Delphi/Lazarus - Current25 Bricklet

This is the description of the Delphi/Lazarus API bindings for the Current25 Bricklet. General information and technical specifications for the Current25 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)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
program ExampleSimple;

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

uses
  SysUtils, IPConnection, BrickletCurrent25;

type
  TExample = class
  private
    ipcon: TIPConnection;
    c: TBrickletCurrent25;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Current25 Bricklet }

var
  e: TExample;

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

  { Create device object }
  c := TBrickletCurrent25.Create(UID, ipcon);

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

  { Get current current }
  current := c.GetCurrent;
  WriteLn(Format('Current: %f A', [current/1000.0]));

  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)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
program ExampleCallback;

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

uses
  SysUtils, IPConnection, BrickletCurrent25;

type
  TExample = class
  private
    ipcon: TIPConnection;
    c: TBrickletCurrent25;
  public
    procedure CurrentCB(sender: TBrickletCurrent25; const current: smallint);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Current25 Bricklet }

var
  e: TExample;

{ Callback procedure for current callback }
procedure TExample.CurrentCB(sender: TBrickletCurrent25; const current: smallint);
begin
  WriteLn(Format('Current: %f A', [current/1000.0]));
end;

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

  { Create device object }
  c := TBrickletCurrent25.Create(UID, ipcon);

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

  { Register current callback to procedure CurrentCB }
  c.OnCurrent := {$ifdef FPC}@{$endif}CurrentCB;

  { Set period for current callback to 1s (1000ms)
    Note: The current callback is only called every second
          if the current has changed since the last call! }
  c.SetCurrentCallbackPeriod(1000);

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

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

Threshold

Download (ExampleThreshold.pas)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
program ExampleThreshold;

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

uses
  SysUtils, IPConnection, BrickletCurrent25;

type
  TExample = class
  private
    ipcon: TIPConnection;
    c: TBrickletCurrent25;
  public
    procedure CurrentReachedCB(sender: TBrickletCurrent25; const current: smallint);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your Current25 Bricklet }

var
  e: TExample;

{ Callback procedure for current reached callback }
procedure TExample.CurrentReachedCB(sender: TBrickletCurrent25; const current: smallint);
begin
  WriteLn(Format('Current: %f A', [current/1000.0]));
end;

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

  { Create device object }
  c := TBrickletCurrent25.Create(UID, ipcon);

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

  { Get threshold callbacks with a debounce time of 10 seconds (10000ms) }
  c.SetDebouncePeriod(10000);

  { Register current reached callback to procedure CurrentReachedCB }
  c.OnCurrentReached := {$ifdef FPC}@{$endif}CurrentReachedCB;

  { Configure threshold for current "greater than 5 A" }
  c.SetCurrentCallbackThreshold('>', 5*1000, 0);

  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 TBrickletCurrent25.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

current25 := TBrickletCurrent25.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletCurrent25.GetCurrent: smallint

Returns the current of the sensor. The value is in mA and between -25000mA and 25000mA.

If you want to get the current periodically, it is recommended to use the OnCurrent callback and set the period with SetCurrentCallbackPeriod.

Advanced Functions

procedure TBrickletCurrent25.Calibrate

Calibrates the 0 value of the sensor. You have to call this function when there is no current present.

The zero point of the current sensor is depending on the exact properties of the analog-to-digital converter, the length of the Bricklet cable and the temperature. Thus, if you change the Brick or the environment in which the Bricklet is used, you might have to recalibrate.

The resulting calibration will be saved on the EEPROM of the Current Bricklet.

function TBrickletCurrent25.IsOverCurrent: boolean

Returns true if more than 25A were measured.

