Delphi/Lazarus - Air Quality Bricklet

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

type
  TExample = class
  private
    ipcon: TIPConnection;
    aq: TBrickletAirQuality;
  public
    procedure Execute;
  end;

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

var
  e: TExample;

procedure TExample.Execute;
var iaqIndex, temperature, humidity, airPressure: longint; iaqIndexAccuracy: byte;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  aq := TBrickletAirQuality.Create(UID, ipcon);

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

  { Get current all values }
  aq.GetAllValues(iaqIndex, iaqIndexAccuracy, temperature, humidity, airPressure);

  WriteLn(Format('IAQ Index: %d', [iaqIndex]));

  if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE) then begin
    WriteLn('IAQ Index Accuracy: Unreliable');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_LOW) then begin
    WriteLn('IAQ Index Accuracy: Low');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM) then begin
    WriteLn('IAQ Index Accuracy: Medium');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_HIGH) then begin
    WriteLn('IAQ Index Accuracy: High');
  end;

  WriteLn(Format('Temperature: %f °C', [temperature/100.0]));
  WriteLn(Format('Humidity: %f %%RH', [humidity/100.0]));
  WriteLn(Format('Air Pressure: %f mbar', [airPressure/100.0]));

  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)

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program ExampleCallback;

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

uses
  SysUtils, IPConnection, BrickletAirQuality;

type
  TExample = class
  private
    ipcon: TIPConnection;
    aq: TBrickletAirQuality;
  public
    procedure AllValuesCB(sender: TBrickletAirQuality; const iaqIndex: longint;
                          const iaqIndexAccuracy: byte; const temperature: longint;
                          const humidity: longint; const airPressure: longint);
    procedure Execute;
  end;

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

var
  e: TExample;

{ Callback procedure for all values callback }
procedure TExample.AllValuesCB(sender: TBrickletAirQuality; const iaqIndex: longint;
                               const iaqIndexAccuracy: byte; const temperature: longint;
                               const humidity: longint; const airPressure: longint);
begin
  WriteLn(Format('IAQ Index: %d', [iaqIndex]));

  if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE) then begin
    WriteLn('IAQ Index Accuracy: Unreliable');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_LOW) then begin
    WriteLn('IAQ Index Accuracy: Low');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM) then begin
    WriteLn('IAQ Index Accuracy: Medium');
  end
  else if (iaqIndexAccuracy = BRICKLET_AIR_QUALITY_ACCURACY_HIGH) then begin
    WriteLn('IAQ Index Accuracy: High');
  end;

  WriteLn(Format('Temperature: %f °C', [temperature/100.0]));
  WriteLn(Format('Humidity: %f %%RH', [humidity/100.0]));
  WriteLn(Format('Air Pressure: %f mbar', [airPressure/100.0]));
  WriteLn('');
end;

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

  { Create device object }
  aq := TBrickletAirQuality.Create(UID, ipcon);

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

  { Register all values callback to procedure AllValuesCB }
  aq.OnAllValues := {$ifdef FPC}@{$endif}AllValuesCB;

  { Set period for all values callback to 1s (1000ms) }
  aq.SetAllValuesCallbackConfiguration(1000, 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 TBrickletAirQuality.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

airQuality := TBrickletAirQuality.Create('YOUR_DEVICE_UID', ipcon);

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

procedure TBrickletAirQuality.GetAllValues(out iaqIndex: longint; out iaqIndexAccuracy: byte; out temperature: longint; out humidity: longint; out airPressure: longint)

Returns all values measured by the Air Quality Bricklet. The values are IAQ (Indoor Air Quality) Index, IAQ Index Accuracy, Temperature, Humidity and Air Pressure.

Air Quality Index description

The values have these ranges and units:

  • IAQ Index: 0 to 500, higher value means greater level of air pollution
  • IAQ Index Accuracy: 0 = unreliable to 3 = high
  • Temperature: in steps of 0.01 °C
  • Humidity: in steps of 0.01 %RH
  • Air Pressure: in steps of 0.01 mbar

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE = 0
  • BRICKLET_AIR_QUALITY_ACCURACY_LOW = 1
  • BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM = 2
  • BRICKLET_AIR_QUALITY_ACCURACY_HIGH = 3
procedure TBrickletAirQuality.SetTemperatureOffset(const offset: longint)

Sets a temperature offset in 1/100°C. A offset of 10 will decrease the measured temperature by 0.1°C.

If you install this Bricklet into an enclosure and you want to measure the ambient temperature, you may have to decrease the measured temperature by some value to compensate for the error because of the heating inside of the enclosure.

