_current_consumption
  check_validity

  send_request FUNCTION_GET_CURRENT_CONSUMPTION, [], '', 10, 'S'
end
get_current_velocity() click to toggle source

Returns the current velocity of the motor. This value is different from BrickDC#get_velocity whenever the motor is currently accelerating to a goal set by BrickDC#set_velocity.

# File lib/tinkerforge/brick_dc.rb, line 182
def get_current_velocity
  check_validity

  send_request FUNCTION_GET_CURRENT_VELOCITY, [], '', 10, 's'
end
get_current_velocity_period() click to toggle source

Returns the period as set by BrickDC#set_current_velocity_period.

# File lib/tinkerforge/brick_dc.rb, line 366
def get_current_velocity_period
  check_validity

  send_request FUNCTION_GET_CURRENT_VELOCITY_PERIOD, [], '', 10, 'S'
end
get_drive_mode() click to toggle source

Returns the drive mode, as set by BrickDC#set_drive_mode.

# File lib/tinkerforge/brick_dc.rb, line 351
def get_drive_mode
  check_validity

  send_request FUNCTION_GET_DRIVE_MODE, [], '', 9, 'C'
end
get_external_input_voltage() click to toggle source

Returns the external input voltage. The external input voltage is given via the black power input connector on the DC Brick.

If there is an external input voltage and a stack input voltage, the motor will be driven by the external input voltage. If there is only a stack voltage present, the motor will be driven by this voltage.

.. warning

This means, if you have a high stack voltage and a low external voltage, the motor will be driven with the low external voltage. If you then remove the external connection, it will immediately be driven by the high stack voltage.

# File lib/tinkerforge/brick_dc.rb, line 267
def get_external_input_voltage
  check_validity

  send_request FUNCTION_GET_EXTERNAL_INPUT_VOLTAGE, [], '', 10, 'S'
end
get_identity() click to toggle source

Returns the UID, the UID where the Brick is connected to, the position, the hardware and firmware version as well as the device identifier.

The position is the position in the stack from '0' (bottom) to '8' (top).

The device identifier numbers can be found :ref:`here <device_identifier>`. |device_identifier_constant|

# File lib/tinkerforge/brick_dc.rb, line 572
def get_identity
  send_request FUNCTION_GET_IDENTITY, [], '', 33, 'Z8 Z8 k C3 C3 S'
end
get_minimum_voltage() click to toggle source

Returns the minimum voltage as set by BrickDC#set_minimum_voltage

# File lib/tinkerforge/brick_dc.rb, line 323
def get_minimum_voltage
  check_validity

  send_request FUNCTION_GET_MINIMUM_VOLTAGE, [], '', 10, 'S'
end
get_protocol1_bricklet_name(port) click to toggle source

Returns the firmware and protocol version and the name of the Bricklet for a given port.

This functions sole purpose is to allow automatic flashing of v1.x.y Bricklet plugins.

# File lib/tinkerforge/brick_dc.rb, line 512
def get_protocol1_bricklet_name(port)
  check_validity

  send_request FUNCTION_GET_PROTOCOL1_BRICKLET_NAME, [port], 'k', 52, 'C C3 Z40'
end
get_pwm_frequency() click to toggle source

Returns the PWM frequency as set by BrickDC#set_pwm_frequency.

# File lib/tinkerforge/brick_dc.rb, line 226
def get_pwm_frequency
  check_validity

  send_request FUNCTION_GET_PWM_FREQUENCY, [], '', 10, 'S'
end
get_send_timeout_count(communication_method) click to toggle source

Returns the timeout count for the different communication methods.

The methods 0-2 are available for all Bricks, 3-7 only for Master Bricks.

This function is mostly used for debugging during development, in normal operation the counters should nearly always stay at 0.

.. versionadded

2.3.3$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 415
def get_send_timeout_count(communication_method)
  check_validity

  send_request FUNCTION_GET_SEND_TIMEOUT_COUNT, [communication_method], 'C', 12, 'L'
end
get_spitfp_baudrate(bricklet_port) click to toggle source

Returns the baudrate for a given Bricklet port, see BrickDC#set_spitfp_baudrate.

.. versionadded

2.3.3$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 445
def get_spitfp_baudrate(bricklet_port)
  check_validity

  send_request FUNCTION_GET_SPITFP_BAUDRATE, [bricklet_port], 'k', 12, 'L'
end
get_spitfp_baudrate_config() click to toggle source

Returns the baudrate config, see BrickDC#set_spitfp_baudrate_config.

