C/C++ - Barometer Bricklet 2.0

This is the description of the C/C++ API bindings for the Barometer Bricklet 2.0. General information and technical specifications for the Barometer Bricklet 2.0 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)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet 2.0

// 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 mbar\n", air_pressure/1000.0);
}

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

    // Create device object
    BarometerV2 b;
    barometer_v2_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_v2_register_callback(&b,
                                   BAROMETER_V2_CALLBACK_AIR_PRESSURE,
                                   (void *)cb_air_pressure,
                                   NULL);

    // Set period for air pressure callback to 1s (1000ms) without a threshold
    barometer_v2_set_air_pressure_callback_configuration(&b, 1000, false, 'x', 0, 0);

    printf("Press key to exit\n");
    getchar();
    barometer_v2_destroy(&b);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Simple

Download (example_simple.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet 2.0

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

    // Create device object
    BarometerV2 b;
    barometer_v2_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_v2_get_air_pressure(&b, &air_pressure) < 0) {
        fprintf(stderr, "Could not get air pressure, probably timeout\n");
        return 1;
    }

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

    // Get current altitude
    int32_t altitude;
    if(barometer_v2_get_altitude(&b, &altitude) < 0) {
        fprintf(stderr, "Could not get altitude, probably timeout\n");
        return 1;
    }

    printf("Altitude: %f m\n", altitude/1000.0);

    printf("Press key to exit\n");
    getchar();
    barometer_v2_destroy(&b);
    ipcon_destroy(&ipcon); // Calls ipcon_disconnect internally
    return 0;
}

Threshold

Download (example_threshold.c)

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#include <stdio.h>

#include "ip_connection.h"
#include "bricklet_barometer_v2.h"

#define HOST "localhost"
#define PORT 4223
#define UID "XYZ" // Change XYZ to the UID of your Barometer Bricklet 2.0

// 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 mbar\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
    BarometerV2 b;
    barometer_v2_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_v2_register_callback(&b,
                                   BAROMETER_V2_CALLBACK_AIR_PRESSURE,
                                   (void *)cb_air_pressure,
                                   NULL);

    // Configure threshold for air pressure "greater than 1025 mbar"
    // with a debounce period of 1s (1000ms)
    barometer_v2_set_air_pressure_callback_configuration(&b, 1000, false, '>', 1025*1000, 0);

    printf("Press key to exit\n");
    getchar();
    barometer_v2_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 call by reference. 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 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

as defined in ip_connection.h.

All functions listed below are thread-safe.

Basic Functions

void barometer_v2_create(BarometerV2 *barometer_v2, const char *uid, IPConnection *ipcon)

Creates the device object barometer_v2 with the unique device ID uid and adds it to the IPConnection ipcon:

BarometerV2 barometer_v2;
barometer_v2_create(&barometer_v2, "YOUR_DEVICE_UID", &ipcon);

This device object can be used after the IP connection has been connected (see examples above).

void barometer_v2_destroy(BarometerV2 *barometer_v2)

Removes the device object barometer_v2 from its IPConnection and destroys it. The device object cannot be used anymore afterwards.

int barometer_v2_get_air_pressure(BarometerV2 *barometer_v2, int32_t *ret_air_pressure)

Returns the measured air pressure. The value has a range of 260000 to 1260000 and is given in mbar/1000, i.e. a value of 1001092 means that an air pressure of 1001.092 mbar is measured.

If you want to get the value periodically, it is recommended to use the BAROMETER_V2_CALLBACK_AIR_PRESSURE callback. You can set the callback configuration with barometer_v2_set_air_pressure_callback_configuration().

int barometer_v2_get_altitude(BarometerV2 *barometer_v2, int32_t *ret_altitude)

Returns the relative altitude of the air pressure sensor. The value is given in mm and is calculated based on the difference between the current air pressure and the reference air pressure that can be set with barometer_v2_set_reference_air_pressure().

If you want to get the value periodically, it is recommended to use the BAROMETER_V2_CALLBACK_ALTITUDE callback. You can set the callback configuration with barometer_v2_set_altitude_callback_configuration().

int barometer_v2_get_temperature(BarometerV2 *barometer_v2, int32_t *ret_temperature)

Returns the temperature of the air pressure sensor. The value has a range of -4000 to 8500 and is given in °C/100, i.e. a value of 2007 means that a temperature of 20.07 °C is measured.

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 2.0 or the Temperature IR Bricklet 2.0.

