Delphi/Lazarus - Tilt Bricklet

This is the description of the Delphi/Lazarus API bindings for the Tilt Bricklet. General information and technical specifications for the Tilt 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, BrickletTilt;

type
  TExample = class
  private
    ipcon: TIPConnection;
    t: TBrickletTilt;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

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

  { Create device object }
  t := TBrickletTilt.Create(UID, ipcon);

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

  { Get current tilt state }
  state := t.GetTiltState;

  if (state = BRICKLET_TILT_TILT_STATE_CLOSED) then begin
    WriteLn('Tilt State: Closed');
  end
  else if (state = BRICKLET_TILT_TILT_STATE_OPEN) then begin
    WriteLn('Tilt State: Open');
  end
  else if (state = BRICKLET_TILT_TILT_STATE_CLOSED_VIBRATING) then begin
    WriteLn('Tilt State: Closed Vibrating');
  end;

  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, BrickletTilt;

type
  TExample = class
  private
    ipcon: TIPConnection;
    t: TBrickletTilt;
  public
    procedure TiltStateCB(sender: TBrickletTilt; const state: byte);
    procedure Execute;
  end;

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

var
  e: TExample;

{ Callback procedure for tilt state callback }
procedure TExample.TiltStateCB(sender: TBrickletTilt; const state: byte);
begin
  if (state = BRICKLET_TILT_TILT_STATE_CLOSED) then begin
    WriteLn('Tilt State: Closed');
  end
  else if (state = BRICKLET_TILT_TILT_STATE_OPEN) then begin
    WriteLn('Tilt State: Open');
  end
  else if (state = BRICKLET_TILT_TILT_STATE_CLOSED_VIBRATING) then begin
    WriteLn('Tilt State: Closed Vibrating');
  end;
end;

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

  { Create device object }
  t := TBrickletTilt.Create(UID, ipcon);

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

  { Enable tilt state callback }
  t.EnableTiltStateCallback;

  { Register tilt state callback to procedure TiltStateCB }
  t.OnTiltState := {$ifdef FPC}@{$endif}TiltStateCB;

  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 TBrickletTilt.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

tilt := TBrickletTilt.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletTilt.GetTiltState: byte

Returns the current tilt state. The state can either be

  • 0 = Closed: The ball in the tilt switch closes the circuit.
  • 1 = Open: The ball in the tilt switch does not close the circuit.
  • 2 = Closed Vibrating: The tilt switch is in motion (rapid change between open and close).
Tilt states

The following constants are available for this function:

  • BRICKLET_TILT_TILT_STATE_CLOSED = 0
  • BRICKLET_TILT_TILT_STATE_OPEN = 1
  • BRICKLET_TILT_TILT_STATE_CLOSED_VIBRATING = 2

Advanced Functions

function TBrickletTilt.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 TBrickletTilt.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 TBrickletTilt.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_TILT_FUNCTION_ENABLE_TILT_STATE_CALLBACK = 2
  • BRICKLET_TILT_FUNCTION_DISABLE_TILT_STATE_CALLBACK = 3
procedure TBrickletTilt.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletTilt.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 TBrickletTilt.EnableTiltStateCallback

Enables the OnTiltState callback.

procedure TBrickletTilt.DisableTiltStateCallback

Disables the OnTiltState callback.

function TBrickletTilt.IsTiltStateCallbackEnabled: boolean

Returns true if the OnTiltState callback is enabled.

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

tilt.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 TBrickletTilt.OnTiltState
procedure(sender: TBrickletTilt; const state: byte) of object;

This callback provides the current tilt state. It is called every time the state changes.

See GetTiltState for a description of the states.

The following constants are available for this function:

  • BRICKLET_TILT_TILT_STATE_CLOSED = 0
  • BRICKLET_TILT_TILT_STATE_OPEN = 1
  • BRICKLET_TILT_TILT_STATE_CLOSED_VIBRATING = 2

Constants

const BRICKLET_TILT_DEVICE_IDENTIFIER

This constant is used to identify a Tilt 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_TILT_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Tilt Bricklet.