Delphi/Lazarus - Servo Brick

This is the description of the Delphi/Lazarus 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 Delphi/Lazarus API bindings is part of their general description.

Examples

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

Configuration

Download (ExampleConfiguration.pas)

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program ExampleConfiguration;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickServo;

type
  TExample = class
  private
    ipcon: TIPConnection;
    servo: TBrickServo;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XXYYZZ'; { Change XXYYZZ to the UID of your Servo Brick }

var
  e: TExample;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  servo := TBrickServo.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { 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);

  WriteLn('Press key to exit');
  ReadLn;

  servo.Disable(0);
  servo.Disable(5);

  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

Callback

Download (ExampleCallback.pas)

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program ExampleCallback;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickServo;

type
  TExample = class
  private
    ipcon: TIPConnection;
    servo: TBrickServo;
  public
    procedure PositionReachedCB(sender: TBrickServo; const servoNum: byte;
                                const position: smallint);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XXYYZZ'; { Change XXYYZZ to the UID of your Servo Brick }

var
  e: TExample;

{ Use position reached callback to swing back and forth }
procedure TExample.PositionReachedCB(sender: TBrickServo; const servoNum: byte;
                                     const position: smallint);
begin
  if (position = 9000) then begin
    WriteLn('Position: 90°, going to -90°');
    sender.SetPosition(servoNum, -9000);
  end
  else if (position = -9000) then begin
    WriteLn('Position: -90°, going to 90°');
    sender.SetPosition(servoNum, 9000);
  end
  else begin
    WriteLn('Error'); { Can only happen if another program sets position }
  end;
end;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  servo := TBrickServo.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { Register position reached callback to procedure PositionReachedCB }
  servo.OnPositionReached := {$ifdef FPC}@{$endif}PositionReachedCB;

  { 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);

  WriteLn('Press key to exit');
  ReadLn;

  servo.Disable(0);

  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

API

Since Delphi does not support multiple return values directly, we use the out keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

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

constructor TBrickServo.Create(const uid: string; ipcon: TIPConnection)
Parameters:
  • uid – Type: string
  • ipcon – Type: TIPConnection
Returns:
  • servo – Type: TBrickServo

Creates an object with the unique device ID uid:

servo := TBrickServo.Create('YOUR_DEVICE_UID', ipcon);

This object can then be used after the IP Connection is connected.

procedure TBrickServo.Enable(const servoNum: byte)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]

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

procedure TBrickServo.Disable(const servoNum: byte)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]

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.

function TBrickServo.IsEnabled(const servoNum: byte): boolean
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • enabled – Type: boolean, Default: false

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

procedure TBrickServo.SetPosition(const servoNum: byte; const position: smallint)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • position – Type: smallint, Unit: 1/100 °, Range: ?

Sets the position 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.

function TBrickServo.GetPosition(const servoNum: byte): smallint
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • position – Type: smallint, Unit: 1/100 °, Range: ?

Returns the position of the specified servo as set by SetPosition.

function TBrickServo.GetCurrentPosition(const servoNum: byte): smallint
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • position – Type: smallint, Unit: 1/100 °, Range: ?

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.

procedure TBrickServo.SetVelocity(const servoNum: byte; const velocity: word)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • velocity – Type: word, Unit: 1/100 °/s, Range: [0 to 216 - 1], Default: 216 - 1

Sets the maximum velocity of the specified servo. 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).

function TBrickServo.GetVelocity(const servoNum: byte): word
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • velocity – Type: word, Unit: 1/100 °/s, Range: [0 to 216 - 1], Default: 216 - 1

Returns the velocity of the specified servo as set by SetVelocity.

function TBrickServo.GetCurrentVelocity(const servoNum: byte): word
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • velocity – Type: word, Unit: 1/100 °/s, Range: [0 to 216 - 1], Default: 216 - 1

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.

procedure TBrickServo.SetAcceleration(const servoNum: byte; const acceleration: word)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • acceleration – Type: word, Unit: 1/100 °/s², Range: [0 to 216 - 1], Default: 216 - 1

Sets the acceleration of the specified servo.

