JavaScript - DC Brick

This is the description of the JavaScript API bindings for the DC Brick. General information and technical specifications for the DC Brick are summarized in its hardware description.

An installation guide for the JavaScript API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Configuration (Node.js)

Download (ExampleConfiguration.js)

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var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XXYYZZ'; // Change XXYYZZ to the UID of your DC Brick

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var dc = new Tinkerforge.BrickDC(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        dc.setDriveMode(Tinkerforge.BrickDC.DRIVE_MODE_DRIVE_COAST);
        dc.setPWMFrequency(10000); // Use PWM frequency of 10kHz
        dc.setAcceleration(5000); // Slow acceleration
        dc.setVelocity(32767); // Full speed forward
        dc.enable(); // Enable motor power
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        dc.disable(); // Disable motor power
        ipcon.disconnect();
        process.exit(0);
    }
);

Callback (Node.js)

Download (ExampleCallback.js)

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var Tinkerforge = require('tinkerforge');

var HOST = 'localhost';
var PORT = 4223;
var UID = 'XXYYZZ'; // Change XXYYZZ to the UID of your DC Brick

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var dc = new Tinkerforge.BrickDC(UID, ipcon); // Create device object

ipcon.connect(HOST, PORT,
    function (error) {
        console.log('Error: ' + error);
    }
); // Connect to brickd
// Don't use device before ipcon is connected

ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
    function (connectReason) {
        // The acceleration has to be smaller or equal to the maximum
        // acceleration of the DC motor, otherwise the velocity reached
        // callback will be called too early
        dc.setAcceleration(5000); // Slow acceleration
        dc.setVelocity(32767); // Full speed forward

        // Enable motor power
        dc.enable();
    }
);

// Register velocity reached callback
dc.on(Tinkerforge.BrickDC.CALLBACK_VELOCITY_REACHED,
    // Use velocity reached callback to swing back and forth
    // between full speed forward and full speed backward
    function (velocity) {
        if(velocity == 32767) {
            console.log('Velocity: Full speed forward, now turning backward');
            dc.setVelocity(-32767);
        }
        else if(velocity === -32767) {
            console.log('Velocity: Full speed backward, now turning forward');
            dc.setVelocity(32767);
        }
        else {
            console.log('Error'); // Can only happen if another program sets velocity
        }
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        dc.disable(); // Disable motor power
        ipcon.disconnect();
        process.exit(0);
    }
);

Configuration (HTML)

Download (ExampleConfiguration.html), Test (ExampleConfiguration.html)

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<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>DC Brick Configuration Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var dc = new Tinkerforge.BrickDC(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        dc.setDriveMode(Tinkerforge.BrickDC.DRIVE_MODE_DRIVE_COAST);
                        dc.setPWMFrequency(10000); // Use PWM frequency of 10kHz
                        dc.setAcceleration(5000); // Slow acceleration
                        dc.setVelocity(32767); // Full speed forward
                        dc.enable(); // Enable motor power
                    }
                );
            }
        </script>
    </body>
</html>

Callback (HTML)

Download (ExampleCallback.html), Test (ExampleCallback.html)

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<!DOCTYPE html>
<html>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <head>
        <title>Tinkerforge | JavaScript Example</title>
    </head>
    <body>
        <div style="text-align:center;">
            <h1>DC Brick Callback Example</h1>
            <p>
                <input value="localhost" id="host" type="text" size="20">:
                <input value="4280" id="port" type="text" size="5">,
                <input value="uid" id="uid" type="text" size="5">
                <input value="Start Example" id="start" type="button" onclick="startExample();">
            </p>
            <p>
                <textarea readonly id="text" cols="80" rows="24" style="resize:none;"
                          >Press "Start Example" to begin ...</textarea>
            </p>
        </div>
        <script src="./Tinkerforge.js" type='text/javascript'></script>
        <script type='text/javascript'>
            var ipcon;
            var textArea = document.getElementById("text");
            function startExample() {
                textArea.value = "";
                var HOST = document.getElementById("host").value;
                var PORT = parseInt(document.getElementById("port").value);
                var UID = document.getElementById("uid").value;
                if(ipcon !== undefined) {
                    ipcon.disconnect();
                }
                ipcon = new Tinkerforge.IPConnection(); // Create IP connection
                var dc = new Tinkerforge.BrickDC(UID, ipcon); // Create device object
                ipcon.connect(HOST, PORT,
                    function(error) {
                        textArea.value += 'Error: ' + error + '\n';
                    }
                ); // Connect to brickd
                // Don't use device before ipcon is connected

                ipcon.on(Tinkerforge.IPConnection.CALLBACK_CONNECTED,
                    function (connectReason) {
                        // The acceleration has to be smaller or equal to the maximum
                        // acceleration of the DC motor, otherwise the velocity reached
                        // callback will be called too early
                        dc.setAcceleration(5000); // Slow acceleration
                        dc.setVelocity(32767); // Full speed forward

