Software / API Bindings / C/C++ / API Reference and Examples / Bricklets / Barometer Bricklet

C/C++ - Barometer Bricklet¶

This is the description of the C/C++ 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 C/C++ API bindings is part of their general description.

Examples¶

The example code below is Public Domain (CC0 1.0).

Callback¶

Download (example_callback.c)

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet

// Callback function for air pressure callback
void cb_air_pressure(int32_t air_pressure, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Air Pressure: %f hPa\n", air_pressure/1000.0);
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    Barometer b;
    barometer_create(&b, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Register air pressure callback to function cb_air_pressure
    barometer_register_callback(&b,
                                BAROMETER_CALLBACK_AIR_PRESSURE,
                                (void (*)(void))cb_air_pressure,
                                NULL);

    // Set period for air pressure callback to 1s (1000ms)
    // Note: The air pressure callback is only called every second
    //       if the air pressure has changed since the last call!
    barometer_set_air_pressure_callback_period(&b, 1000);

    printf("Press key to exit\n");
    getchar();
    barometer_destroy(&b);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Simple¶

Download (example_simple.c)

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    Barometer b;
    barometer_create(&b, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Get current air pressure
    int32_t air_pressure;
    if(barometer_get_air_pressure(&b, &air_pressure) < 0) {
        fprintf(stderr, "Could not get air pressure, probably timeout\n");
        return 1;
    }

    printf("Air Pressure: %f hPa\n", air_pressure/1000.0);

    // Get current altitude
    int32_t altitude;
    if(barometer_get_altitude(&b, &altitude) < 0) {
        fprintf(stderr, "Could not get altitude, probably timeout\n");
        return 1;
    }

    printf("Altitude: %f m\n", altitude/100.0);

    printf("Press key to exit\n");
    getchar();
    barometer_destroy(&b);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Threshold¶

Download (example_threshold.c)

#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet

// Callback function for air pressure reached callback
void cb_air_pressure_reached(int32_t air_pressure, void *user_data) {
    (void)user_data; // avoid unused parameter warning

    printf("Air Pressure: %f hPa\n", air_pressure/1000.0);
    printf("Enjoy the potentially good weather!\n");
}

int main(void) {
    // Create IP connection
    IPConnection ipcon;
    ipcon_create(&ipcon);

    // Create device object
    Barometer b;
    barometer_create(&b, UID, &ipcon);

    // Connect to brickd
    if(ipcon_connect(&ipcon, HOST, PORT) < 0) {
        fprintf(stderr, "Could not connect\n");
        return 1;
    }
    // Don't use device before ipcon is connected

    // Get threshold callbacks with a debounce time of 10 seconds (10000ms)
    barometer_set_debounce_period(&b, 10000);

    // Register air pressure reached callback to function cb_air_pressure_reached
    barometer_register_callback(&b,
                                BAROMETER_CALLBACK_AIR_PRESSURE_REACHED,
                                (void (*)(void))cb_air_pressure_reached,
                                NULL);

    // Configure threshold for air pressure "greater than 1025 hPa"
    barometer_set_air_pressure_callback_threshold(&b, '>', 1025*1000, 0);

    printf("Press key to exit\n");
    getchar();
    barometer_destroy(&b);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

API¶

Every function of the C/C++ bindings returns an integer which describes an error code. Data returned from the device, when a getter is called, is handled via output parameters. These parameters are labeled with the ret_ prefix.

Possible error codes are:

E_OK = 0
E_TIMEOUT = -1
E_NO_STREAM_SOCKET = -2
E_HOSTNAME_INVALID = -3
E_NO_CONNECT = -4
E_NO_THREAD = -5
E_NOT_ADDED = -6 (unused since C/C++ bindings version 2.0.0)
E_ALREADY_CONNECTED = -7
E_NOT_CONNECTED = -8
E_INVALID_PARAMETER = -9
E_NOT_SUPPORTED = -10
E_UNKNOWN_ERROR_CODE = -11
E_STREAM_OUT_OF_SYNC = -12
E_INVALID_UID = -13
E_NON_ASCII_CHAR_IN_SECRET = -14
E_WRONG_DEVICE_TYPE = -15
E_DEVICE_REPLACED = -16
E_WRONG_RESPONSE_LENGTH = -17

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions¶

void barometer_create(Barometer *barometer, const char *uid, IPConnection *ipcon)¶

Parameters:	barometer – Type: Barometer * uid – Type: const char * ipcon – Type: IPConnection *

Creates the device object barometer with the unique device ID uid and adds it to the IPConnection ipcon:

Barometer barometer;
barometer_create(&barometer, "YOUR_DEVICE_UID", &ipcon);

This device object can be used after the IP connection has been connected.

void barometer_destroy(Barometer *barometer)¶

Parameters:	barometer – Type: Barometer *

Removes the device object barometer from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int barometer_get_air_pressure(Barometer *barometer, int32_t *ret_air_pressure)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_air_pressure – Type: int32_t, Unit: 1/1000 hPa, Range: [10000 to 1200000]
Returns:	error_code – Type: int

Returns the air pressure of the air pressure sensor.