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

function TBrickServo.GetAcceleration(const servoNum: byte): word
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • acceleration – Type: word, Unit: 1/100 °/s², Range: [0 to 216 - 1], Default: 216 - 1

Returns the acceleration for the specified servo as set by SetAcceleration.

procedure TBrickServo.SetOutputVoltage(const voltage: word)
Parameters:
  • voltage – Type: word, Unit: 1 mV, Range: [2000 to 9000], Default: 5000

Sets the output voltages with which the servos are driven.

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.

function TBrickServo.GetOutputVoltage: word
Returns:
  • voltage – Type: word, Unit: 1 mV, Range: [2000 to 9000], Default: 5000

Returns the output voltage as specified by SetOutputVoltage.

procedure TBrickServo.SetPulseWidth(const servoNum: byte; const min: word; const max: word)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • min – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 1000
  • max – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 2000

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

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.

The minimum must be smaller than the maximum.

procedure TBrickServo.GetPulseWidth(const servoNum: byte; out min: word; out max: word)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Output Parameters:
  • min – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 1000
  • max – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 2000

Returns the minimum and maximum pulse width for the specified servo as set by SetPulseWidth.

procedure TBrickServo.SetDegree(const servoNum: byte; const min: smallint; const max: smallint)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • min – Type: smallint, Unit: 1/100 °, Range: [-215 to 215 - 1], Default: -9000
  • max – Type: smallint, Unit: 1/100 °, Range: [-215 to 215 - 1], Default: 9000

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.

The minimum must be smaller than the maximum.

procedure TBrickServo.GetDegree(const servoNum: byte; out min: smallint; out max: smallint)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Output Parameters:
  • min – Type: smallint, Unit: 1/100 °, Range: [-215 to 215 - 1], Default: -9000
  • max – Type: smallint, Unit: 1/100 °, Range: [-215 to 215 - 1], Default: 9000

Returns the minimum and maximum degree for the specified servo as set by SetDegree.

procedure TBrickServo.SetPeriod(const servoNum: byte; const period: word)
Parameters:
  • servoNum – Type: byte, Range: [0 to 6, 128 to 255]
  • period – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 19500

Sets the period of the specified servo.

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 will most likely work fine.

function TBrickServo.GetPeriod(const servoNum: byte): word
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • period – Type: word, Unit: 1 µs, Range: [0 to 216 - 1], Default: 19500

Returns the period for the specified servo as set by SetPeriod.

function TBrickServo.GetServoCurrent(const servoNum: byte): word
Parameters:
  • servoNum – Type: byte, Range: [0 to 6]
Returns:
  • current – Type: word, Unit: 1 mA, Range: [0 to 216 - 1]

Returns the current consumption of the specified servo.

function TBrickServo.GetOverallCurrent: word
Returns:
  • current – Type: word, Unit: 1 mA, Range: [0 to 216 - 1]

Returns the current consumption of all servos together.

function TBrickServo.GetStackInputVoltage: word
Returns:
  • voltage – Type: word, Unit: 1 mV, Range: [0 to 216 - 1]

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.

function TBrickServo.GetExternalInputVoltage: word
Returns:
  • voltage – Type: word, Unit: 1 mV, Range: [0 to 216 - 1]

Returns the external input voltage. 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

procedure TBrickServo.SetSPITFPBaudrateConfig(const enableDynamicBaudrate: boolean; const minimumDynamicBaudrate: longword)
Parameters:
  • enableDynamicBaudrate – Type: boolean, Default: true
  • minimumDynamicBaudrate – Type: longword, Unit: 1 Bd, Range: [400000 to 2000000], Default: 400000

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 SetSPITFPBaudrate. If the dynamic baudrate is disabled, the baudrate as set by SetSPITFPBaudrate will be used statically.

New in version 2.3.4 (Firmware).

procedure TBrickServo.GetSPITFPBaudrateConfig(out enableDynamicBaudrate: boolean; out minimumDynamicBaudrate: longword)
Output Parameters:
  • enableDynamicBaudrate – Type: boolean, Default: true
  • minimumDynamicBaudrate – Type: longword, Unit: 1 Bd, Range: [400000 to 2000000], Default: 400000

Returns the baudrate config, see SetSPITFPBaudrateConfig.

