This is the description of the Delphi/Lazarus API bindings for the Barometer Bricklet. General information and technical specifications for the Barometer Bricklet are summarized in its hardware description.
An installation guide for the Delphi/Lazarus API bindings is part of their general description.
The example code below is Public Domain (CC0 1.0).
1program ExampleSimple;
2
3{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
4{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}
5
6uses
7 SysUtils, IPConnection, BrickletBarometer;
8
9type
10 TExample = class
11 private
12 ipcon: TIPConnection;
13 b: TBrickletBarometer;
14 public
15 procedure Execute;
16 end;
17
18const
19 HOST = 'localhost';
20 PORT = 4223;
21 UID = 'XYZ'; { Change XYZ to the UID of your Barometer Bricklet }
22
23var
24 e: TExample;
25
26procedure TExample.Execute;
27var airPressure, altitude: longint;
28begin
29 { Create IP connection }
30 ipcon := TIPConnection.Create;
31
32 { Create device object }
33 b := TBrickletBarometer.Create(UID, ipcon);
34
35 { Connect to brickd }
36 ipcon.Connect(HOST, PORT);
37 { Don't use device before ipcon is connected }
38
39 { Get current air pressure }
40 airPressure := b.GetAirPressure;
41 WriteLn(Format('Air Pressure: %f hPa', [airPressure/1000.0]));
42
43 { Get current altitude }
44 altitude := b.GetAltitude;
45 WriteLn(Format('Altitude: %f m', [altitude/100.0]));
46
47 WriteLn('Press key to exit');
48 ReadLn;
49 ipcon.Destroy; { Calls ipcon.Disconnect internally }
50end;
51
52begin
53 e := TExample.Create;
54 e.Execute;
55 e.Destroy;
56end.
Download (ExampleCallback.pas)
1program ExampleCallback;
2
3{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
4{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}
5
6uses
7 SysUtils, IPConnection, BrickletBarometer;
8
9type
10 TExample = class
11 private
12 ipcon: TIPConnection;
13 b: TBrickletBarometer;
14 public
15 procedure AirPressureCB(sender: TBrickletBarometer; const airPressure: longint);
16 procedure Execute;
17 end;
18
19const
20 HOST = 'localhost';
21 PORT = 4223;
22 UID = 'XYZ'; { Change XYZ to the UID of your Barometer Bricklet }
23
24var
25 e: TExample;
26
27{ Callback procedure for air pressure callback }
28procedure TExample.AirPressureCB(sender: TBrickletBarometer; const airPressure: longint);
29begin
30 WriteLn(Format('Air Pressure: %f hPa', [airPressure/1000.0]));
31end;
32
33procedure TExample.Execute;
34begin
35 { Create IP connection }
36 ipcon := TIPConnection.Create;
37
38 { Create device object }
39 b := TBrickletBarometer.Create(UID, ipcon);
40
41 { Connect to brickd }
42 ipcon.Connect(HOST, PORT);
43 { Don't use device before ipcon is connected }
44
45 { Register air pressure callback to procedure AirPressureCB }
46 b.OnAirPressure := {$ifdef FPC}@{$endif}AirPressureCB;
47
48 { Set period for air pressure callback to 1s (1000ms)
49 Note: The air pressure callback is only called every second
50 if the air pressure has changed since the last call! }
51 b.SetAirPressureCallbackPeriod(1000);
52
53 WriteLn('Press key to exit');
54 ReadLn;
55 ipcon.Destroy; { Calls ipcon.Disconnect internally }
56end;
57
58begin
59 e := TExample.Create;
60 e.Execute;
61 e.Destroy;
62end.
Download (ExampleThreshold.pas)
1program ExampleThreshold;
2
3{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
4{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}
5
6uses
7 SysUtils, IPConnection, BrickletBarometer;
8
9type
10 TExample = class
11 private
12 ipcon: TIPConnection;
13 b: TBrickletBarometer;
14 public
15 procedure AirPressureReachedCB(sender: TBrickletBarometer;
16 const airPressure: longint);
17 procedure Execute;
18 end;
19
20const
21 HOST = 'localhost';
22 PORT = 4223;
23 UID = 'XYZ'; { Change XYZ to the UID of your Barometer Bricklet }
24
25var
26 e: TExample;
27
28{ Callback procedure for air pressure reached callback }
29procedure TExample.AirPressureReachedCB(sender: TBrickletBarometer;
30 const airPressure: longint);
31begin
32 WriteLn(Format('Air Pressure: %f hPa', [airPressure/1000.0]));
33 WriteLn('Enjoy the potentially good weather!');
34end;
35
36procedure TExample.Execute;
37begin
38 { Create IP connection }
39 ipcon := TIPConnection.Create;
40
41 { Create device object }
42 b := TBrickletBarometer.Create(UID, ipcon);
43
44 { Connect to brickd }
45 ipcon.Connect(HOST, PORT);
46 { Don't use device before ipcon is connected }
47
48 { Get threshold callbacks with a debounce time of 10 seconds (10000ms) }
49 b.SetDebouncePeriod(10000);
50
51 { Register air pressure reached callback to procedure AirPressureReachedCB }
52 b.OnAirPressureReached := {$ifdef FPC}@{$endif}AirPressureReachedCB;
53
54 { Configure threshold for air pressure "greater than 1025 hPa" }
55 b.SetAirPressureCallbackThreshold('>', 1025*1000, 0);
56
57 WriteLn('Press key to exit');
58 ReadLn;
59 ipcon.Destroy; { Calls ipcon.Disconnect internally }
60end;
61
62begin
63 e := TExample.Create;
64 e.Execute;
65 e.Destroy;
66end.