                        // Enable motor power
                        dc.enable();
                    }
                );

                // Register velocity reached callback
                dc.on(Tinkerforge.BrickDC.CALLBACK_VELOCITY_REACHED,
                    // Use velocity reached callback to swing back and forth
                    // between full speed forward and full speed backward
                    function (velocity) {
                        if(velocity == 32767) {
                            textArea.value += 'Velocity: Full speed forward, now turning backward\n';
                            dc.setVelocity(-32767);
                        }
                        else if(velocity === -32767) {
                            textArea.value += 'Velocity: Full speed backward, now turning forward\n';
                            dc.setVelocity(32767);
                        }
                        else {
                            textArea.value += 'Error\n'; // Can only happen if another program sets velocity
                        }
                        textArea.scrollTop = textArea.scrollHeight;
                    }
                );
            }
        </script>
    </body>
</html>

API

Generally, every method of the JavaScript bindings can take two optional parameters, returnCallback and errorCallback. These are two user defined callback functions. The returnCallback is called with the return values as parameters, if the method returns something. The errorCallback is called with an error code in case of an error. The error code can be one of the following values:

  • IPConnection.ERROR_ALREADY_CONNECTED = 11
  • IPConnection.ERROR_NOT_CONNECTED = 12
  • IPConnection.ERROR_CONNECT_FAILED = 13
  • IPConnection.ERROR_INVALID_FUNCTION_ID = 21
  • IPConnection.ERROR_TIMEOUT = 31
  • IPConnection.ERROR_INVALID_PARAMETER = 41
  • IPConnection.ERROR_FUNCTION_NOT_SUPPORTED = 42
  • IPConnection.ERROR_UNKNOWN_ERROR = 43

The namespace for the JavaScript bindings is Tinkerforge.*.

Basic Functions

new BrickDC(uid, ipcon)
Parameters:
  • uid -- string
  • ipcon -- IPConnection

Creates an object with the unique device ID uid:

var dc = new BrickDC("YOUR_DEVICE_UID", ipcon);

This object can then be used after the IP Connection is connected (see examples above).

BrickDC.setVelocity(velocity[, returnCallback][, errorCallback])
Parameters:
  • velocity -- int
Callback:

undefined

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 setAcceleration()), 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 setPWMFrequency().

The default velocity is 0.

BrickDC.getVelocity([returnCallback][, errorCallback])
Callback:
  • velocity -- int

Returns the velocity as set by setVelocity().

BrickDC.getCurrentVelocity([returnCallback][, errorCallback])
Callback:
  • velocity -- int

Returns the current velocity of the motor. This value is different from getVelocity() whenever the motor is currently accelerating to a goal set by setVelocity().

BrickDC.setAcceleration(acceleration[, returnCallback][, errorCallback])
Parameters:
  • acceleration -- int
Callback:

undefined

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.

The default acceleration is 10000.

BrickDC.getAcceleration([returnCallback][, errorCallback])
Callback:
  • acceleration -- int

Returns the acceleration as set by setAcceleration().

BrickDC.fullBrake([returnCallback][, errorCallback])
Callback:undefined

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 setVelocity() with 0 if you just want to stop the motor.

BrickDC.enable([returnCallback][, errorCallback])
Callback:undefined

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

BrickDC.disable([returnCallback][, errorCallback])
Callback:undefined

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

BrickDC.isEnabled([returnCallback][, errorCallback])
Callback:
  • enabled -- boolean

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

Advanced Functions

BrickDC.setPWMFrequency(frequency[, returnCallback][, errorCallback])
Parameters:
  • frequency -- int
Callback:

undefined

Sets the frequency (in Hz) of the PWM with which the motor is driven. The possible range of the frequency is 1-20000Hz. 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.

The default frequency is 15 kHz.

BrickDC.getPWMFrequency([returnCallback][, errorCallback])
Callback:
  • frequency -- int

Returns the PWM frequency (in Hz) as set by setPWMFrequency().