If you want to get the value periodically, it is recommended to use the BAROMETER_V2_CALLBACK_TEMPERATURE callback. You can set the callback configuration with barometer_v2_set_temperature_callback_configuration().

int barometer_v2_set_moving_average_configuration(BarometerV2 *barometer_v2, uint16_t moving_average_length_air_pressure, uint16_t moving_average_length_temperature)

Sets the length of a moving averaging for the air pressure and temperature measurements.

Setting the length to 1 will turn the averaging off. With less averaging, there is more noise on the data.

The range for the averaging is 1-1000.

If you want to do long term measurements the longest moving average will give the cleanest results.

The default value is 100.

int barometer_v2_get_moving_average_configuration(BarometerV2 *barometer_v2, uint16_t *ret_moving_average_length_air_pressure, uint16_t *ret_moving_average_length_temperature)

Returns the moving average configuration as set by barometer_v2_set_moving_average_configuration().

int barometer_v2_set_reference_air_pressure(BarometerV2 *barometer_v2, int32_t air_pressure)

Sets the reference air pressure in mbar/1000 for the altitude calculation. Valid values are between 260000 and 1260000. Setting the reference to the current air pressure results in a calculated altitude of 0mm. 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.

The default value is 1013.25mbar.

int barometer_v2_get_reference_air_pressure(BarometerV2 *barometer_v2, int32_t *ret_air_pressure)

Returns the reference air pressure as set by barometer_v2_set_reference_air_pressure().

Advanced Functions

int barometer_v2_set_calibration(BarometerV2 *barometer_v2, int32_t measured_air_pressure, int32_t actual_air_pressure)

Sets the one point calibration (OPC) values for the air pressure measurement.

Before the Bricklet can be calibrated any previous calibration has to be removed by setting measured air pressure and actual air pressure to 0.

Then the current air pressure has to be measured using the Bricklet (measured air pressure) and with and accurate reference barometer (actual air pressure) at the same time and passed to this function in mbar/1000.

After proper calibration the air pressure measurement can achieve an accuracy up to 0.2 mbar.

The calibration is saved in the EEPROM of the Bricklet and only needs to be configured once.

int barometer_v2_get_calibration(BarometerV2 *barometer_v2, int32_t *ret_measured_air_pressure, int32_t *ret_actual_air_pressure)

Returns the air pressure one point calibration values as set by barometer_v2_set_calibration().

int barometer_v2_set_sensor_configuration(BarometerV2 *barometer_v2, uint8_t data_rate, uint8_t air_pressure_low_pass_filter)

Configures the data rate and air pressure low pass filter. The low pass filter cut-off frequency (if enabled) can be set to 1/9th or 1/20th of the configure data rate to decrease the noise on the air pressure data.

The low pass filter configuration only applies to the air pressure measurement. There is no low pass filter for the temperature measurement.

A higher data rate will result in a less precise temperature because of self-heating of the sensor. If the accuracy of the temperature reading is important to you, we would recommend the 1Hz data rate.

The default values are 50Hz data rate and 1/9th low pass filter.

The following defines are available for this function:

  • BAROMETER_V2_DATA_RATE_OFF = 0
  • BAROMETER_V2_DATA_RATE_1HZ = 1
  • BAROMETER_V2_DATA_RATE_10HZ = 2
  • BAROMETER_V2_DATA_RATE_25HZ = 3
  • BAROMETER_V2_DATA_RATE_50HZ = 4
  • BAROMETER_V2_DATA_RATE_75HZ = 5
  • BAROMETER_V2_LOW_PASS_FILTER_OFF = 0
  • BAROMETER_V2_LOW_PASS_FILTER_1_9TH = 1
  • BAROMETER_V2_LOW_PASS_FILTER_1_20TH = 2
int barometer_v2_get_sensor_configuration(BarometerV2 *barometer_v2, uint8_t *ret_data_rate, uint8_t *ret_air_pressure_low_pass_filter)

Returns the sensor configuration as set by barometer_v2_set_sensor_configuration().