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.
| Parameters: |
|
|---|---|
| Returns: |
|
Creates an object with the unique device ID uid:
barometer := TBrickletBarometer.Create('YOUR_DEVICE_UID', ipcon);
This object can then be used after the IP Connection is connected.
| Returns: |
|
|---|
Returns the air pressure of the air pressure sensor.
If you want to get the air pressure periodically, it is recommended to use the
OnAirPressure callback and set the period with
SetAirPressureCallbackPeriod.
| Returns: |
|
|---|
Returns the relative altitude of the air pressure sensor. The value is
calculated based on the difference between the current air pressure
and the reference air pressure that can be set with SetReferenceAirPressure.
If you want to get the altitude periodically, it is recommended to use the
OnAltitude callback and set the period with
SetAltitudeCallbackPeriod.
| Parameters: |
|
|---|
Sets the reference air pressure for the altitude calculation. Setting the reference to the current air pressure results in a calculated altitude of 0cm. Passing 0 is a shortcut for passing the current air pressure as reference.
Well known reference values are the Q codes QNH and QFE used in aviation.
| Returns: |
|
|---|
Returns the reference air pressure as set by SetReferenceAirPressure.
| Returns: |
|
|---|
Returns the temperature of the air pressure sensor.
This temperature is used internally for temperature compensation of the air pressure measurement. It is not as accurate as the temperature measured by the Temperature Bricklet or the Temperature IR Bricklet.
| Parameters: |
|
|---|
Sets the different averaging parameters. It is possible to set the length of a normal averaging for the temperature and pressure, as well as an additional length of a moving average for the pressure. The moving average is calculated from the normal averages. There is no moving average for the temperature.
Setting the all three parameters to 0 will turn the averaging completely off. If the averaging is off, there is lots of noise on the data, but the data is without delay. Thus we recommend to turn the averaging off if the Barometer Bricklet data is to be used for sensor fusion with other sensors.
Added in version 2.0.1$nbsp;(Plugin).
| Output Parameters: |
|
|---|
Returns the averaging configuration as set by SetAveraging.
Added in version 2.0.1$nbsp;(Plugin).
| Parameters: |
|
|---|
Sets the I2C mode. Possible modes are:
0: Fast (400kHz)
1: Slow (100kHz)
If you have problems with obvious outliers in the Barometer Bricklet measurements, they may be caused by EMI issues. In this case it may be helpful to lower the I2C speed.
It is however not recommended to lower the I2C speed in applications where a high throughput needs to be achieved.
The following constants are available for this function:
For mode:
BRICKLET_BAROMETER_I2C_MODE_FAST = 0
BRICKLET_BAROMETER_I2C_MODE_SLOW = 1
Added in version 2.0.3$nbsp;(Plugin).
| Returns: |
|
|---|
Returns the I2C mode as set by SetI2CMode.
The following constants are available for this function:
For mode:
BRICKLET_BAROMETER_I2C_MODE_FAST = 0
BRICKLET_BAROMETER_I2C_MODE_SLOW = 1
Added in version 2.0.3$nbsp;(Plugin).
| Output Parameters: |
|
|---|
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.
| Parameters: |
|
|---|
Sets the period with which the OnAirPressure callback is triggered
periodically. A value of 0 turns the callback off.
The OnAirPressure callback is only triggered if the air pressure has
changed since the last triggering.
| Returns: |
|
|---|
Returns the period as set by SetAirPressureCallbackPeriod.
| Parameters: |
|
|---|
Sets the period with which the OnAltitude callback is triggered
periodically. A value of 0 turns the callback off.
The OnAltitude callback is only triggered if the altitude has changed since
the last triggering.
| Returns: |
|
|---|
Returns the period as set by SetAltitudeCallbackPeriod.
| Parameters: |
|
|---|
Sets the thresholds for the OnAirPressureReached callback.