BrickDC.getStackInputVoltage([returnCallback][, errorCallback])
Callback:
  • voltage -- int

Returns the stack input voltage in mV. 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.

BrickDC.getExternalInputVoltage([returnCallback][, errorCallback])
Callback:
  • voltage -- int

Returns the external input voltage in mV. 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.

BrickDC.getCurrentConsumption([returnCallback][, errorCallback])
Callback:
  • voltage -- int

Returns the current consumption of the motor in mA.

BrickDC.setDriveMode(mode[, returnCallback][, errorCallback])
Parameters:
  • mode -- int
Callback:

undefined

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.

The default value is 0 = Drive/Brake.

The following constants are available for this function:

  • BrickDC.DRIVE_MODE_DRIVE_BRAKE = 0
  • BrickDC.DRIVE_MODE_DRIVE_COAST = 1
BrickDC.getDriveMode([returnCallback][, errorCallback])
Callback:
  • mode -- int

Returns the drive mode, as set by setDriveMode().

The following constants are available for this function:

  • BrickDC.DRIVE_MODE_DRIVE_BRAKE = 0
  • BrickDC.DRIVE_MODE_DRIVE_COAST = 1
BrickDC.getAPIVersion()
Return type:[int, int, int]

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

BrickDC.getResponseExpected(functionId[, errorCallback])
Parameters:
  • functionId -- int
Return type:

boolean

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by setResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See setResponseExpected() for the list of function ID constants available for this function.

BrickDC.setResponseExpected(functionId, responseExpected[, errorCallback])
Parameters:
  • functionId -- int
  • responseExpected -- boolean

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID constants are available for this function:

  • BrickDC.FUNCTION_SET_VELOCITY = 1
  • BrickDC.FUNCTION_SET_ACCELERATION = 4
  • BrickDC.FUNCTION_SET_PWM_FREQUENCY = 6
  • BrickDC.FUNCTION_FULL_BRAKE = 8
  • BrickDC.FUNCTION_ENABLE = 12
  • BrickDC.FUNCTION_DISABLE = 13
  • BrickDC.FUNCTION_SET_MINIMUM_VOLTAGE = 15
  • BrickDC.FUNCTION_SET_DRIVE_MODE = 17
  • BrickDC.FUNCTION_SET_CURRENT_VELOCITY_PERIOD = 19
  • BrickDC.FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickDC.FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickDC.FUNCTION_ENABLE_STATUS_LED = 238
  • BrickDC.FUNCTION_DISABLE_STATUS_LED = 239
  • BrickDC.FUNCTION_RESET = 243
BrickDC.setResponseExpectedAll(responseExpected)
Parameters:
  • responseExpected -- boolean

Changes the response expected flag for all setter and callback configuration functions of this device at once.

BrickDC.setSPITFPBaudrateConfig(enableDynamicBaudrate, minimumDynamicBaudrate[, returnCallback][, errorCallback])
Parameters:
  • enableDynamicBaudrate -- boolean
  • minimumDynamicBaudrate -- int
Callback:

undefined

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 send/received and decreased linearly if little data is send/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 setSPITFPBaudrate(). If the dynamic baudrate is disabled, the baudrate as set by setSPITFPBaudrate() will be used statically.

The minimum dynamic baudrate has a value range of 400000 to 2000000 baud.

By default dynamic baudrate is enabled and the minimum dynamic baudrate is 400000.

New in version 2.3.5 (Firmware).

BrickDC.getSPITFPBaudrateConfig([returnCallback][, errorCallback])
Callback:
  • enableDynamicBaudrate -- boolean
  • minimumDynamicBaudrate -- int

Returns the baudrate config, see setSPITFPBaudrateConfig().

New in version 2.3.5 (Firmware).

BrickDC.getSendTimeoutCount(communicationMethod[, returnCallback][, errorCallback])
Parameters:
  • communicationMethod -- int
Callback:
  • timeoutCount -- int

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.

The following constants are available for this function:

  • BrickDC.COMMUNICATION_METHOD_NONE = 0
  • BrickDC.COMMUNICATION_METHOD_USB = 1
  • BrickDC.COMMUNICATION_METHOD_SPI_STACK = 2
  • BrickDC.COMMUNICATION_METHOD_CHIBI = 3
  • BrickDC.COMMUNICATION_METHOD_RS485 = 4
  • BrickDC.COMMUNICATION_METHOD_WIFI = 5
  • BrickDC.COMMUNICATION_METHOD_ETHERNET = 6
  • BrickDC.COMMUNICATION_METHOD_WIFI_V2 = 7

New in version 2.3.3 (Firmware).

