Delphi/Lazarus - Motorized Linear Poti Bricklet

This is the description of the Delphi/Lazarus API bindings for the Motorized Linear Poti Bricklet. General information and technical specifications for the Motorized Linear Poti Bricklet 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).

Simple

Download (ExampleSimple.pas)

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program ExampleSimple;

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

uses
  SysUtils, IPConnection, BrickletMotorizedLinearPoti;

type
  TExample = class
  private
    ipcon: TIPConnection;
    mlp: TBrickletMotorizedLinearPoti;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Motorized Linear Poti Bricklet }

var
  e: TExample;

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

  { Create device object }
  mlp := TBrickletMotorizedLinearPoti.Create(UID, ipcon);

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

  { Get current position }
  position := mlp.GetPosition;
  WriteLn(Format('Position: %d', [position])); { Range: 0 to 100 }

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

type
  TExample = class
  private
    ipcon: TIPConnection;
    mlp: TBrickletMotorizedLinearPoti;
  public
    procedure PositionCB(sender: TBrickletMotorizedLinearPoti; const position: word);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Motorized Linear Poti Bricklet }

var
  e: TExample;

{ Callback procedure for position callback }
procedure TExample.PositionCB(sender: TBrickletMotorizedLinearPoti; const position: word);
begin
  WriteLn(Format('Position: %d', [position])); { Range: 0 to 100 }
end;

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

  { Create device object }
  mlp := TBrickletMotorizedLinearPoti.Create(UID, ipcon);

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

  { Register position callback to procedure PositionCB }
  mlp.OnPosition := {$ifdef FPC}@{$endif}PositionCB;

  { Set period for position callback to 0.05s (50ms) without a threshold }
  mlp.SetPositionCallbackConfiguration(50, false, 'x', 0, 0);

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

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

Motor

Download (ExampleMotor.pas)

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program ExampleMotor;

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

uses
  SysUtils, IPConnection, BrickletMotorizedLinearPoti;

type
  TExample = class
  private
    ipcon: TIPConnection;
    mlp: TBrickletMotorizedLinearPoti;
  public
    procedure PositionReachedCB(sender: TBrickletMotorizedLinearPoti;
                                const position: word);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Motorized Linear Poti Bricklet }

var
  e: TExample;

{ Callback procedure for position reached callback }
procedure TExample.PositionReachedCB(sender: TBrickletMotorizedLinearPoti;
                                     const position: word);
begin
  WriteLn(Format('Position: %d', [position])); { Range: 0 to 100 }
end;

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

  { Create device object }
  mlp := TBrickletMotorizedLinearPoti.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 }
  mlp.OnPositionReached := {$ifdef FPC}@{$endif}PositionReachedCB;

  { Move slider smooth to the middle }
  mlp.SetMotorPosition(50, BRICKLET_MOTORIZED_LINEAR_POTI_DRIVE_MODE_SMOOTH, false);

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

Basic Functions

constructor TBrickletMotorizedLinearPoti.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

motorizedLinearPoti := TBrickletMotorizedLinearPoti.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletMotorizedLinearPoti.GetPosition: word

Returns the position of the linear potentiometer. The value is between 0 (slider down) and 100 (slider up).

If you want to get the value periodically, it is recommended to use the OnPosition callback. You can set the callback configuration with SetPositionCallbackConfiguration.

procedure TBrickletMotorizedLinearPoti.SetMotorPosition(const position: word; const driveMode: byte; const holdPosition: boolean)

Sets the position of the potentiometer. The motorized potentiometer will immediately start to approach the position. Depending on the chosen drive mode, the position will either be reached as fast as possible or in a slow but smooth motion.

The position has to be between 0 (slider down) and 100 (slider up).

If you set the hold position parameter to true, the position will automatically be retained. If a user changes the position of the potentiometer, it will automatically drive back to the original set point.

If the hold position parameter is set to false, the potentiometer can be changed again by the user as soon as the set point was reached once.

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_DRIVE_MODE_FAST = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_DRIVE_MODE_SMOOTH = 1
procedure TBrickletMotorizedLinearPoti.GetMotorPosition(out position: word; out driveMode: byte; out holdPosition: boolean; out positionReached: boolean)

Returns the last motor position as set by SetMotorPosition. This is not the current position (use GetPosition to get the current position). This is the last used set point and configuration.

The position reached parameter is true if the position has been reached at one point. The position may have been changed again in the meantime by the user.

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_DRIVE_MODE_FAST = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_DRIVE_MODE_SMOOTH = 1

Advanced Functions

procedure TBrickletMotorizedLinearPoti.Calibrate

Starts a calibration procedure. The potentiometer will be driven to the extreme points to calibrate the potentiometer.

The calibration is saved in flash, it does not have to be called on every start up.

