Delphi/Lazarus - Hall Effect Bricklet¶

Simple¶

Download (ExampleSimple.pas)

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program ExampleSimple;

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

uses
  SysUtils, IPConnection, BrickletHallEffect;

type
  TExample = class
  private
    ipcon: TIPConnection;
    he: TBrickletHallEffect;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

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

  { Create device object }
  he := TBrickletHallEffect.Create(UID, ipcon);

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

  { Get current edge count without reset }
  count := he.GetEdgeCount(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, BrickletHallEffect;

type
  TExample = class
  private
    ipcon: TIPConnection;
    he: TBrickletHallEffect;
  public
    procedure EdgeCountCB(sender: TBrickletHallEffect; const count: longword;
                          const value: boolean);
    procedure Execute;
  end;

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

var
  e: TExample;

{ Callback procedure for edge count callback }
procedure TExample.EdgeCountCB(sender: TBrickletHallEffect; const count: longword;
                               const value: boolean);
begin
  WriteLn(Format('Count: %d', [count]));
end;

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

  { Create device object }
  he := TBrickletHallEffect.Create(UID, ipcon);

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

  { Register edge count callback to procedure EdgeCountCB }
  he.OnEdgeCount := {$ifdef FPC}@{$endif}EdgeCountCB;

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

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

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

Basic Functions¶

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

Parameters:	uid – Type: string ipcon – Type: TIPConnection
Returns:	hallEffect – Type: TBrickletHallEffect

Creates an object with the unique device ID uid:

hallEffect := TBrickletHallEffect.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletHallEffect.GetValue: boolean¶

Returns:	value – Type: boolean

Returns true if a magnetic field of 3.5 millitesla or greater is detected.

function TBrickletHallEffect.GetEdgeCount(const resetCounter: boolean): longword¶

Parameters:	resetCounter – Type: boolean
Returns:	count – Type: longword, Range: [0 to 232 - 1]

Returns the current value of the edge counter. You can configure edge type (rising, falling, both) that is counted with SetEdgeCountConfig.

If you set the reset counter to true, the count is set back to 0 directly after it is read.

Advanced Functions¶

procedure TBrickletHallEffect.SetEdgeCountConfig(const edgeType: byte; const debounce: byte)¶

Parameters:	edgeType – Type: byte, Range: See constants, Default: 0 debounce – Type: byte, Unit: 1 ms, Range: [0 to 255], Default: 100

The edge type parameter configures if rising edges, falling edges or both are counted. Possible edge types are:

• 0 = rising
• 1 = falling
• 2 = both

A magnetic field of 3.5 millitesla or greater causes a falling edge and a magnetic field of 2.5 millitesla or smaller causes a rising edge.

If a magnet comes near the Bricklet the signal goes low (falling edge), if a magnet is removed from the vicinity the signal goes high (rising edge).

Configuring an edge counter resets its value to 0.

If you don't know what any of this means, just leave it at default. The default configuration is very likely OK for you.

The following constants are available for this function:

For edgeType:

• BRICKLET_HALL_EFFECT_EDGE_TYPE_RISING = 0
• BRICKLET_HALL_EFFECT_EDGE_TYPE_FALLING = 1
• BRICKLET_HALL_EFFECT_EDGE_TYPE_BOTH = 2

procedure TBrickletHallEffect.GetEdgeCountConfig(out edgeType: byte; out debounce: byte)¶

Output Parameters:	edgeType – Type: byte, Range: See constants, Default: 0 debounce – Type: byte, Unit: 1 ms, Range: [0 to 255], Default: 100

Returns the edge type and debounce time as set by SetEdgeCountConfig.

The following constants are available for this function:

For edgeType:

• BRICKLET_HALL_EFFECT_EDGE_TYPE_RISING = 0
• BRICKLET_HALL_EFFECT_EDGE_TYPE_FALLING = 1
• BRICKLET_HALL_EFFECT_EDGE_TYPE_BOTH = 2

procedure TBrickletHallEffect.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 at 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 TBrickletHallEffect.SetEdgeInterrupt(const edges: longword)¶

Parameters:	edges – Type: longword, Range: [0 to 232 - 1], Default: 0

Sets the number of edges until an interrupt is invoked.

If edges is set to n, an interrupt is invoked for every n-th detected edge.

If edges is set to 0, the interrupt is disabled.

function TBrickletHallEffect.GetEdgeInterrupt: longword¶

Returns:	edges – Type: longword, Range: [0 to 232 - 1], Default: 0

Returns the edges as set by SetEdgeInterrupt.

procedure TBrickletHallEffect.SetEdgeCountCallbackPeriod(const period: longword)¶

Parameters:	period – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

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

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

function TBrickletHallEffect.GetEdgeCountCallbackPeriod: longword¶

Returns:	period – Type: longword, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0

Returns the period as set by SetEdgeCountCallbackPeriod.

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

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

The available callback properties and their parameter types are described below.

property TBrickletHallEffect.OnEdgeCount¶

procedure(sender: TBrickletHallEffect; const count: longword; const value: boolean) of object;

Callback Parameters:	sender – Type: TBrickletHallEffect count – Type: longword, Range: [0 to 232 - 1] value – Type: boolean

This callback is triggered periodically with the period that is set by SetEdgeCountCallbackPeriod. The parameters are the current count and the current value (see GetValue and GetEdgeCount).

The OnEdgeCount callback is only triggered if the count or value changed since the last triggering.

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 TBrickletHallEffect.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 TBrickletHallEffect.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_HALL_EFFECT_FUNCTION_SET_EDGE_COUNT_CONFIG = 3
• BRICKLET_HALL_EFFECT_FUNCTION_SET_EDGE_INTERRUPT = 5
• BRICKLET_HALL_EFFECT_FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7

procedure TBrickletHallEffect.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_HALL_EFFECT_FUNCTION_SET_EDGE_COUNT_CONFIG = 3
• BRICKLET_HALL_EFFECT_FUNCTION_SET_EDGE_INTERRUPT = 5
• BRICKLET_HALL_EFFECT_FUNCTION_SET_EDGE_COUNT_CALLBACK_PERIOD = 7

procedure TBrickletHallEffect.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_HALL_EFFECT_DEVICE_IDENTIFIER¶

This constant is used to identify a Hall Effect 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_HALL_EFFECT_DEVICE_DISPLAY_NAME¶

This constant represents the human readable name of a Hall Effect Bricklet.