JavaScript - Servo Brick

This is the description of the JavaScript API bindings for the Servo Brick. General information and technical specifications for the Servo 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 Servo Brick

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var servo = new Tinkerforge.BrickServo(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) {
        // Configure two servos with voltage 5.5V
        // Servo 1: Connected to port 0, period of 19.5ms, pulse width of 1 to 2ms
        //          and operating angle -100 to 100°
        //
        // Servo 2: Connected to port 5, period of 20ms, pulse width of 0.95
        //          to 1.95ms and operating angle -90 to 90°
        servo.setOutputVoltage(5500);

        servo.setDegree(0, -10000, 10000);
        servo.setPulseWidth(0, 1000, 2000);
        servo.setPeriod(0, 19500);
        servo.setAcceleration(0, 1000); // Slow acceleration
        servo.setVelocity(0, 65535); // Full speed

        servo.setDegree(5, -9000, 9000);
        servo.setPulseWidth(5, 950, 1950);
        servo.setPeriod(5, 20000);
        servo.setAcceleration(5, 65535); // Full acceleration
        servo.setVelocity(5, 65535); // Full speed

        servo.setPosition(0, 10000); // Set to most right position
        servo.enable(0);

        servo.setPosition(5, -9000); // Set to most left position
        servo.enable(5);
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        servo.disable(0);
        servo.disable(5);
        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 Servo Brick

var ipcon = new Tinkerforge.IPConnection(); // Create IP connection
var servo = new Tinkerforge.BrickServo(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) {
        // Enable position reached callback
        servo.enablePositionReachedCallback();

        // Set velocity to 100°/s. This has to be smaller or equal to the
        // maximum velocity of the servo you are using, otherwise the position
        // reached callback will be called too early
        servo.setVelocity(0, 10000);
        servo.setPosition(0, 9000);
        servo.enable(0);
    }
);

// Register position reached callback
servo.on(Tinkerforge.BrickServo.CALLBACK_POSITION_REACHED,
    // Use position reached callback to swing back and forth
    function (servoNum, position) {
        if(position === 9000) {
            console.log('Position: 90°, going to -90°');
            servo.setPosition(servoNum, -9000);
        }
        else if(position === -9000) {
            console.log('Position: -90°, going to 90°');
            servo.setPosition(servoNum, 9000);
        }
        else {
            console.log('Error'); // Can only happen if another program sets position
        }
    }
);

console.log('Press key to exit');
process.stdin.on('data',
    function (data) {
        servo.disable(0);
        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>Servo 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 servo = new Tinkerforge.BrickServo(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) {
                        // Configure two servos with voltage 5.5V
                        // Servo 1: Connected to port 0, period of 19.5ms, pulse width of 1 to 2ms
                        //          and operating angle -100 to 100°
                        //
                        // Servo 2: Connected to port 5, period of 20ms, pulse width of 0.95
                        //          to 1.95ms and operating angle -90 to 90°
                        servo.setOutputVoltage(5500);

                        servo.setDegree(0, -10000, 10000);
                        servo.setPulseWidth(0, 1000, 2000);
                        servo.setPeriod(0, 19500);
                        servo.setAcceleration(0, 1000); // Slow acceleration
                        servo.setVelocity(0, 65535); // Full speed

                        servo.setDegree(5, -9000, 9000);
                        servo.setPulseWidth(5, 950, 1950);
                        servo.setPeriod(5, 20000);
                        servo.setAcceleration(5, 65535); // Full acceleration
                        servo.setVelocity(5, 65535); // Full speed

                        servo.setPosition(0, 10000); // Set to most right position
                        servo.enable(0);

                        servo.setPosition(5, -9000); // Set to most left position
                        servo.enable(5);
                    }
                );
            }
        </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>Servo 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 servo = new Tinkerforge.BrickServo(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) {
                        // Enable position reached callback
                        servo.enablePositionReachedCallback();

                        // Set velocity to 100°/s. This has to be smaller or equal to the
                        // maximum velocity of the servo you are using, otherwise the position
                        // reached callback will be called too early
                        servo.setVelocity(0, 10000);
                        servo.setPosition(0, 9000);
                        servo.enable(0);
                    }
                );