BrickDC.setSPITFPBaudrate(brickletPort, baudrate[, returnCallback][, errorCallback])
Parameters:
  • brickletPort -- char
  • baudrate -- int
Callback:

undefined

Sets the baudrate for a specific Bricklet port ('a' - 'd'). The baudrate can be in the range 400000 to 2000000.

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 getSPITFPErrorCount()) you can decrease the baudrate.

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

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

The default baudrate for all ports is 1400000.

New in version 2.3.3 (Firmware).

BrickDC.getSPITFPBaudrate(brickletPort[, returnCallback][, errorCallback])
Parameters:
  • brickletPort -- char
Callback:
  • baudrate -- int

Returns the baudrate for a given Bricklet port, see setSPITFPBaudrate().

New in version 2.3.3 (Firmware).

BrickDC.getSPITFPErrorCount(brickletPort[, returnCallback][, errorCallback])
Parameters:
  • brickletPort -- char
Callback:
  • errorCountACKChecksum -- int
  • errorCountMessageChecksum -- int
  • errorCountFrame -- int
  • errorCountOverflow -- int

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.

New in version 2.3.3 (Firmware).

BrickDC.enableStatusLED([returnCallback][, errorCallback])
Callback:undefined

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.

New in version 2.3.1 (Firmware).

BrickDC.disableStatusLED([returnCallback][, errorCallback])
Callback:undefined

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.

New in version 2.3.1 (Firmware).

BrickDC.isStatusLEDEnabled([returnCallback][, errorCallback])
Callback:
  • enabled -- boolean

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

New in version 2.3.1 (Firmware).

BrickDC.getProtocol1BrickletName(port[, returnCallback][, errorCallback])
Parameters:
  • port -- char
Callback:
  • protocolVersion -- int
  • firmwareVersion -- [int, int, int]
  • name -- string

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.

BrickDC.getChipTemperature([returnCallback][, errorCallback])
Callback:
  • temperature -- int

Returns the temperature in °C/10 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.

BrickDC.reset([returnCallback][, errorCallback])
Callback:undefined

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!

BrickDC.getIdentity([returnCallback][, errorCallback])
Callback:
  • uid -- string
  • connectedUid -- string
  • position -- char
  • hardwareVersion -- [int, int, int]
  • firmwareVersion -- [int, int, int]
  • deviceIdentifier -- int

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 can be '0'-'8' (stack position).

The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.

Callback Configuration Functions

BrickDC.on(callback_id, function)
Parameters:
  • callback_id -- int
  • function -- function

Registers the given function with the given callback_id.

The available callback IDs with corresponding function signatures are listed below.

BrickDC.setMinimumVoltage(voltage[, returnCallback][, errorCallback])
Parameters:
  • voltage -- int
Callback:

undefined

Sets the minimum voltage in mV, 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.

The default value is 6V.

BrickDC.getMinimumVoltage([returnCallback][, errorCallback])
Callback:
  • voltage -- int

Returns the minimum voltage as set by setMinimumVoltage()

BrickDC.setCurrentVelocityPeriod(period[, returnCallback][, errorCallback])
Parameters:
  • period -- int
Callback:

undefined

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

The default value is 0.

BrickDC.getCurrentVelocityPeriod([returnCallback][, errorCallback])
Callback:
  • period -- int

Returns the period as set by setCurrentVelocityPeriod().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the on() function of the device object. The first parameter is the callback ID and the second parameter the callback function:

dc.on(BrickDC.CALLBACK_EXAMPLE,
    function (param) {
        console.log(param);
    }
);

The available constants with inherent number and type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

BrickDC.CALLBACK_UNDER_VOLTAGE
Parameters:
  • voltage -- int

This callback is triggered when the input voltage drops below the value set by setMinimumVoltage(). The parameter is the current voltage given in mV.

BrickDC.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, enable() has to be called to drive the motor again.

Note

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

BrickDC.CALLBACK_VELOCITY_REACHED
Parameters:
  • velocity -- int

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 setAcceleration()) 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.

BrickDC.CALLBACK_CURRENT_VELOCITY
Parameters:
  • velocity -- int

This callback is triggered with the period that is set by setCurrentVelocityPeriod(). 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.

Constants

BrickDC.DEVICE_IDENTIFIER

This constant is used to identify a DC Brick.

The getIdentity() function and the CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BrickDC.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a DC Brick.