Bluetooth Mesh sensors

Note

A new sensor API is introduced as of nRF Connect SDK v2.6.0. The old API is deprecated, but still available by enabling the Kconfig option CONFIG_BT_MESH_SENSOR_USE_LEGACY_SENSOR_VALUE. The Kconfig option is enabled by default in the deprecation period. See the documentation for nRF Connect SDK versions prior to v2.6.0 for documentation about the old sensor API.

The Bluetooth® Mesh specification provides a common scheme for representing all sensors. A single Bluetooth Mesh sensor instance represents a single physical sensor, and a mesh device may present any number of sensors to the network through a Sensor Server model. Sensors represent their measurements as a list of sensor channels, as described by the sensor’s assigned type.

Sensors are accessed through the Sensor models, which are documented separately:

Sensor models
- Sensor Server
- Sensor Client

Note

Several floating point computations are done internally in the stack when using the sensor API. It is recommended to enable the CONFIG_FPU Kconfig option to improve the performance of these computations.

Basic example 

A sensor reporting the device operating temperature could combine the Bluetooth Mesh Present Device Operating Temperature sensor type with the on-chip TEMP_NRF5 temperature sensor driver:

static const struct device *dev = DEVICE_DT_GET_ONE(nordic_nrf_temp);

static int temp_get(struct bt_mesh_sensor *sensor,
                    struct bt_mesh_msg_ctx *ctx,
                    struct bt_mesh_sensor_value *rsp)
{
    struct sensor_value value;
    int err;

    sensor_sample_fetch(dev);
    err = sensor_channel_get(dev, SENSOR_CHAN_DIE_TEMP, &value);
    if (err) {
        return err;
    }
    return bt_mesh_sensor_value_from_sensor_value(&value, rsp);
}

struct bt_mesh_sensor temp_sensor = {
    .type = &bt_mesh_sensor_present_dev_op_temp,
    .get = temp_get,
};

void init(void)
{
     __ASSERT(device_is_ready(dev), "Sensor device not ready");
}

Additionally, a pointer to the temp_sensor structure should be passed to a Sensor Server to be exposed to the mesh. See Sensor Server for details.

Sensor values 

Sensor values are represented in the API using bt_mesh_sensor_value. This contains the raw sensor value, encoded according to a certain Bluetooth GATT Characteristic, and a pointer to bt_mesh_sensor_format describing how that characteristic is encoded/decoded.

Applications will normally not access bt_mesh_sensor_value.raw or the members of bt_mesh_sensor_value.format directly. Instead, API functions for converting between bt_mesh_sensor_value and the values suitable for application use are used. An exception to this is when statically initializing bt_mesh_sensor_value at compile-time, in which case the API functions cannot be used.

The sensor API is built to integrate well with the Zephyr Sensors API, and provides functions for converting to and from sensor_value.

Sensor types 

Sensor types are the specification defined data types for the various Bluetooth Mesh sensor parameters. Each sensor type is assigned its own Device Property ID, as specified in the Bluetooth Mesh device properties specification. Like the Device Properties, the Sensor types are connected to a Bluetooth GATT Characteristic, which describes the unit, range, resolution and encoding scheme of the sensor type.

Note

The Bluetooth Mesh specification only allows sensor types that have a Device Property ID in the Bluetooth Mesh device properties specification. It’s not possible to represent vendor specific sensor values.

The sensor types may either be used as the data types of the sensor output values, or as configuration parameters for the sensors.

Sensor channels 

Each sensor type may consist of one or more channels. The list of sensor channels in each sensor type is immutable, and all channels must always have a valid value when the sensor data is passed around. This is slightly different from the sensor type representation in the Bluetooth Mesh specification, which represents multi-channel sensors as structures, rather than flat lists.

Each channel in a sensor type is represented by a single bt_mesh_sensor_value structure. This contains the raw value of the sensor value, and a pointer to bt_mesh_sensor_format used for encoding and decoding of the raw value.

Every sensor channel has a name and a unit, as listed in the sensor type documentation. The name and unit are only available if CONFIG_BT_MESH_SENSOR_LABELS option is set, and can aid in debugging and presentation of the sensor output. Both the channel name and unit is also listed in the documentation for each sensor type.