We recommend that you leave the parts in the enclosure running for at least 24 hours such that a temperature equilibrium can be reached. After that you can measure the temperature directly outside of enclosure and set the difference as offset.

This temperature offset is used to calculate the relative humidity and IAQ index measurements. In case the Bricklet is installed in an enclosure, we recommend to measure and set the temperature offset to imporve the accuracy of the measurements.

function TBrickletAirQuality.GetTemperatureOffset: longint

Returns the temperature offset as set by SetTemperatureOffset.

procedure TBrickletAirQuality.GetIAQIndex(out iaqIndex: longint; out iaqIndexAccuracy: byte)

Returns the IAQ index and accuracy. The IAQ index goes from 0 to 500. The higher the IAQ index, the greater the level of air pollution.

IAQ index description

If you want to get the value periodically, it is recommended to use the OnIAQIndex callback. You can set the callback configuration with SetIAQIndexCallbackConfiguration.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE = 0
  • BRICKLET_AIR_QUALITY_ACCURACY_LOW = 1
  • BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM = 2
  • BRICKLET_AIR_QUALITY_ACCURACY_HIGH = 3
function TBrickletAirQuality.GetTemperature: longint

Returns temperature in steps of 0.01 °C.

If you want to get the value periodically, it is recommended to use the OnTemperature callback. You can set the callback configuration with SetTemperatureCallbackConfiguration.

function TBrickletAirQuality.GetHumidity: longint

Returns relative humidity in steps of 0.01 %RH.

If you want to get the value periodically, it is recommended to use the OnHumidity callback. You can set the callback configuration with SetHumidityCallbackConfiguration.

function TBrickletAirQuality.GetAirPressure: longint

Returns air pressure in steps of 0.01 mbar.

If you want to get the value periodically, it is recommended to use the OnAirPressure callback. You can set the callback configuration with SetAirPressureCallbackConfiguration.

Advanced Functions

function TBrickletAirQuality.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 TBrickletAirQuality.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 TBrickletAirQuality.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_AIR_QUALITY_FUNCTION_SET_TEMPERATURE_OFFSET = 2
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_ALL_VALUES_CALLBACK_CONFIGURATION = 4
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_IAQ_INDEX_CALLBACK_CONFIGURATION = 8
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_TEMPERATURE_CALLBACK_CONFIGURATION = 12
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_HUMIDITY_CALLBACK_CONFIGURATION = 16
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_AIR_PRESSURE_CALLBACK_CONFIGURATION = 20
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BRICKLET_AIR_QUALITY_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BRICKLET_AIR_QUALITY_FUNCTION_RESET = 243
  • BRICKLET_AIR_QUALITY_FUNCTION_WRITE_UID = 248
procedure TBrickletAirQuality.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletAirQuality.GetSPITFPErrorCount(out errorCountAckChecksum: longword; out errorCountMessageChecksum: longword; out errorCountFrame: longword; out errorCountOverflow: longword)

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

function TBrickletAirQuality.SetBootloaderMode(const mode: byte): byte

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_OK = 0
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_INVALID_MODE = 1
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_NO_CHANGE = 2
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BRICKLET_AIR_QUALITY_BOOTLOADER_STATUS_CRC_MISMATCH = 5
function TBrickletAirQuality.GetBootloaderMode: byte

Returns the current bootloader mode, see SetBootloaderMode.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICKLET_AIR_QUALITY_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
procedure TBrickletAirQuality.SetWriteFirmwarePointer(const pointer: longword)

Sets the firmware pointer for WriteFirmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

function TBrickletAirQuality.WriteFirmware(const data: array [0..63] of byte): byte

Writes 64 Bytes of firmware at the position as written by SetWriteFirmwarePointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

procedure TBrickletAirQuality.SetStatusLEDConfig(const config: byte)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletAirQuality.GetStatusLEDConfig: byte

Returns the configuration as set by SetStatusLEDConfig

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_OFF = 0
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_ON = 1
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICKLET_AIR_QUALITY_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickletAirQuality.GetChipTemperature: smallint

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

procedure TBrickletAirQuality.Reset

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

procedure TBrickletAirQuality.WriteUID(const uid: longword)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

function TBrickletAirQuality.ReadUID: longword

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

procedure TBrickletAirQuality.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 TBrickletAirQuality.SetAllValuesCallbackConfiguration(const period: longword; const valueHasToChange: boolean)