New in version 2.3.4 (Firmware).

function TBrickServo.GetSendTimeoutCount(const communicationMethod: byte): longword
Parameters:
  • communicationMethod – Type: byte, Range: See constants
Returns:
  • timeoutCount – Type: longword, Range: [0 to 232 - 1]

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:

For communicationMethod:

  • BRICK_SERVO_COMMUNICATION_METHOD_NONE = 0
  • BRICK_SERVO_COMMUNICATION_METHOD_USB = 1
  • BRICK_SERVO_COMMUNICATION_METHOD_SPI_STACK = 2
  • BRICK_SERVO_COMMUNICATION_METHOD_CHIBI = 3
  • BRICK_SERVO_COMMUNICATION_METHOD_RS485 = 4
  • BRICK_SERVO_COMMUNICATION_METHOD_WIFI = 5
  • BRICK_SERVO_COMMUNICATION_METHOD_ETHERNET = 6
  • BRICK_SERVO_COMMUNICATION_METHOD_WIFI_V2 = 7

New in version 2.3.2 (Firmware).

procedure TBrickServo.SetSPITFPBaudrate(const brickletPort: char; const baudrate: longword)
Parameters:
  • brickletPort – Type: char, Range: ['a' to 'b']
  • baudrate – Type: longword, Unit: 1 Bd, Range: [400000 to 2000000], Default: 1400000

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 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 your applications we recommend to not change the baudrate.

New in version 2.3.2 (Firmware).

function TBrickServo.GetSPITFPBaudrate(const brickletPort: char): longword
Parameters:
  • brickletPort – Type: char, Range: ['a' to 'b']
Returns:
  • baudrate – Type: longword, Unit: 1 Bd, Range: [400000 to 2000000], Default: 1400000

Returns the baudrate for a given Bricklet port, see SetSPITFPBaudrate.

New in version 2.3.2 (Firmware).

procedure TBrickServo.GetSPITFPErrorCount(const brickletPort: char; out errorCountACKChecksum: longword; out errorCountMessageChecksum: longword; out errorCountFrame: longword; out errorCountOverflow: longword)
Parameters:
  • brickletPort – Type: char, Range: ['a' to 'b']
Output Parameters:
  • errorCountACKChecksum – Type: longword, Range: [0 to 232 - 1]
  • errorCountMessageChecksum – Type: longword, Range: [0 to 232 - 1]
  • errorCountFrame – Type: longword, Range: [0 to 232 - 1]
  • errorCountOverflow – Type: longword, Range: [0 to 232 - 1]

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).

procedure TBrickServo.EnableStatusLED

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).

procedure TBrickServo.DisableStatusLED

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).

function TBrickServo.IsStatusLEDEnabled: boolean
Returns:
  • enabled – Type: boolean, Default: true

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

New in version 2.3.1 (Firmware).

function TBrickServo.GetChipTemperature: smallint
Returns:
  • temperature – Type: smallint, Unit: 1/10 °C, Range: [-215 to 215 - 1]

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.

procedure TBrickServo.Reset

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!

procedure TBrickServo.GetIdentity(out uid: string; out connectedUid: string; out position: char; out hardwareVersion: array [0..2] of byte; out firmwareVersion: array [0..2] of byte; out deviceIdentifier: word)
Output Parameters:
  • uid – Type: string, Length: up to 8
  • connectedUid – Type: string, Length: up to 8
  • position – Type: char, Range: ['0' to '8']
  • hardwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • firmwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • deviceIdentifier – Type: word, Range: [0 to 216 - 1]

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 here. There is also a constant for the device identifier of this Brick.

Callback Configuration Functions

procedure TBrickServo.SetMinimumVoltage(const voltage: word)
Parameters:
  • voltage – Type: word, Unit: 1 mV, Range: [0 to 216 - 1], Default: 5000

Sets the minimum voltage, below which the OnUnderVoltage 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.

function TBrickServo.GetMinimumVoltage: word
Returns:
  • voltage – Type: word, Unit: 1 mV, Range: [0 to 216 - 1], Default: 5000

Returns the minimum voltage as set by SetMinimumVoltage

procedure TBrickServo.EnablePositionReachedCallback

Enables the OnPositionReached callback.