The following defines are available for this function:

  • BAROMETER_V2_DATA_RATE_OFF = 0
  • BAROMETER_V2_DATA_RATE_1HZ = 1
  • BAROMETER_V2_DATA_RATE_10HZ = 2
  • BAROMETER_V2_DATA_RATE_25HZ = 3
  • BAROMETER_V2_DATA_RATE_50HZ = 4
  • BAROMETER_V2_DATA_RATE_75HZ = 5
  • BAROMETER_V2_LOW_PASS_FILTER_OFF = 0
  • BAROMETER_V2_LOW_PASS_FILTER_1_9TH = 1
  • BAROMETER_V2_LOW_PASS_FILTER_1_20TH = 2
int barometer_v2_get_api_version(BarometerV2 *barometer_v2, uint8_t ret_api_version[3])

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.

int barometer_v2_get_response_expected(BarometerV2 *barometer_v2, uint8_t function_id, bool *ret_response_expected)

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_v2_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 send and errors are silently ignored, because they cannot be detected.

See barometer_v2_set_response_expected() for the list of function ID defines available for this function.

int barometer_v2_set_response_expected(BarometerV2 *barometer_v2, uint8_t function_id, bool response_expected)

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 defines are available for this function:

  • BAROMETER_V2_FUNCTION_SET_AIR_PRESSURE_CALLBACK_CONFIGURATION = 2
  • BAROMETER_V2_FUNCTION_SET_ALTITUDE_CALLBACK_CONFIGURATION = 6
  • BAROMETER_V2_FUNCTION_SET_TEMPERATURE_CALLBACK_CONFIGURATION = 10
  • BAROMETER_V2_FUNCTION_SET_MOVING_AVERAGE_CONFIGURATION = 13
  • BAROMETER_V2_FUNCTION_SET_REFERENCE_AIR_PRESSURE = 15
  • BAROMETER_V2_FUNCTION_SET_CALIBRATION = 17
  • BAROMETER_V2_FUNCTION_SET_SENSOR_CONFIGURATION = 19
  • BAROMETER_V2_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BAROMETER_V2_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BAROMETER_V2_FUNCTION_RESET = 243
  • BAROMETER_V2_FUNCTION_WRITE_UID = 248
int barometer_v2_set_response_expected_all(BarometerV2 *barometer_v2, bool response_expected)

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

int barometer_v2_get_spitfp_error_count(BarometerV2 *barometer_v2, uint32_t *ret_error_count_ack_checksum, uint32_t *ret_error_count_message_checksum, uint32_t *ret_error_count_frame, uint32_t *ret_error_count_overflow)

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.

int barometer_v2_set_bootloader_mode(BarometerV2 *barometer_v2, uint8_t mode, uint8_t *ret_status)

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 defines are available for this function:

  • BAROMETER_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • BAROMETER_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BAROMETER_V2_BOOTLOADER_STATUS_OK = 0
  • BAROMETER_V2_BOOTLOADER_STATUS_INVALID_MODE = 1
  • BAROMETER_V2_BOOTLOADER_STATUS_NO_CHANGE = 2
  • BAROMETER_V2_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BAROMETER_V2_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BAROMETER_V2_BOOTLOADER_STATUS_CRC_MISMATCH = 5
int barometer_v2_get_bootloader_mode(BarometerV2 *barometer_v2, uint8_t *ret_mode)

Returns the current bootloader mode, see barometer_v2_set_bootloader_mode().

The following defines are available for this function:

  • BAROMETER_V2_BOOTLOADER_MODE_BOOTLOADER = 0
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE = 1
  • BAROMETER_V2_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BAROMETER_V2_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
int barometer_v2_set_write_firmware_pointer(BarometerV2 *barometer_v2, uint32_t pointer)

Sets the firmware pointer for barometer_v2_write_firmware(). 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.

int barometer_v2_write_firmware(BarometerV2 *barometer_v2, uint8_t data[64], uint8_t *ret_status)

Writes 64 Bytes of firmware at the position as written by barometer_v2_set_write_firmware_pointer() 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.

int barometer_v2_set_status_led_config(BarometerV2 *barometer_v2, uint8_t config)

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 defines are available for this function:

  • BAROMETER_V2_STATUS_LED_CONFIG_OFF = 0
  • BAROMETER_V2_STATUS_LED_CONFIG_ON = 1
  • BAROMETER_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BAROMETER_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int barometer_v2_get_status_led_config(BarometerV2 *barometer_v2, uint8_t *ret_config)

Returns the configuration as set by barometer_v2_set_status_led_config()

The following defines are available for this function:

  • BAROMETER_V2_STATUS_LED_CONFIG_OFF = 0
  • BAROMETER_V2_STATUS_LED_CONFIG_ON = 1
  • BAROMETER_V2_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BAROMETER_V2_STATUS_LED_CONFIG_SHOW_STATUS = 3
int barometer_v2_get_chip_temperature(BarometerV2 *barometer_v2, int16_t *ret_temperature)