If you want to get the air pressure periodically, it is recommended to use the BAROMETER_CALLBACK_AIR_PRESSURE callback and set the period with barometer_set_air_pressure_callback_period().

int barometer_get_altitude(Barometer *barometer, int32_t *ret_altitude)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_altitude – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1]
Returns:	error_code – Type: int

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 barometer_set_reference_air_pressure().

If you want to get the altitude periodically, it is recommended to use the BAROMETER_CALLBACK_ALTITUDE callback and set the period with barometer_set_altitude_callback_period().

int barometer_set_reference_air_pressure(Barometer *barometer, int32_t air_pressure)¶

Parameters:	barometer – Type: Barometer * air_pressure – Type: int32_t, Unit: 1/1000 hPa, Range: [0, 10000 to 1200000], Default: 1013250
Returns:	error_code – Type: int

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.

int barometer_get_reference_air_pressure(Barometer *barometer, int32_t *ret_air_pressure)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_air_pressure – Type: int32_t, Unit: 1/1000 hPa, Range: [10000 to 1200000], Default: 1013250
Returns:	error_code – Type: int

Returns the reference air pressure as set by barometer_set_reference_air_pressure().

Advanced Functions¶

int barometer_get_chip_temperature(Barometer *barometer, int16_t *ret_temperature)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_temperature – Type: int16_t, Unit: 1/100 °C, Range: [-4000 to 8500]
Returns:	error_code – Type: int

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.

int barometer_set_averaging(Barometer *barometer, uint8_t moving_average_pressure, uint8_t average_pressure, uint8_t average_temperature)¶

Parameters:	barometer – Type: Barometer * moving_average_pressure – Type: uint8_t, Range: [0 to 25], Default: 25 average_pressure – Type: uint8_t, Range: [0 to 10], Default: 10 average_temperature – Type: uint8_t, Range: [0 to 255], Default: 10
Returns:	error_code – Type: int

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.

New in version 2.0.1 (Plugin).

int barometer_get_averaging(Barometer *barometer, uint8_t *ret_moving_average_pressure, uint8_t *ret_average_pressure, uint8_t *ret_average_temperature)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_moving_average_pressure – Type: uint8_t, Range: [0 to 25], Default: 25 ret_average_pressure – Type: uint8_t, Range: [0 to 10], Default: 10 ret_average_temperature – Type: uint8_t, Range: [0 to 255], Default: 10
Returns:	error_code – Type: int

Returns the averaging configuration as set by barometer_set_averaging().

New in version 2.0.1 (Plugin).

int barometer_set_i2c_mode(Barometer *barometer, uint8_t mode)¶

Parameters:	barometer – Type: Barometer * mode – Type: uint8_t, Range: See constants, Default: 0
Returns:	error_code – Type: int

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:

BAROMETER_I2C_MODE_FAST = 0
BAROMETER_I2C_MODE_SLOW = 1

New in version 2.0.3 (Plugin).

int barometer_get_i2c_mode(Barometer *barometer, uint8_t *ret_mode)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_mode – Type: uint8_t, Range: See constants, Default: 0
Returns:	error_code – Type: int

Returns the I2C mode as set by barometer_set_i2c_mode().

The following constants are available for this function:

For ret_mode:

BAROMETER_I2C_MODE_FAST = 0
BAROMETER_I2C_MODE_SLOW = 1

New in version 2.0.3 (Plugin).

int barometer_get_identity(Barometer *barometer, char ret_uid[8], char ret_connected_uid[8], char *ret_position, uint8_t ret_hardware_version[3], uint8_t ret_firmware_version[3], uint16_t *ret_device_identifier)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_uid – Type: char[8] ret_connected_uid – Type: char[8] ret_position – Type: char, Range: ['a' to 'h', 'i', 'z'] ret_hardware_version – Type: uint8_t[3] 0: major – Type: uint8_t, Range: [0 to 255] 1: minor – Type: uint8_t, Range: [0 to 255] 2: revision – Type: uint8_t, Range: [0 to 255] ret_firmware_version – Type: uint8_t[3] 0: major – Type: uint8_t, Range: [0 to 255] 1: minor – Type: uint8_t, Range: [0 to 255] 2: revision – Type: uint8_t, Range: [0 to 255] ret_device_identifier – Type: uint16_t, Range: [0 to 2¹⁶ - 1]
Returns:	error_code – Type: int

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). The Raspberry Pi HAT (Zero) Brick is always at position 'i' and the Bricklet connected to an Isolator Bricklet is always as 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¶

void barometer_register_callback(Barometer *barometer, int16_t callback_id, void (*function)(void), void *user_data)¶

Parameters:	barometer – Type: Barometer * callback_id – Type: int16_t function – Type: void ()(void) user_data* – Type: void *

Registers the given function with the given callback_id. The user_data will be passed as the last parameter to the function.