.. versionadded

2.3.5$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 401
def get_spitfp_baudrate_config
  check_validity

  send_request FUNCTION_GET_SPITFP_BAUDRATE_CONFIG, [], '', 13, '? L'
end
get_spitfp_error_count(bricklet_port) click to toggle source

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,

  • message checksum errors,

  • framing errors and

  • overflow errors.

The errors counts are for errors that occur on the Brick side. All Bricklets have a similar function that returns the errors on the Bricklet side.

.. versionadded

2.3.3$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 464
def get_spitfp_error_count(bricklet_port)
  check_validity

  send_request FUNCTION_GET_SPITFP_ERROR_COUNT, [bricklet_port], 'k', 24, 'L L L L'
end
get_stack_input_voltage() click to toggle source

Returns the stack input voltage. The stack input voltage is the voltage that is supplied via the stack, i.e. it is given by a Step-Down or Step-Up Power Supply.

# File lib/tinkerforge/brick_dc.rb, line 249
def get_stack_input_voltage
  check_validity

  send_request FUNCTION_GET_STACK_INPUT_VOLTAGE, [], '', 10, 'S'
end
get_velocity() click to toggle source

Returns the velocity as set by BrickDC#set_velocity.

# File lib/tinkerforge/brick_dc.rb, line 173
def get_velocity
  check_validity

  send_request FUNCTION_GET_VELOCITY, [], '', 10, 's'
end
is_enabled() click to toggle source

Returns true if the driver chip is enabled, false otherwise.

# File lib/tinkerforge/brick_dc.rb, line 305
def is_enabled
  check_validity

  send_request FUNCTION_IS_ENABLED, [], '', 9, '?'
end
is_status_led_enabled() click to toggle source

Returns true if the status LED is enabled, false otherwise.

.. versionadded

2.3.1$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 501
def is_status_led_enabled
  check_validity

  send_request FUNCTION_IS_STATUS_LED_ENABLED, [], '', 9, '?'
end
read_bricklet_plugin(port, offset) click to toggle source

Reads 32 bytes of firmware from the bricklet attached at the given port. The bytes are read starting at the position offset * 32.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

# File lib/tinkerforge/brick_dc.rb, line 558
def read_bricklet_plugin(port, offset)
  check_validity

  send_request FUNCTION_READ_BRICKLET_PLUGIN, [port, offset], 'k C', 40, 'C32'
end
register_callback(id, &block) click to toggle source

Registers a callback with ID id to the block block.

# File lib/tinkerforge/brick_dc.rb, line 577
def register_callback(id, &block)
  callback = block
  @registered_callbacks[id] = callback
end
reset() click to toggle source

Calling this function will reset the Brick. Calling this function on a Brick inside of a stack will reset the whole stack.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

# File lib/tinkerforge/brick_dc.rb, line 536
def reset
  check_validity

  send_request FUNCTION_RESET, [], '', 8, ''
end
set_acceleration(acceleration) click to toggle source

Sets the acceleration of the motor. It is given in velocity/s. An acceleration of 10000 means, that every second the velocity is increased by 10000 (or about 30% duty cycle).

For example: If the current velocity is 0 and you want to accelerate to a velocity of 16000 (about 50% duty cycle) in 10 seconds, you should set an acceleration of 1600.

If acceleration is set to 0, there is no speed ramping, i.e. a new velocity is immediately given to the motor.

# File lib/tinkerforge/brick_dc.rb, line 198
def set_acceleration(acceleration)
  check_validity

  send_request FUNCTION_SET_ACCELERATION, [acceleration], 'S', 8, ''
end
set_current_velocity_period(period) click to toggle source

Sets a period with which the CALLBACK_CURRENT_VELOCITY callback is triggered. A period of 0 turns the callback off.

# File lib/tinkerforge/brick_dc.rb, line 359
def set_current_velocity_period(period)
  check_validity

  send_request FUNCTION_SET_CURRENT_VELOCITY_PERIOD, [period], 'S', 8, ''
end
set_drive_mode(mode) click to toggle source

Sets the drive mode. Possible modes are:

  • 0 = Drive/Brake

  • 1 = Drive/Coast

These modes are different kinds of motor controls.

In Drive/Brake mode, the motor is always either driving or braking. There is no freewheeling. Advantages are: A more linear correlation between PWM and velocity, more exact accelerations and the possibility to drive with slower velocities.

In Drive/Coast mode, the motor is always either driving or freewheeling. Advantages are: Less current consumption and less demands on the motor and driver chip.