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.

int barometer_v2_reset(BarometerV2 *barometer_v2)

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!

int barometer_v2_write_uid(BarometerV2 *barometer_v2, uint32_t uid)

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.

int barometer_v2_read_uid(BarometerV2 *barometer_v2, uint32_t *ret_uid)

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

int barometer_v2_get_identity(BarometerV2 *barometer_v2, 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)

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

void barometer_v2_register_callback(BarometerV2 *barometer_v2, int16_t callback_id, void *function, void *user_data)

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_v2_set_air_pressure_callback_configuration(BarometerV2 *barometer_v2, uint32_t period, bool value_has_to_change, char option, int32_t min, int32_t max)

The period in ms is the period with which the BAROMETER_V2_CALLBACK_AIR_PRESSURE 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 BAROMETER_V2_CALLBACK_AIR_PRESSURE 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 defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'
int barometer_v2_get_air_pressure_callback_configuration(BarometerV2 *barometer_v2, uint32_t *ret_period, bool *ret_value_has_to_change, char *ret_option, int32_t *ret_min, int32_t *ret_max)

Returns the callback configuration as set by barometer_v2_set_air_pressure_callback_configuration().

The following defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'
int barometer_v2_set_altitude_callback_configuration(BarometerV2 *barometer_v2, uint32_t period, bool value_has_to_change, char option, int32_t min, int32_t max)

The period in ms is the period with which the BAROMETER_V2_CALLBACK_ALTITUDE 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 BAROMETER_V2_CALLBACK_ALTITUDE 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 defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'
int barometer_v2_get_altitude_callback_configuration(BarometerV2 *barometer_v2, uint32_t *ret_period, bool *ret_value_has_to_change, char *ret_option, int32_t *ret_min, int32_t *ret_max)

Returns the callback configuration as set by barometer_v2_set_altitude_callback_configuration().

The following defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'
int barometer_v2_set_temperature_callback_configuration(BarometerV2 *barometer_v2, uint32_t period, bool value_has_to_change, char option, int32_t min, int32_t max)

The period in ms is the period with which the BAROMETER_V2_CALLBACK_TEMPERATURE 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 BAROMETER_V2_CALLBACK_TEMPERATURE 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 defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'
int barometer_v2_get_temperature_callback_configuration(BarometerV2 *barometer_v2, uint32_t *ret_period, bool *ret_value_has_to_change, char *ret_option, int32_t *ret_min, int32_t *ret_max)

Returns the callback configuration as set by barometer_v2_set_temperature_callback_configuration().

The following defines are available for this function:

  • BAROMETER_V2_THRESHOLD_OPTION_OFF = 'x'
  • BAROMETER_V2_THRESHOLD_OPTION_OUTSIDE = 'o'
  • BAROMETER_V2_THRESHOLD_OPTION_INSIDE = 'i'
  • BAROMETER_V2_THRESHOLD_OPTION_SMALLER = '<'
  • BAROMETER_V2_THRESHOLD_OPTION_GREATER = '>'

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the barometer_v2_register_callback() function. The parameters consist of the device object, the callback ID, the callback function and optional user data:

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

barometer_v2_register_callback(&barometer_v2, BAROMETER_V2_CALLBACK_EXAMPLE, (void *)my_callback, NULL);

The available constants with corresponding callback 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_V2_CALLBACK_AIR_PRESSURE
void callback(int32_t air_pressure, void *user_data)

This callback is triggered periodically according to the configuration set by barometer_v2_set_air_pressure_callback_configuration().

The parameter is the same as barometer_v2_get_air_pressure().

BAROMETER_V2_CALLBACK_ALTITUDE
void callback(int32_t altitude, void *user_data)

This callback is triggered periodically according to the configuration set by barometer_v2_set_altitude_callback_configuration().

The parameter is the same as barometer_v2_get_altitude().

BAROMETER_V2_CALLBACK_TEMPERATURE
void callback(int32_t temperature, void *user_data)

This callback is triggered periodically according to the configuration set by barometer_v2_set_temperature_callback_configuration().

The parameter is the same as barometer_v2_get_temperature().

Constants

BAROMETER_V2_DEVICE_IDENTIFIER

This constant is used to identify a Barometer Bricklet 2.0.

The barometer_v2_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_V2_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Barometer Bricklet 2.0.