The available callback IDs with corresponding function signatures are listed below.

int barometer_set_air_pressure_callback_period(Barometer *barometer, uint32_t period)¶

Parameters:	barometer – Type: Barometer * period – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	error_code – Type: int

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

The BAROMETER_CALLBACK_AIR_PRESSURE callback is only triggered if the air pressure has changed since the last triggering.

int barometer_get_air_pressure_callback_period(Barometer *barometer, uint32_t *ret_period)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_period – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	error_code – Type: int

Returns the period as set by barometer_set_air_pressure_callback_period().

int barometer_set_altitude_callback_period(Barometer *barometer, uint32_t period)¶

Parameters:	barometer – Type: Barometer * period – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	error_code – Type: int

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

The BAROMETER_CALLBACK_ALTITUDE callback is only triggered if the altitude has changed since the last triggering.

int barometer_get_altitude_callback_period(Barometer *barometer, uint32_t *ret_period)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_period – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0
Returns:	error_code – Type: int

Returns the period as set by barometer_set_altitude_callback_period().

int barometer_set_air_pressure_callback_threshold(Barometer *barometer, char option, int32_t min, int32_t max)¶

Parameters:	barometer – Type: Barometer * option – Type: char, Range: See constants, Default: 'x' min – Type: int32_t, Unit: 1/1000 hPa, Range: [-2³¹ to 2³¹ - 1], Default: 0 max – Type: int32_t, Unit: 1/1000 hPa, Range: [-2³¹ to 2³¹ - 1], Default: 0
Returns:	error_code – Type: int

Sets the thresholds for the BAROMETER_CALLBACK_AIR_PRESSURE_REACHED 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:

BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BAROMETER_THRESHOLD_OPTION_GREATER = '>'

int barometer_get_air_pressure_callback_threshold(Barometer *barometer, char *ret_option, int32_t *ret_min, int32_t *ret_max)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_option – Type: char, Range: See constants, Default: 'x' ret_min – Type: int32_t, Unit: 1/1000 hPa, Range: [-2³¹ to 2³¹ - 1], Default: 0 ret_max – Type: int32_t, Unit: 1/1000 hPa, Range: [-2³¹ to 2³¹ - 1], Default: 0
Returns:	error_code – Type: int

Returns the threshold as set by barometer_set_air_pressure_callback_threshold().

The following constants are available for this function:

For ret_option:

BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BAROMETER_THRESHOLD_OPTION_GREATER = '>'

int barometer_set_altitude_callback_threshold(Barometer *barometer, char option, int32_t min, int32_t max)¶

Parameters:	barometer – Type: Barometer * option – Type: char, Range: See constants, Default: 'x' min – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1], Default: 0 max – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1], Default: 0
Returns:	error_code – Type: int

Sets the thresholds for the BAROMETER_CALLBACK_ALTITUDE_REACHED 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:

BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BAROMETER_THRESHOLD_OPTION_GREATER = '>'

int barometer_get_altitude_callback_threshold(Barometer *barometer, char *ret_option, int32_t *ret_min, int32_t *ret_max)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_option – Type: char, Range: See constants, Default: 'x' ret_min – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1], Default: 0 ret_max – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1], Default: 0
Returns:	error_code – Type: int

Returns the threshold as set by barometer_set_altitude_callback_threshold().

The following constants are available for this function:

For ret_option:

BAROMETER_THRESHOLD_OPTION_OFF = 'x'
BAROMETER_THRESHOLD_OPTION_OUTSIDE = 'o'
BAROMETER_THRESHOLD_OPTION_INSIDE = 'i'
BAROMETER_THRESHOLD_OPTION_SMALLER = '<'
BAROMETER_THRESHOLD_OPTION_GREATER = '>'

int barometer_set_debounce_period(Barometer *barometer, uint32_t debounce)¶

Parameters:	barometer – Type: Barometer * debounce – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100
Returns:	error_code – Type: int

Sets the period with which the threshold callbacks

BAROMETER_CALLBACK_AIR_PRESSURE_REACHED,
BAROMETER_CALLBACK_ALTITUDE_REACHED

are triggered, if the thresholds

barometer_set_air_pressure_callback_threshold(),
barometer_set_altitude_callback_threshold()

keep being reached.

int barometer_get_debounce_period(Barometer *barometer, uint32_t *ret_debounce)¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_debounce – Type: uint32_t, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 100
Returns:	error_code – Type: int

Returns the debounce period as set by barometer_set_debounce_period().

