Delphi/Lazarus - Rotary Encoder Bricklet

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

type
  TExample = class
  private
    ipcon: TIPConnection;
    re: TBrickletRotaryEncoder;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

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

  { Create device object }
  re := TBrickletRotaryEncoder.Create(UID, ipcon);

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

  { Get current count without reset }
  count := re.GetCount(false);
  WriteLn(Format('Count: %d', [count]));

  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, BrickletRotaryEncoder;

type
  TExample = class
  private
    ipcon: TIPConnection;
    re: TBrickletRotaryEncoder;
  public
    procedure CountCB(sender: TBrickletRotaryEncoder; const count: longint);
    procedure Execute;
  end;

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

var
  e: TExample;

{ Callback procedure for count callback }
procedure TExample.CountCB(sender: TBrickletRotaryEncoder; const count: longint);
begin
  WriteLn(Format('Count: %d', [count]));
end;

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

  { Create device object }
  re := TBrickletRotaryEncoder.Create(UID, ipcon);

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

  { Register count callback to procedure CountCB }
  re.OnCount := {$ifdef FPC}@{$endif}CountCB;

  { Set period for count callback to 0.05s (50ms)
    Note: The count callback is only called every 0.05 seconds
          if the count has changed since the last call! }
  re.SetCountCallbackPeriod(50);

  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 TBrickletRotaryEncoder.Create(const uid: string; ipcon: TIPConnection)
Parameters:
  • uid – Type: string
  • ipcon – Type: TIPConnection
Returns:
  • rotaryEncoder – Type: TBrickletRotaryEncoder

Creates an object with the unique device ID uid:

rotaryEncoder := TBrickletRotaryEncoder.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletRotaryEncoder.GetCount(const reset: boolean): longint
Parameters:
  • reset – Type: boolean
Returns:
  • count – Type: longint, Range: [-231 to 231 - 1]

Returns the current count of the encoder. If you set reset to true, the count is set back to 0 directly after the current count is read.

The encoder has 24 steps per rotation

Turning the encoder to the left decrements the counter, so a negative count is possible.

function TBrickletRotaryEncoder.IsPressed: boolean
Returns:
  • pressed – Type: boolean

Returns true if the button is pressed and false otherwise.

It is recommended to use the OnPressed and OnReleased callbacks to handle the button.

Advanced Functions

procedure TBrickletRotaryEncoder.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: ['a' to 'h', 'z']
  • 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 Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always as position 'z'.

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

Callback Configuration Functions

procedure TBrickletRotaryEncoder.SetCountCallbackPeriod(const period: longword)
Parameters:
  • period – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Sets the period with which the OnCount callback is triggered periodically. A value of 0 turns the callback off.

The OnCount callback is only triggered if the count has changed since the last triggering.

function TBrickletRotaryEncoder.GetCountCallbackPeriod: longword
Returns:
  • period – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetCountCallbackPeriod.

procedure TBrickletRotaryEncoder.SetCountCallbackThreshold(const option: char; const min: longint; const max: longint)
Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: longint, Range: [-231 to 231 - 1], Default: 0
  • max – Type: longint, Range: [-231 to 231 - 1], Default: 0

Sets the thresholds for the OnCountReached callback.

The following options are possible:

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

The following constants are available for this function:

For option:

  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletRotaryEncoder.GetCountCallbackThreshold(out option: char; out min: longint; out max: longint)
Output Parameters:
  • option – Type: char, Range: See constants, Default: 'x'
  • min – Type: longint, Range: [-231 to 231 - 1], Default: 0
  • max – Type: longint, Range: [-231 to 231 - 1], Default: 0

Returns the threshold as set by SetCountCallbackThreshold.

The following constants are available for this function:

For option:

  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_ROTARY_ENCODER_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletRotaryEncoder.SetDebouncePeriod(const debounce: longword)
Parameters:
  • debounce – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Sets the period with which the threshold callback

is triggered, if the thresholds

keeps being reached.

function TBrickletRotaryEncoder.GetDebouncePeriod: longword
Returns:
  • debounce – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 100

Returns the debounce period as set by SetDebouncePeriod.

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: TBrickletRotaryEncoder; const value: longint);
begin
  WriteLn(Format('Value: %d', [value]));
end;

rotaryEncoder.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 TBrickletRotaryEncoder.OnCount
procedure(sender: TBrickletRotaryEncoder; const count: longint) of object;
Callback Parameters:
  • sender – Type: TBrickletRotaryEncoder
  • count – Type: longint, Range: [-231 to 231 - 1]

This callback is triggered periodically with the period that is set by SetCountCallbackPeriod. The parameter is the count of the encoder.

The OnCount callback is only triggered if the count has changed since the last triggering.

property TBrickletRotaryEncoder.OnCountReached
procedure(sender: TBrickletRotaryEncoder; const count: longint) of object;
Callback Parameters:
  • sender – Type: TBrickletRotaryEncoder
  • count – Type: longint, Range: [-231 to 231 - 1]

This callback is triggered when the threshold as set by SetCountCallbackThreshold is reached. The parameter is the count of the encoder.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by SetDebouncePeriod.

property TBrickletRotaryEncoder.OnPressed
procedure(sender: TBrickletRotaryEncoder) of object;
Callback Parameters:
  • sender – Type: TBrickletRotaryEncoder

This callback is triggered when the button is pressed.

property TBrickletRotaryEncoder.OnReleased
procedure(sender: TBrickletRotaryEncoder) of object;
Callback Parameters:
  • sender – Type: TBrickletRotaryEncoder

This callback is triggered when the button is released.

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 TBrickletRotaryEncoder.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 TBrickletRotaryEncoder.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:

  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_COUNT_CALLBACK_PERIOD = 2
  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_COUNT_CALLBACK_THRESHOLD = 4
  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_DEBOUNCE_PERIOD = 6
procedure TBrickletRotaryEncoder.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:

  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_COUNT_CALLBACK_PERIOD = 2
  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_COUNT_CALLBACK_THRESHOLD = 4
  • BRICKLET_ROTARY_ENCODER_FUNCTION_SET_DEBOUNCE_PERIOD = 6
procedure TBrickletRotaryEncoder.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.

Constants

const BRICKLET_ROTARY_ENCODER_DEVICE_IDENTIFIER

This constant is used to identify a Rotary Encoder Bricklet.

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 BRICKLET_ROTARY_ENCODER_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Rotary Encoder Bricklet.