Delphi/Lazarus - CO2 Bricklet – Tinkerforge

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# Delphi/Lazarus - CO2 Bricklet

Note

This Bricklet is currently in the prototype stage and the software/hardware as well as the documentation is in an incomplete state.

This is the description of the Delphi/Lazarus API bindings for the CO2 Bricklet. General information and technical specifications for the CO2 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).

## 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 `TBrickletCO2.``Create`(const uid: string; ipcon: TIPConnection)

  Creates an object with the unique device ID `uid`:

      co2 := TBrickletCO2.Create('YOUR_DEVICE_UID', ipcon);

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

function `TBrickletCO2.``GetCO2Concentration`: word

  Returns the measured CO2 concentration. The value is in ppb and between TBD and TBD.

  If you want to get the CO2 concentration periodically, it is recommended to use the callback `OnCO2Concentration` and set the period with `SetCO2ConcentrationCallbackPeriod`.

### Advanced Functions

function `TBrickletCO2.``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 `TBrickletCO2.``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 `TBrickletCO2.``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 and callbacks it is always disabled.

  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_CO2_FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_PERIOD = 2
  - BRICKLET_CO2_FUNCTION_SET_CO2_CONCENTRATION_CALLBACK_THRESHOLD = 4
  - BRICKLET_CO2_FUNCTION_SET_DEBOUNCE_PERIOD = 6

procedure `TBrickletCO2.``SetResponseExpectedAll`(const responseExpected: boolean)

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

procedure `TBrickletCO2.``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 `TBrickletCO2.``SetCO2ConcentrationCallbackPeriod`(const period: longword)

  Sets the period in ms with which the `OnCO2Concentration` callback is triggered periodically. A value of 0 turns the callback off.

  `OnCO2Concentration` is only triggered if the co2_concentration has changed since the last triggering.

  The default value is 0.

function `TBrickletCO2.``GetCO2ConcentrationCallbackPeriod`: longword

  Returns the period as set by `SetCO2ConcentrationCallbackPeriod`.

procedure `TBrickletCO2.``SetCO2ConcentrationCallbackThreshold`(const option: char; const min: smallint; const max: smallint)

  Sets the thresholds for the `OnCO2ConcentrationReached` callback.

  The following options are possible:

  Option | Description
  --- | ---
  'x' | Callback is turned off
  'o' | Callback is triggered when the co2_concentration is outside the min and max values
  'i' | Callback is triggered when the co2_concentration is inside the min and max values
  '<' | Callback is triggered when the co2_concentration is smaller than the min value (max is ignored)
  '>' | Callback is triggered when the co2_concentration 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_CO2_THRESHOLD_OPTION_OFF = 'x'
  - BRICKLET_CO2_THRESHOLD_OPTION_OUTSIDE = 'o'
  - BRICKLET_CO2_THRESHOLD_OPTION_INSIDE = 'i'
  - BRICKLET_CO2_THRESHOLD_OPTION_SMALLER = '<'
  - BRICKLET_CO2_THRESHOLD_OPTION_GREATER = '>'

procedure `TBrickletCO2.``GetCO2ConcentrationCallbackThreshold`(out option: char; out min: smallint; out max: smallint)

  Returns the threshold as set by `SetCO2ConcentrationCallbackThreshold`.

  The following constants are available for this function:

  - BRICKLET_CO2_THRESHOLD_OPTION_OFF = 'x'
  - BRICKLET_CO2_THRESHOLD_OPTION_OUTSIDE = 'o'
  - BRICKLET_CO2_THRESHOLD_OPTION_INSIDE = 'i'
  - BRICKLET_CO2_THRESHOLD_OPTION_SMALLER = '<'
  - BRICKLET_CO2_THRESHOLD_OPTION_GREATER = '>'

procedure `TBrickletCO2.``SetDebouncePeriod`(const debounce: longword)

  Sets the period in ms with which the threshold callbacks

  - `OnCO2ConcentrationReached`,

  are triggered, if the thresholds

  - `SetCO2ConcentrationCallbackThreshold`,

  keep being reached.

  The default value is 100.

function `TBrickletCO2.``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: TBrickletCO2; const param: word);
>     begin
>       WriteLn(param);
>     end;

>     co2.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 `TBrickletCO2.``OnCO2Concentration`

      procedure(sender: TBrickletCO2; const co2Concentration: word) of object;

  This callback is triggered periodically with the period that is set by `SetCO2ConcentrationCallbackPeriod`. The parameter is the co2 concentration of the sensor.

  `OnCO2Concentration` is only triggered if the co2 concentration has changed since the last triggering.

property `TBrickletCO2.``OnCO2ConcentrationReached`

      procedure(sender: TBrickletCO2; const co2Concentration: word) of object;

  This callback is triggered when the threshold as set by `SetCO2ConcentrationCallbackThreshold` is reached. The parameter is the CO2 concentration.

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

### Constants

const `BRICKLET_CO2_DEVICE_IDENTIFIER`

  This constant is used to identify a CO2 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.

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