Delphi/Lazarus - Segment Display 4x7 Bricklet

This is the description of the Delphi/Lazarus API bindings for the Segment Display 4x7 Bricklet. General information and technical specifications for the Segment Display 4x7 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, BrickletSegmentDisplay4x7;

type
  TExample = class
  private
    ipcon: TIPConnection;
    sd: TBrickletSegmentDisplay4x7;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Segment Display 4x7 Bricklet }
  DIGITS : array [0..15] of byte = ($3f,$06,$5b,$4f,
                                    $66,$6d,$7d,$07,
                                    $7f,$6f,$77,$7c,
                                    $39,$5e,$79,$71);

var
  e: TExample;

procedure TExample.Execute;
var segments: array [0..3] of byte;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  sd := TBrickletSegmentDisplay4x7.Create(UID, ipcon);

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

  { Write "4223" to the display with full brightness without colon }
  segments[0] := DIGITS[4];
  segments[1] := DIGITS[2];
  segments[2] := DIGITS[2];
  segments[3] := DIGITS[3];
  sd.SetSegments(segments, 7, 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 TBrickletSegmentDisplay4x7.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

segmentDisplay4x7 := TBrickletSegmentDisplay4x7.Create('YOUR_DEVICE_UID', ipcon);

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

procedure TBrickletSegmentDisplay4x7.SetSegments(const segments: array [0..3] of byte; const brightness: byte; const colon: boolean)

The 7-segment display can be set with bitmaps. Every bit controls one segment:

Bit order of one segment

For example to set a "5" you would want to activate segments 0, 2, 3, 5 and 6. This is represented by the number 0b01101101 = 0x6d = 109.

The brightness can be set between 0 (dark) and 7 (bright). The colon parameter turns the colon of the display on or off.

procedure TBrickletSegmentDisplay4x7.GetSegments(out segments: array [0..3] of byte; out brightness: byte; out colon: boolean)

Returns the segment, brightness and color data as set by SetSegments.

Advanced Functions

procedure TBrickletSegmentDisplay4x7.StartCounter(const valueFrom: smallint; const valueTo: smallint; const increment: smallint; const length: longword)

Starts a counter with the from value that counts to the to value with the each step incremented by increment. The length of the increment is given in ms.

Example: If you set from to 0, to to 100, increment to 1 and length to 1000, a counter that goes from 0 to 100 with one second pause between each increment will be started.

The maximum values for from, to and increment is 9999, the minimum value is -999.

Using a negative increment allows to count backwards.

You can stop the counter at every time by calling SetSegments.

function TBrickletSegmentDisplay4x7.GetCounterValue: word

Returns the counter value that is currently shown on the display.

If there is no counter running a 0 will be returned.

function TBrickletSegmentDisplay4x7.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 TBrickletSegmentDisplay4x7.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 TBrickletSegmentDisplay4x7.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_SEGMENT_DISPLAY_4X7_FUNCTION_SET_SEGMENTS = 1
  • BRICKLET_SEGMENT_DISPLAY_4X7_FUNCTION_START_COUNTER = 3
procedure TBrickletSegmentDisplay4x7.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletSegmentDisplay4x7.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

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: TBrickletSegmentDisplay4x7; const param: word);
begin
  WriteLn(param);
end;

segmentDisplay4x7.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 TBrickletSegmentDisplay4x7.OnCounterFinished
procedure(sender: TBrickletSegmentDisplay4x7) of object;

This callback is triggered when the counter (see StartCounter) is finished.

Constants

const BRICKLET_SEGMENT_DISPLAY_4X7_DEVICE_IDENTIFIER

This constant is used to identify a Segment Display 4x7 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_SEGMENT_DISPLAY_4X7_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Segment Display 4x7 Bricklet.