Default is disabled.

New in version 2.0.1 (Firmware).

procedure TBrickServo.DisablePositionReachedCallback

Disables the OnPositionReached callback.

New in version 2.0.1 (Firmware).

function TBrickServo.IsPositionReachedCallbackEnabled: boolean
Returns:
  • enabled – Type: boolean, Default: false

Returns true if OnPositionReached callback is enabled, false otherwise.

New in version 2.0.1 (Firmware).

procedure TBrickServo.EnableVelocityReachedCallback

Enables the OnVelocityReached callback.

Default is disabled.

New in version 2.0.1 (Firmware).

procedure TBrickServo.DisableVelocityReachedCallback

Disables the OnVelocityReached callback.

Default is disabled.

New in version 2.0.1 (Firmware).

function TBrickServo.IsVelocityReachedCallbackEnabled: boolean
Returns:
  • enabled – Type: boolean, Default: false

Returns true if OnVelocityReached 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 by assigning a procedure to an callback property of the device object:

procedure TExample.MyCallback(sender: TBrickServo; const value: longint);
begin
  WriteLn(Format('Value: %d', [value]));
end;

servo.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;

The available callback properties and their parameter types 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.

property TBrickServo.OnUnderVoltage
procedure(sender: TBrickServo; const voltage: word) of object;
Callback Parameters:
  • sender – Type: TBrickServo
  • voltage – Type: word, Unit: 1 mV, Range: [0 to 216 - 1]

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

property TBrickServo.OnPositionReached
procedure(sender: TBrickServo; const servoNum: byte; const position: smallint) of object;
Callback Parameters:
  • sender – Type: TBrickServo
  • servoNum – Type: byte, Range: [0 to 6]
  • position – Type: smallint, Unit: 1/100 °, Range: ?

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.

property TBrickServo.OnVelocityReached
procedure(sender: TBrickServo; const servoNum: byte; const velocity: smallint) of object;
Callback Parameters:
  • sender – Type: TBrickServo
  • servoNum – Type: byte, Range: [0 to 6]
  • velocity – Type: smallint, Unit: 1/100 °/s, Range: [-215 to 215 - 1]

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.

Virtual Functions

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

function TBrickServo.GetAPIVersion: array [0..2] of byte
Output Parameters:
  • apiVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]

Returns the version of the API definition 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.

function TBrickServo.GetResponseExpected(const functionId: byte): boolean
Parameters:
  • functionId – Type: byte, Range: See constants
Returns:
  • responseExpected – 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICK_SERVO_FUNCTION_ENABLE = 1
  • BRICK_SERVO_FUNCTION_DISABLE = 2
  • BRICK_SERVO_FUNCTION_SET_POSITION = 4
  • BRICK_SERVO_FUNCTION_SET_VELOCITY = 7
  • BRICK_SERVO_FUNCTION_SET_ACCELERATION = 10
  • BRICK_SERVO_FUNCTION_SET_OUTPUT_VOLTAGE = 12
  • BRICK_SERVO_FUNCTION_SET_PULSE_WIDTH = 14
  • BRICK_SERVO_FUNCTION_SET_DEGREE = 16
  • BRICK_SERVO_FUNCTION_SET_PERIOD = 18
  • BRICK_SERVO_FUNCTION_SET_MINIMUM_VOLTAGE = 24
  • BRICK_SERVO_FUNCTION_ENABLE_POSITION_REACHED_CALLBACK = 29
  • BRICK_SERVO_FUNCTION_DISABLE_POSITION_REACHED_CALLBACK = 30
  • BRICK_SERVO_FUNCTION_ENABLE_VELOCITY_REACHED_CALLBACK = 32
  • BRICK_SERVO_FUNCTION_DISABLE_VELOCITY_REACHED_CALLBACK = 33
  • BRICK_SERVO_FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BRICK_SERVO_FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BRICK_SERVO_FUNCTION_ENABLE_STATUS_LED = 238
  • BRICK_SERVO_FUNCTION_DISABLE_STATUS_LED = 239
  • BRICK_SERVO_FUNCTION_RESET = 243
  • BRICK_SERVO_FUNCTION_WRITE_BRICKLET_PLUGIN = 246
procedure TBrickServo.SetResponseExpected(const functionId: byte; const responseExpected: boolean)
Parameters:
  • functionId – Type: byte, Range: See constants
  • responseExpected – Type: 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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