                // Register position reached callback
                servo.on(Tinkerforge.BrickServo.CALLBACK_POSITION_REACHED,
                    // Use position reached callback to swing back and forth
                    function (servoNum, position) {
                        if(position === 9000) {
                            textArea.value += 'Position: 90°, going to -90°\n';
                            servo.setPosition(servoNum, -9000);
                        }
                        else if(position === -9000) {
                            textArea.value += 'Position: -90°, going to 90°\n';
                            servo.setPosition(servoNum, 9000);
                        }
                        else {
                            textArea.value += 'Error\n'; // Can only happen if another program sets position
                        }
                        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.*.

Every function of the Servo Brick API that has a servo_num parameter can address a servo with the servo number (0 to 6). If it is a setter function then multiple servos can be addressed at once with a bitmask for the servos, if the highest bit is set. For example: 1 will address servo 1, (1 << 1) | (1 << 5) | (1 << 7) will address servos 1 and 5, 0xFF will address all seven servos, etc. This allows to set configurations to several servos with one function call. It is guaranteed that the changes will take effect in the same PWM period for all servos you specified in the bitmask.

Basic Functions

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

Creates an object with the unique device ID uid:

var servo = new BrickServo("YOUR_DEVICE_UID", ipcon);

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

BrickServo.enable(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:

undefined

Enables a servo (0 to 6). If a servo is enabled, the configured position, velocity, acceleration, etc. are applied immediately.

BrickServo.disable(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:

undefined

Disables a servo (0 to 6). Disabled servos are not driven at all, i.e. a disabled servo will not hold its position if a load is applied.

BrickServo.isEnabled(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • enabled -- boolean

Returns true if the specified servo is enabled, false otherwise.

BrickServo.setPosition(servoNum, position[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
  • position -- int
Callback:

undefined

Sets the position in °/100 for the specified servo.

The default range of the position is -9000 to 9000, but it can be specified according to your servo with setDegree().

If you want to control a linear servo or RC brushless motor controller or similar with the Servo Brick, you can also define lengths or speeds with setDegree().

BrickServo.getPosition(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • position -- int

Returns the position of the specified servo as set by setPosition().

BrickServo.getCurrentPosition(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • position -- int

Returns the current position of the specified servo. This may not be the value of setPosition() if the servo is currently approaching a position goal.

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

undefined

Sets the maximum velocity of the specified servo in °/100s. The velocity is accelerated according to the value set by setAcceleration().

The minimum velocity is 0 (no movement) and the maximum velocity is 65535. With a value of 65535 the position will be set immediately (no velocity).

The default value is 65535.

BrickServo.getVelocity(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • velocity -- int

Returns the velocity of the specified servo as set by setVelocity().

BrickServo.getCurrentVelocity(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • velocity -- int

Returns the current velocity of the specified servo. This may not be the value of setVelocity() if the servo is currently approaching a velocity goal.

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

undefined

Sets the acceleration of the specified servo in °/100s².

The minimum acceleration is 1 and the maximum acceleration is 65535. With a value of 65535 the velocity will be set immediately (no acceleration).

The default value is 65535.

BrickServo.getAcceleration(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • acceleration -- int

Returns the acceleration for the specified servo as set by setAcceleration().

BrickServo.setOutputVoltage(voltage[, returnCallback][, errorCallback])
Parameters:
  • voltage -- int
Callback:

undefined

Sets the output voltages with which the servos are driven in mV. The minimum output voltage is 2000mV and the maximum output voltage is 9000mV.

Note

We recommend that you set this value to the maximum voltage that is specified for your servo, most servos achieve their maximum force only with high voltages.

The default value is 5000.

BrickServo.getOutputVoltage([returnCallback][, errorCallback])
Callback:
  • voltage -- int

Returns the output voltage as specified by setOutputVoltage().

BrickServo.setPulseWidth(servoNum, min, max[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
  • min -- int
  • max -- int
Callback:

undefined

Sets the minimum and maximum pulse width of the specified servo in µs.