Callbacks¶

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the barometer_register_callback() function:

void my_callback(int value, void *user_data) {
    printf("Value: %d\n", value);
}

barometer_register_callback(&barometer,
                            BAROMETER_CALLBACK_EXAMPLE,
                            (void (*)(void))my_callback,
                            NULL);

The available constants with corresponding function signatures 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.

BAROMETER_CALLBACK_AIR_PRESSURE¶

void callback(int32_t air_pressure, void *user_data)

Callback Parameters:	air_pressure – Type: int32_t, Unit: 1/1000 hPa, Range: [10000 to 1200000] user_data – Type: void *

This callback is triggered periodically with the period that is set by barometer_set_air_pressure_callback_period(). The parameter is the air pressure of the air pressure sensor.

The BAROMETER_CALLBACK_AIR_PRESSURE callback is only triggered if the air pressure has changed since the last triggering.

BAROMETER_CALLBACK_ALTITUDE¶

void callback(int32_t altitude, void *user_data)

Callback Parameters:	altitude – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1] user_data – Type: void *

This callback is triggered periodically with the period that is set by barometer_set_altitude_callback_period(). The parameter is the altitude of the air pressure sensor.

The BAROMETER_CALLBACK_ALTITUDE callback is only triggered if the altitude has changed since the last triggering.

BAROMETER_CALLBACK_AIR_PRESSURE_REACHED¶

void callback(int32_t air_pressure, void *user_data)

Callback Parameters:	air_pressure – Type: int32_t, Unit: 1/1000 hPa, Range: [10000 to 1200000] user_data – Type: void *

This callback is triggered when the threshold as set by barometer_set_air_pressure_callback_threshold() 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 barometer_set_debounce_period().

BAROMETER_CALLBACK_ALTITUDE_REACHED¶

void callback(int32_t altitude, void *user_data)

Callback Parameters:	altitude – Type: int32_t, Unit: 1 cm, Range: [-2³¹ to 2³¹ - 1] user_data – Type: void *

This callback is triggered when the threshold as set by barometer_set_altitude_callback_threshold() 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 barometer_set_debounce_period().

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.

int barometer_get_api_version(Barometer *barometer, uint8_t ret_api_version[3])¶

Parameters:	barometer – Type: Barometer *
Output Parameters:	ret_api_version – Type: uint8_t[3] 0: major – Type: uint8_t, Range: [0 to 255] 1: minor – Type: uint8_t, Range: [0 to 255] 2: revision – Type: uint8_t, Range: [0 to 255]
Returns:	error_code – Type: int

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.

int barometer_get_response_expected(Barometer *barometer, uint8_t function_id, bool *ret_response_expected)¶

Parameters:	barometer – Type: Barometer * function_id – Type: uint8_t, Range: See constants
Output Parameters:	ret_response_expected – Type: bool
Returns:	error_code – Type: int

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 barometer_set_response_expected(). 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 function_id:

BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
BAROMETER_FUNCTION_SET_DEBOUNCE_PERIOD = 11
BAROMETER_FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
BAROMETER_FUNCTION_SET_AVERAGING = 20
BAROMETER_FUNCTION_SET_I2C_MODE = 22

int barometer_set_response_expected(Barometer *barometer, uint8_t function_id, bool response_expected)¶

Parameters:	barometer – Type: Barometer * function_id – Type: uint8_t, Range: See constants response_expected – Type: bool
Returns:	error_code – Type: int

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.

The following constants are available for this function:

For function_id:

BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_PERIOD = 3
BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_PERIOD = 5
BAROMETER_FUNCTION_SET_AIR_PRESSURE_CALLBACK_THRESHOLD = 7
BAROMETER_FUNCTION_SET_ALTITUDE_CALLBACK_THRESHOLD = 9
BAROMETER_FUNCTION_SET_DEBOUNCE_PERIOD = 11
BAROMETER_FUNCTION_SET_REFERENCE_AIR_PRESSURE = 13
BAROMETER_FUNCTION_SET_AVERAGING = 20
BAROMETER_FUNCTION_SET_I2C_MODE = 22

int barometer_set_response_expected_all(Barometer *barometer, bool response_expected)¶

Parameters:	barometer – Type: Barometer * response_expected – Type: bool
Returns:	error_code – Type: int

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

Constants¶

BAROMETER_DEVICE_IDENTIFIER¶

This constant is used to identify a Barometer Bricklet.

The barometer_get_identity() function and the IPCON_CALLBACK_ENUMERATE callback of the IP Connection have a device_identifier parameter to specify the Brick's or Bricklet's type.

BAROMETER_DEVICE_DISPLAY_NAME¶: This constant represents the human readable name of a Barometer Bricklet.