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

If the value has to change-parameter is set to true, the callback is only triggered after at least one of the values has changed. If the values didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

The default value is (0, false).

procedure TBrickletAirQuality.GetAllValuesCallbackConfiguration(out period: longword; out valueHasToChange: boolean)

Returns the callback configuration as set by SetAllValuesCallbackConfiguration.

procedure TBrickletAirQuality.SetIAQIndexCallbackConfiguration(const period: longword; const valueHasToChange: boolean)

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

If the value has to change-parameter is set to true, the callback is only triggered after at least one of the values has changed. If the values didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

The default value is (0, false).

procedure TBrickletAirQuality.GetIAQIndexCallbackConfiguration(out period: longword; out valueHasToChange: boolean)

Returns the callback configuration as set by SetIAQIndexCallbackConfiguration.

procedure TBrickletAirQuality.SetTemperatureCallbackConfiguration(const period: longword; const valueHasToChange: boolean; const option: char; const min: longint; const max: longint)

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the OnTemperature callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletAirQuality.GetTemperatureCallbackConfiguration(out period: longword; out valueHasToChange: boolean; out option: char; out min: longint; out max: longint)

Returns the callback configuration as set by SetTemperatureCallbackConfiguration.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletAirQuality.SetHumidityCallbackConfiguration(const period: longword; const valueHasToChange: boolean; const option: char; const min: longint; const max: longint)

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the OnHumidity callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletAirQuality.GetHumidityCallbackConfiguration(out period: longword; out valueHasToChange: boolean; out option: char; out min: longint; out max: longint)

Returns the callback configuration as set by SetHumidityCallbackConfiguration.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletAirQuality.SetAirPressureCallbackConfiguration(const period: longword; const valueHasToChange: boolean; const option: char; const min: longint; const max: longint)

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

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the OnAirPressure callback.

The following options are possible:

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

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

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

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'
procedure TBrickletAirQuality.GetAirPressureCallbackConfiguration(out period: longword; out valueHasToChange: boolean; out option: char; out min: longint; out max: longint)

Returns the callback configuration as set by SetAirPressureCallbackConfiguration.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OFF = 'x'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_INSIDE = 'i'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_SMALLER = '<'
  • BRICKLET_AIR_QUALITY_THRESHOLD_OPTION_GREATER = '>'

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

airQuality.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 TBrickletAirQuality.OnAllValues
procedure(sender: TBrickletAirQuality; const iaqIndex: longint; const iaqIndexAccuracy: byte; const temperature: longint; const humidity: longint; const airPressure: longint) of object;

This callback is triggered periodically according to the configuration set by SetAllValuesCallbackConfiguration.

The parameters are the same as GetAllValues.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE = 0
  • BRICKLET_AIR_QUALITY_ACCURACY_LOW = 1
  • BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM = 2
  • BRICKLET_AIR_QUALITY_ACCURACY_HIGH = 3
property TBrickletAirQuality.OnIAQIndex
procedure(sender: TBrickletAirQuality; const iaqIndex: longint; const iaqIndexAccuracy: byte) of object;

This callback is triggered periodically according to the configuration set by SetIAQIndexCallbackConfiguration.

The parameters are the same as GetIAQIndex.

The following constants are available for this function:

  • BRICKLET_AIR_QUALITY_ACCURACY_UNRELIABLE = 0
  • BRICKLET_AIR_QUALITY_ACCURACY_LOW = 1
  • BRICKLET_AIR_QUALITY_ACCURACY_MEDIUM = 2
  • BRICKLET_AIR_QUALITY_ACCURACY_HIGH = 3
property TBrickletAirQuality.OnTemperature
procedure(sender: TBrickletAirQuality; const temperature: longint) of object;

This callback is triggered periodically according to the configuration set by SetTemperatureCallbackConfiguration.

The parameter is the same as GetTemperature.

property TBrickletAirQuality.OnHumidity
procedure(sender: TBrickletAirQuality; const humidity: longint) of object;

This callback is triggered periodically according to the configuration set by SetHumidityCallbackConfiguration.

The parameter is the same as GetHumidity.

property TBrickletAirQuality.OnAirPressure
procedure(sender: TBrickletAirQuality; const airPressure: longint) of object;

This callback is triggered periodically according to the configuration set by SetAirPressureCallbackConfiguration.

The parameter is the same as GetAirPressure.

Constants

const BRICKLET_AIR_QUALITY_DEVICE_IDENTIFIER

This constant is used to identify a Air Quality 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_AIR_QUALITY_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Air Quality Bricklet.