# File lib/tinkerforge/brick_dc.rb, line 344
def set_drive_mode(mode)
  check_validity

  send_request FUNCTION_SET_DRIVE_MODE, [mode], 'C', 8, ''
end
set_minimum_voltage(voltage) click to toggle source

Sets the minimum voltage, below which the CALLBACK_UNDER_VOLTAGE callback is triggered. The minimum possible value that works with the DC Brick is 6V. You can use this function to detect the discharge of a battery that is used to drive the motor. If you have a fixed power supply, you likely do not need this functionality.

# File lib/tinkerforge/brick_dc.rb, line 316
def set_minimum_voltage(voltage)
  check_validity

  send_request FUNCTION_SET_MINIMUM_VOLTAGE, [voltage], 'S', 8, ''
end
set_pwm_frequency(frequency) click to toggle source

Sets the frequency of the PWM with which the motor is driven. Often a high frequency is less noisy and the motor runs smoother. However, with a low frequency there are less switches and therefore fewer switching losses. Also with most motors lower frequencies enable higher torque.

If you have no idea what all this means, just ignore this function and use the default frequency, it will very likely work fine.

# File lib/tinkerforge/brick_dc.rb, line 219
def set_pwm_frequency(frequency)
  check_validity

  send_request FUNCTION_SET_PWM_FREQUENCY, [frequency], 'S', 8, ''
end
set_spitfp_baudrate(bricklet_port, baudrate) click to toggle source

Sets the baudrate for a specific Bricklet port.

If you want to increase the throughput of Bricklets you can increase the baudrate. If you get a high error count because of high interference (see BrickDC#get_spitfp_error_count) you can decrease the baudrate.

If the dynamic baudrate feature is enabled, the baudrate set by this function corresponds to the maximum baudrate (see BrickDC#set_spitfp_baudrate_config).

Regulatory testing is done with the default baudrate. If CE compatibility or similar is necessary in your applications we recommend to not change the baudrate.

.. versionadded

2.3.3$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 436
def set_spitfp_baudrate(bricklet_port, baudrate)
  check_validity

  send_request FUNCTION_SET_SPITFP_BAUDRATE, [bricklet_port, baudrate], 'k L', 8, ''
end
set_spitfp_baudrate_config(enable_dynamic_baudrate, minimum_dynamic_baudrate) click to toggle source

The SPITF protocol can be used with a dynamic baudrate. If the dynamic baudrate is enabled, the Brick will try to adapt the baudrate for the communication between Bricks and Bricklets according to the amount of data that is transferred.

The baudrate will be increased exponentially if lots of data is sent/received and decreased linearly if little data is sent/received.

This lowers the baudrate in applications where little data is transferred (e.g. a weather station) and increases the robustness. If there is lots of data to transfer (e.g. Thermal Imaging Bricklet) it automatically increases the baudrate as needed.

In cases where some data has to transferred as fast as possible every few seconds (e.g. RS485 Bricklet with a high baudrate but small payload) you may want to turn the dynamic baudrate off to get the highest possible performance.

The maximum value of the baudrate can be set per port with the function BrickDC#set_spitfp_baudrate. If the dynamic baudrate is disabled, the baudrate as set by BrickDC#set_spitfp_baudrate will be used statically.

.. versionadded

2.3.5$nbsp;(Firmware)

# File lib/tinkerforge/brick_dc.rb, line 392
def set_spitfp_baudrate_config(enable_dynamic_baudrate, minimum_dynamic_baudrate)
  check_validity

  send_request FUNCTION_SET_SPITFP_BAUDRATE_CONFIG, [enable_dynamic_baudrate, minimum_dynamic_baudrate], '? L', 8, ''
end
set_velocity(velocity) click to toggle source

Sets the velocity of the motor. Whereas -32767 is full speed backward, 0 is stop and 32767 is full speed forward. Depending on the acceleration (see BrickDC#set_acceleration), the motor is not immediately brought to the velocity but smoothly accelerated.

The velocity describes the duty cycle of the PWM with which the motor is controlled, e.g. a velocity of 3277 sets a PWM with a 10% duty cycle. You can not only control the duty cycle of the PWM but also the frequency, see BrickDC#set_pwm_frequency.

# File lib/tinkerforge/brick_dc.rb, line 166
def set_velocity(velocity)
  check_validity

  send_request FUNCTION_SET_VELOCITY, [velocity], 's', 8, ''
end
write_bricklet_plugin(port, offset, chunk) click to toggle source

Writes 32 bytes of firmware to the bricklet attached at the given port. The bytes are written to the position offset * 32.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

# File lib/tinkerforge/brick_dc.rb, line 547
def write_bricklet_plugin(port, offset, chunk)
  check_validity

  send_request FUNCTION_WRITE_BRICKLET_PLUGIN, [port, offset, chunk], 'k C C32', 8, ''
end