The Motorized Linear Poti Bricklet is already factory-calibrated during testing at Tinkerforge.

function TBrickletMotorizedLinearPoti.GetAPIVersion: array [0..2] of byte

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.

function TBrickletMotorizedLinearPoti.GetResponseExpected(const functionId: byte): 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.

procedure TBrickletMotorizedLinearPoti.SetResponseExpected(const functionId: byte; const 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:

  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_SET_POSITION_CALLBACK_CONFIGURATION = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_SET_MOTOR_POSITION = 5
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_CALIBRATE = 7
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_SET_POSITION_REACHED_CALLBACK_CONFIGURATION = 8
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_RESET = 243
  • BRICKLET_MOTORIZED_LINEAR_POTI_FUNCTION_WRITE_UID = 248
procedure TBrickletMotorizedLinearPoti.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletMotorizedLinearPoti.GetSPITFPErrorCount(out errorCountAckChecksum: longword; out errorCountMessageChecksum: longword; out errorCountFrame: longword; out errorCountOverflow: longword)

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 Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

function TBrickletMotorizedLinearPoti.SetBootloaderMode(const mode: byte): byte

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

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

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_OK = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_INVALID_MODE = 1
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_NO_CHANGE = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_STATUS_CRC_MISMATCH = 5
function TBrickletMotorizedLinearPoti.GetBootloaderMode: byte

Returns the current bootloader mode, see SetBootloaderMode.

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_MOTORIZED_LINEAR_POTI_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
procedure TBrickletMotorizedLinearPoti.SetWriteFirmwarePointer(const pointer: longword)

Sets the firmware pointer for WriteFirmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

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

function TBrickletMotorizedLinearPoti.WriteFirmware(const data: array [0..63] of byte): byte

Writes 64 Bytes of firmware at the position as written by SetWriteFirmwarePointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

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

procedure TBrickletMotorizedLinearPoti.SetStatusLEDConfig(const config: byte)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletMotorizedLinearPoti.GetStatusLEDConfig: byte

Returns the configuration as set by SetStatusLEDConfig

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_MOTORIZED_LINEAR_POTI_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletMotorizedLinearPoti.GetChipTemperature: smallint

Returns the temperature in °C 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 bad accuracy. Practically it is only useful as an indicator for temperature changes.

procedure TBrickletMotorizedLinearPoti.Reset

Calling this function will reset the Bricklet. All configurations will be lost.

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

procedure TBrickletMotorizedLinearPoti.WriteUID(const uid: longword)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

function TBrickletMotorizedLinearPoti.ReadUID: longword

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

procedure TBrickletMotorizedLinearPoti.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)

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

The position can be 'a', 'b', 'c' or 'd'.

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

Callback Configuration Functions

procedure TBrickletMotorizedLinearPoti.SetPositionCallbackConfiguration(const period: longword; const valueHasToChange: boolean; const option: char; const min: word; const max: word)

The period in ms is the period with which the OnPosition callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the OnPosition callback.

The following options are possible:

Option Description
'x' Threshold is turned off
'o' Threshold is triggered when the value is outside the min and max values
'i' Threshold is triggered when the value is inside or equal to the min and max values
'<' Threshold is triggered when the value is smaller than the min value (max is ignored)
'>' Threshold is triggered when the value is greater than the min value (max is ignored)

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The default value is (0, false, 'x', 0, 0).

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletMotorizedLinearPoti.GetPositionCallbackConfiguration(out period: longword; out valueHasToChange: boolean; out option: char; out min: word; out max: word)

Returns the callback configuration as set by SetPositionCallbackConfiguration.

The following constants are available for this function:

  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_MOTORIZED_LINEAR_POTI_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletMotorizedLinearPoti.SetPositionReachedCallbackConfiguration(const enabled: boolean)

Enables/Disables OnPositionReached callback.

By default the callback is enabled.

function TBrickletMotorizedLinearPoti.GetPositionReachedCallbackConfiguration: boolean

Returns the OnPositionReached callback configuration as set by SetPositionReachedCallbackConfiguration.

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: TBrickletMotorizedLinearPoti; const param: word);
begin
  WriteLn(param);
end;

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

The available callback property and their 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.

property TBrickletMotorizedLinearPoti.OnPosition
procedure(sender: TBrickletMotorizedLinearPoti; const position: word) of object;

This callback is triggered periodically according to the configuration set by SetPositionCallbackConfiguration.

The parameter is the same as GetPosition.

property TBrickletMotorizedLinearPoti.OnPositionReached
procedure(sender: TBrickletMotorizedLinearPoti; const position: word) of object;

This callback is triggered if a new position as set by SetMotorPosition is reached.

The parameter is the current position.

Constants

const BRICKLET_MOTORIZED_LINEAR_POTI_DEVICE_IDENTIFIER

This constant is used to identify a Motorized Linear Poti Bricklet.

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

const BRICKLET_MOTORIZED_LINEAR_POTI_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Motorized Linear Poti Bricklet.