Note

To reset this value you have to power cycle the Bricklet.

function TBrickletCurrent25.GetAnalogValue: word

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by GetCurrent is averaged over several samples to yield less noise, while GetAnalogValue gives back raw unfiltered analog values. The only reason to use GetAnalogValue is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the OnAnalogValue callback and set the period with SetAnalogValueCallbackPeriod.

function TBrickletCurrent25.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 TBrickletCurrent25.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 TBrickletCurrent25.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_CURRENT25_FUNCTION_CALIBRATE = 2
  • BRICKLET_CURRENT25_FUNCTION_SET_CURRENT_CALLBACK_PERIOD = 5
  • BRICKLET_CURRENT25_FUNCTION_SET_ANALOG_VALUE_CALLBACK_PERIOD = 7
  • BRICKLET_CURRENT25_FUNCTION_SET_CURRENT_CALLBACK_THRESHOLD = 9
  • BRICKLET_CURRENT25_FUNCTION_SET_ANALOG_VALUE_CALLBACK_THRESHOLD = 11
  • BRICKLET_CURRENT25_FUNCTION_SET_DEBOUNCE_PERIOD = 13
procedure TBrickletCurrent25.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletCurrent25.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 TBrickletCurrent25.SetCurrentCallbackPeriod(const period: longword)

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

The OnCurrent callback is only triggered if the current has changed since the last triggering.

The default value is 0.

function TBrickletCurrent25.GetCurrentCallbackPeriod: longword

Returns the period as set by SetCurrentCallbackPeriod.

procedure TBrickletCurrent25.SetAnalogValueCallbackPeriod(const period: longword)

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

The OnAnalogValue callback is only triggered if the analog value has changed since the last triggering.

The default value is 0.

function TBrickletCurrent25.GetAnalogValueCallbackPeriod: longword

Returns the period as set by SetAnalogValueCallbackPeriod.

procedure TBrickletCurrent25.SetCurrentCallbackThreshold(const option: char; const min: smallint; const max: smallint)

Sets the thresholds for the OnCurrentReached callback.

The following options are possible:

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

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

The following constants are available for this function:

  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletCurrent25.GetCurrentCallbackThreshold(out option: char; out min: smallint; out max: smallint)

Returns the threshold as set by SetCurrentCallbackThreshold.

The following constants are available for this function:

  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletCurrent25.SetAnalogValueCallbackThreshold(const option: char; const min: word; const max: word)

Sets the thresholds for the OnAnalogValueReached callback.

The following options are possible:

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

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

The following constants are available for this function:

  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletCurrent25.GetAnalogValueCallbackThreshold(out option: char; out min: word; out max: word)

Returns the threshold as set by SetAnalogValueCallbackThreshold.

The following constants are available for this function:

  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_CURRENT25_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletCurrent25.SetDebouncePeriod(const debounce: longword)

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

function TBrickletCurrent25.GetDebouncePeriod: longword

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: TBrickletCurrent25; const param: word);
begin
  WriteLn(param);
end;

current25.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 TBrickletCurrent25.OnCurrent
procedure(sender: TBrickletCurrent25; const current: smallint) of object;

This callback is triggered periodically with the period that is set by SetCurrentCallbackPeriod. The parameter is the current of the sensor.

The OnCurrent callback is only triggered if the current has changed since the last triggering.

property TBrickletCurrent25.OnAnalogValue
procedure(sender: TBrickletCurrent25; const value: word) of object;

This callback is triggered periodically with the period that is set by SetAnalogValueCallbackPeriod. The parameter is the analog value of the sensor.

The OnAnalogValue callback is only triggered if the current has changed since the last triggering.

property TBrickletCurrent25.OnCurrentReached
procedure(sender: TBrickletCurrent25; const current: smallint) of object;

This callback is triggered when the threshold as set by SetCurrentCallbackThreshold is reached. The parameter is the current of the sensor.

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

property TBrickletCurrent25.OnAnalogValueReached
procedure(sender: TBrickletCurrent25; const value: word) of object;

This callback is triggered when the threshold as set by SetAnalogValueCallbackThreshold is reached. The parameter is the analog value of the sensor.

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

property TBrickletCurrent25.OnOverCurrent
procedure(sender: TBrickletCurrent25) of object;

This callback is triggered when an over current is measured (see IsOverCurrent).

Constants

const BRICKLET_CURRENT25_DEVICE_IDENTIFIER

This constant is used to identify a Current25 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_CURRENT25_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Current25 Bricklet.