Usually, servos are controlled with a PWM, whereby the length of the pulse controls the position of the servo. Every servo has different minimum and maximum pulse widths, these can be specified with this function.

If you have a datasheet for your servo that specifies the minimum and maximum pulse width, you should set the values accordingly. If your servo comes without any datasheet you have to find the values via trial and error.

Both values have a range from 1 to 65535 (unsigned 16-bit integer). The minimum must be smaller than the maximum.

The default values are 1000µs (1ms) and 2000µs (2ms) for minimum and maximum pulse width.

BrickServo.getPulseWidth(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • min -- int
  • max -- int

Returns the minimum and maximum pulse width for the specified servo as set by setPulseWidth().

BrickServo.setDegree(servoNum, min, max[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
  • min -- int
  • max -- int
Callback:

undefined

Sets the minimum and maximum degree for the specified servo (by default given as °/100).

This only specifies the abstract values between which the minimum and maximum pulse width is scaled. For example: If you specify a pulse width of 1000µs to 2000µs and a degree range of -90° to 90°, a call of setPosition() with 0 will result in a pulse width of 1500µs (-90° = 1000µs, 90° = 2000µs, etc.).

Possible usage:

  • The datasheet of your servo specifies a range of 200° with the middle position at 110°. In this case you can set the minimum to -9000 and the maximum to 11000.
  • You measure a range of 220° on your servo and you don't have or need a middle position. In this case you can set the minimum to 0 and the maximum to 22000.
  • You have a linear servo with a drive length of 20cm, In this case you could set the minimum to 0 and the maximum to 20000. Now you can set the Position with setPosition() with a resolution of cm/100. Also the velocity will have a resolution of cm/100s and the acceleration will have a resolution of cm/100s².
  • You don't care about units and just want the highest possible resolution. In this case you should set the minimum to -32767 and the maximum to 32767.
  • You have a brushless motor with a maximum speed of 10000 rpm and want to control it with a RC brushless motor controller. In this case you can set the minimum to 0 and the maximum to 10000. setPosition() now controls the rpm.

Both values have a possible range from -32767 to 32767 (signed 16-bit integer). The minimum must be smaller than the maximum.

The default values are -9000 and 9000 for the minimum and maximum degree.

BrickServo.getDegree(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • min -- int
  • max -- int

Returns the minimum and maximum degree for the specified servo as set by setDegree().

BrickServo.setPeriod(servoNum, period[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
  • period -- int
Callback:

undefined

Sets the period of the specified servo in µs.

Usually, servos are controlled with a PWM. Different servos expect PWMs with different periods. Most servos run well with a period of about 20ms.

If your servo comes with a datasheet that specifies a period, you should set it accordingly. If you don't have a datasheet and you have no idea what the correct period is, the default value (19.5ms) will most likely work fine.

The minimum possible period is 1µs and the maximum is 65535µs.

The default value is 19.5ms (19500µs).

BrickServo.getPeriod(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • period -- int

Returns the period for the specified servo as set by setPeriod().

BrickServo.getServoCurrent(servoNum[, returnCallback][, errorCallback])
Parameters:
  • servoNum -- int
Callback:
  • current -- int

Returns the current consumption of the specified servo in mA.

BrickServo.getOverallCurrent([returnCallback][, errorCallback])
Callback:
  • current -- int

Returns the current consumption of all servos together in mA.

BrickServo.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.

BrickServo.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 Servo Brick.

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

Warning

This means, if you have a high stack voltage and a low external voltage, the motors 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

Advanced Functions

BrickServo.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.

BrickServo.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.

BrickServo.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:

  • BrickServo.FUNCTION_ENABLE = 1
  • BrickServo.FUNCTION_DISABLE = 2
  • BrickServo.FUNCTION_SET_POSITION = 4
  • BrickServo.FUNCTION_SET_VELOCITY = 7
  • BrickServo.FUNCTION_SET_ACCELERATION = 10
  • BrickServo.FUNCTION_SET_OUTPUT_VOLTAGE = 12
  • BrickServo.FUNCTION_SET_PULSE_WIDTH = 14
  • BrickServo.FUNCTION_SET_DEGREE = 16
  • BrickServo.FUNCTION_SET_PERIOD = 18
  • BrickServo.FUNCTION_SET_MINIMUM_VOLTAGE = 24
  • BrickServo.FUNCTION_ENABLE_POSITION_REACHED_CALLBACK = 29
  • BrickServo.FUNCTION_DISABLE_POSITION_REACHED_CALLBACK = 30
  • BrickServo.FUNCTION_ENABLE_VELOCITY_REACHED_CALLBACK = 32
  • BrickServo.FUNCTION_DISABLE_VELOCITY_REACHED_CALLBACK = 33
  • BrickServo.FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BrickServo.FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BrickServo.FUNCTION_ENABLE_STATUS_LED = 238
  • BrickServo.FUNCTION_DISABLE_STATUS_LED = 239
  • BrickServo.FUNCTION_RESET = 243
BrickServo.setResponseExpectedAll(responseExpected)
Parameters:
  • responseExpected -- boolean

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

BrickServo.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 2.3.4 (Firmware).

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

Returns the baudrate config, see setSPITFPBaudrateConfig().

New in version 2.3.4 (Firmware).

BrickServo.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:

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

New in version 2.3.2 (Firmware).

BrickServo.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 2.3.2 (Firmware).

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

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

New in version 2.3.2 (Firmware).

BrickServo.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 2.3.2 (Firmware).

BrickServo.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).

BrickServo.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).

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

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

New in version 2.3.1 (Firmware).

BrickServo.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.

BrickServo.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.

BrickServo.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!

BrickServo.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

BrickServo.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.

BrickServo.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 Servo Brick is 5V. You can use this function to detect the discharge of a battery that is used to drive the stepper motor. If you have a fixed power supply, you likely do not need this functionality.

The default value is 5V (5000mV).

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

Returns the minimum voltage as set by setMinimumVoltage()

BrickServo.enablePositionReachedCallback([returnCallback][, errorCallback])
Callback:undefined

Enables the CALLBACK_POSITION_REACHED callback.

Default is disabled.

New in version 2.0.1 (Firmware).

BrickServo.disablePositionReachedCallback([returnCallback][, errorCallback])
Callback:undefined

Disables the CALLBACK_POSITION_REACHED callback.

Default is disabled.

New in version 2.0.1 (Firmware).

BrickServo.isPositionReachedCallbackEnabled([returnCallback][, errorCallback])
Callback:
  • enabled -- boolean

Returns true if CALLBACK_POSITION_REACHED callback is enabled, false otherwise.

New in version 2.0.1 (Firmware).

BrickServo.enableVelocityReachedCallback([returnCallback][, errorCallback])
Callback:undefined

Enables the CALLBACK_VELOCITY_REACHED callback.

Default is disabled.

New in version 2.0.1 (Firmware).

BrickServo.disableVelocityReachedCallback([returnCallback][, errorCallback])
Callback:undefined

Disables the CALLBACK_VELOCITY_REACHED callback.

Default is disabled.

New in version 2.0.1 (Firmware).

BrickServo.isVelocityReachedCallbackEnabled([returnCallback][, errorCallback])
Callback:
  • enabled -- boolean

Returns true if CALLBACK_VELOCITY_REACHED callback is enabled, false otherwise.

New in version 2.0.1 (Firmware).

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:

servo.on(BrickServo.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.

BrickServo.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.

BrickServo.CALLBACK_POSITION_REACHED
Parameters:
  • servoNum -- int
  • position -- int

This callback is triggered when a position set by setPosition() is reached. If the new position matches the current position then the callback is not triggered, because the servo didn't move. The parameters are the servo and the position that is reached.

You can enable this callback with enablePositionReachedCallback().

Note

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

BrickServo.CALLBACK_VELOCITY_REACHED
Parameters:
  • servoNum -- int
  • velocity -- int

This callback is triggered when a velocity set by setVelocity() is reached. The parameters are the servo and the velocity that is reached.

You can enable this callback with enableVelocityReachedCallback().

Note

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

Constants

BrickServo.DEVICE_IDENTIFIER

This constant is used to identify a Servo 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.

BrickServo.DEVICE_DISPLAY_NAME

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