  • BRICK_SERVO_FUNCTION_ENABLE = 1
  • BRICK_SERVO_FUNCTION_DISABLE = 2
  • BRICK_SERVO_FUNCTION_SET_POSITION = 4
  • BRICK_SERVO_FUNCTION_SET_VELOCITY = 7
  • BRICK_SERVO_FUNCTION_SET_ACCELERATION = 10
  • BRICK_SERVO_FUNCTION_SET_OUTPUT_VOLTAGE = 12
  • BRICK_SERVO_FUNCTION_SET_PULSE_WIDTH = 14
  • BRICK_SERVO_FUNCTION_SET_DEGREE = 16
  • BRICK_SERVO_FUNCTION_SET_PERIOD = 18
  • BRICK_SERVO_FUNCTION_SET_MINIMUM_VOLTAGE = 24
  • BRICK_SERVO_FUNCTION_ENABLE_POSITION_REACHED_CALLBACK = 29
  • BRICK_SERVO_FUNCTION_DISABLE_POSITION_REACHED_CALLBACK = 30
  • BRICK_SERVO_FUNCTION_ENABLE_VELOCITY_REACHED_CALLBACK = 32
  • BRICK_SERVO_FUNCTION_DISABLE_VELOCITY_REACHED_CALLBACK = 33
  • BRICK_SERVO_FUNCTION_SET_SPITFP_BAUDRATE_CONFIG = 231
  • BRICK_SERVO_FUNCTION_SET_SPITFP_BAUDRATE = 234
  • BRICK_SERVO_FUNCTION_ENABLE_STATUS_LED = 238
  • BRICK_SERVO_FUNCTION_DISABLE_STATUS_LED = 239
  • BRICK_SERVO_FUNCTION_RESET = 243
  • BRICK_SERVO_FUNCTION_WRITE_BRICKLET_PLUGIN = 246
procedure TBrickServo.SetResponseExpectedAll(const responseExpected: boolean)
Parameters:
  • responseExpected – Type: boolean

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

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

procedure TBrickServo.GetProtocol1BrickletName(const port: char; out protocolVersion: byte; out firmwareVersion: array [0..2] of byte; out name: string)
Parameters:
  • port – Type: char, Range: ['a' to 'b']
Output Parameters:
  • protocolVersion – Type: byte, Range: [0 to 255]
  • firmwareVersion – Type: array [0..2] of byte
    • 0: major – Type: byte, Range: [0 to 255]
    • 1: minor – Type: byte, Range: [0 to 255]
    • 2: revision – Type: byte, Range: [0 to 255]
  • name – Type: string, Length: up to 40

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.

procedure TBrickServo.WriteBrickletPlugin(const port: char; const offset: byte; const chunk: array [0..31] of byte)
Parameters:
  • port – Type: char, Range: ['a' to 'b']
  • offset – Type: byte, Range: [0 to 255]
  • chunk – Type: array [0..31] of byte, Range: [0 to 255]

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.

function TBrickServo.ReadBrickletPlugin(const port: char; const offset: byte): array [0..31] of byte
Parameters:
  • port – Type: char, Range: ['a' to 'b']
  • offset – Type: byte, Range: [0 to 255]
Returns:
  • chunk – Type: array [0..31] of byte, Range: [0 to 255]

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.

Constants

const BRICK_SERVO_DEVICE_IDENTIFIER

This constant is used to identify a Servo Brick.

The GetIdentity function and the TIPConnection.OnEnumerate callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

const BRICK_SERVO_DEVICE_DISPLAY_NAME

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