The following options are possible:
Option |
Description |
|---|---|
'x' |
Callback is turned off |
'o' |
Callback is triggered when the air pressure is outside the min and max values |
'i' |
Callback is triggered when the air pressure is inside the min and max values |
'<' |
Callback is triggered when the air pressure is smaller than the min value (max is ignored) |
'>' |
Callback is triggered when the air pressure is greater than the min value (max is ignored) |
The following constants are available for this function:
For option:
BRICKLET_BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BRICKLET_BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BRICKLET_BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BRICKLET_BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BRICKLET_BAROMETER_THRESHOLD_OPTION_GREATER = '>'
| Output Parameters: |
|
|---|
Returns the threshold as set by SetAirPressureCallbackThreshold.
The following constants are available for this function:
For option:
BRICKLET_BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BRICKLET_BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BRICKLET_BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BRICKLET_BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BRICKLET_BAROMETER_THRESHOLD_OPTION_GREATER = '>'
| Parameters: |
|
|---|
Sets the thresholds for the OnAltitudeReached callback.
The following options are possible:
Option |
Description |
|---|---|
'x' |
Callback is turned off |
'o' |
Callback is triggered when the altitude is outside the min and max values |
'i' |
Callback is triggered when the altitude is inside the min and max values |
'<' |
Callback is triggered when the altitude is smaller than the min value (max is ignored) |
'>' |
Callback is triggered when the altitude is greater than the min value (max is ignored) |
The following constants are available for this function:
For option:
BRICKLET_BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BRICKLET_BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BRICKLET_BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BRICKLET_BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BRICKLET_BAROMETER_THRESHOLD_OPTION_GREATER = '>'
| Output Parameters: |
|
|---|
Returns the threshold as set by SetAltitudeCallbackThreshold.
The following constants are available for this function:
For option:
BRICKLET_BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BRICKLET_BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BRICKLET_BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BRICKLET_BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BRICKLET_BAROMETER_THRESHOLD_OPTION_GREATER = '>'
| Parameters: |
|
|---|
Sets the period with which the threshold callbacks
are triggered, if the thresholds
keep being reached.
| Returns: |
|
|---|
Returns the debounce period as set by SetDebouncePeriod.
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: TBrickletBarometer; const value: longint); begin WriteLn(Format('Value: %d', [value])); end; barometer.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;
The available callback properties and their parameter types 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.
procedure(sender: TBrickletBarometer; const airPressure: longint) of object;
| Callback Parameters: |
|
|---|
This callback is triggered periodically with the period that is set by
SetAirPressureCallbackPeriod. The parameter is the air
pressure of the air pressure sensor.
The OnAirPressure callback is only triggered if the air pressure has
changed since the last triggering.
procedure(sender: TBrickletBarometer; const altitude: longint) of object;
| Callback Parameters: |
|
|---|
This callback is triggered periodically with the period that is set by
SetAltitudeCallbackPeriod. The parameter is the altitude of
the air pressure sensor.
The OnAltitude callback is only triggered if the altitude has changed since
the last triggering.
procedure(sender: TBrickletBarometer; const airPressure: longint) of object;
| Callback Parameters: |
|
|---|
This callback is triggered when the threshold as set by
SetAirPressureCallbackThreshold is reached.
The parameter is the air pressure of the air pressure sensor.
If the threshold keeps being reached, the callback is triggered periodically
with the period as set by SetDebouncePeriod.
procedure(sender: TBrickletBarometer; const altitude: longint) of object;
| Callback Parameters: |
|
|---|
This callback is triggered when the threshold as set by
SetAltitudeCallbackThreshold is reached.
The parameter is the altitude of the air pressure sensor.
If the threshold keeps being reached, the callback is triggered periodically
with the period as set by SetDebouncePeriod.
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.
| Output Parameters: |
|
|---|
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.
| Parameters: |
|
|---|---|
| Returns: |
|
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_BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
BRICKLET_BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
BRICKLET_BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
BRICKLET_BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
BRICKLET_BAROMETER_FUNCTION_SET_DEBOUNCE_PERIOD = 11
BRICKLET_BAROMETER_FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
BRICKLET_BAROMETER_FUNCTION_SET_AVERAGING = 20
BRICKLET_BAROMETER_FUNCTION_SET_I2C_MODE = 22
| Parameters: |
|
|---|
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_BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
BRICKLET_BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
BRICKLET_BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
BRICKLET_BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
BRICKLET_BAROMETER_FUNCTION_SET_DEBOUNCE_PERIOD = 11
BRICKLET_BAROMETER_FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
BRICKLET_BAROMETER_FUNCTION_SET_AVERAGING = 20
BRICKLET_BAROMETER_FUNCTION_SET_I2C_MODE = 22
| Parameters: |
|
|---|
Changes the response expected flag for all setter and callback configuration functions of this device at once.
This constant is used to identify a Barometer 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.
This constant represents the human readable name of a Barometer Bricklet.