Most sensor values are reported as scalars with some scaling factor applied to them during encoding. This scaling factor and the encoded data type determines the resolution and range of the sensor data in a specific channel. For instance, if a sensor channel measuring electric current has a resolution of 0.5 Ampere, this is the highest resolution value other mesh devices will be able to read out from the sensor. Before encoding, the sensor values are rounded to their nearest available representation, so the following sensor value would be read as 7.5 Ampere:

struct bt_mesh_sensor_value sensor_val;

/* Sensor value: 7.3123 A */
(void)bt_mesh_sensor_value_from_float(
    &bt_mesh_sensor_format_electric_current,
    7.3123f, &sensor_val);

Various other encoding schemes are used to represent non-scalars. See the documentation or specification for the individual sensor channels for more details.

Sensor series types 

The sensor series functionality may be used for all sensor types. However, some sensor types are made specifically for being used in a sensor series. These sensor types have one primary channel containing the sensor data and two secondary channels that denote some interval in which the primary channel’s data is captured. Together, the three channels are able to represent historical sensor data as a histogram, and Sensor Client models may request access to specific measurement spans from a Sensor Server model.

The unit of the measurement span is defined by the sensor type, and will typically be a time interval or a range of operational parameters, like temperature or voltage level. For instance, the bt_mesh_sensor_rel_dev_energy_use_in_a_period_of_day sensor type represents the energy used by the device in specific periods of the day. The primary channel of this sensor type measures energy usage in kWh, and the secondary channels denote the timespan in which the specific energy usage was measured. A sensor of this type may be queried for specific measurement periods measured in hours, and should provide the registered energy usage only for the requested time span.

Sensor setting types 

Some sensor types are made specifically to act as sensor settings. These values are encoded the same way as other sensor types, but typically represent a configurable sensor setting or some specification value assigned to the sensor from the manufacturer. For instance, the bt_mesh_sensor_motion_threshold sensor type can be used to configure the sensitivity of a sensor reporting motion sensor data (bt_mesh_sensor_motion_sensed).

Typically, settings should only be meta data related to the sensor data type, but the API contains no restrictions for which sensor types can be used for sensor settings.

Available sensor types 

All available sensor types are collected in the Bluetooth Mesh sensor formats and sensor types module.

Sample data reporting 

Sensors may report their values to the mesh in three ways:

Unprompted publications
Periodic publication
Polling

Unprompted publications may be done at any time, and only includes the sensor data of a single sensor at a time. The application may generate an unprompted publication by calling bt_mesh_sensor_srv_sample(). This triggers the sensor’s bt_mesh_sensor.get callback, and only publishes if the sensor’s Delta threshold is satisfied.

Unprompted publications can also be forced by calling bt_mesh_sensor_srv_pub() directly.

Periodic publication is controlled by the Sensor Server model’s publication parameters, and configured by the Config models. The sensor Server model reports data for all its sensor instances periodically, at a rate determined by the sensors’ cadence. Every publication interval, the Server consolidates a list of sensors to include in the publication, and requests the most recent data from each. The combined data of all these sensors is published as a single message for other nodes in the mesh network.

If no publication parameters are configured for the Sensor Server model, Sensor Client models may poll the most recent sensor samples directly.

All three methods of reporting may be combined.

Cadence 

Each sensor may use the cadence state to control the rate at which their data is published. The sensor’s publication interval is defined as a divisor of the holding sensor Server’s publication interval that is always a power of two. Under normal circumstances, the sensor’s period divisor is always 1, and the sensor only publishes on the Server’s actual publication interval.

All single-channel sensors have a configurable fast cadence range that automatically controls the sensor cadence. If the sensor’s value is within its configured fast cadence range, the sensor engages the period divisor, and starts publishing with fast cadence.

The fast cadence range always starts at the cadence range low value, and spans to the cadence range high value. If the high value is lower than the low value, the effect is inverted, and the sensor operates at high cadence if its value is outside the range.

To prevent sensors from saturating the mesh network, each sensor also defines a minimum publication interval, which is always taken into account when performing the period division.

The period divisor, fast cadence range and minimum interval is configured by a Sensor Client model (through a Sensor Setup Server). The sensor’s cadence is automatically recalculated for every sample, based on its configuration.

Delta threshold 

All single channel sensors have a delta threshold state to aid the publication rate. The delta threshold state determines the smallest change in sensor value that should trigger a publication. Whenever a sensor value is published to the mesh network (through periodic publishing or otherwise), the sensor saves the value, and compares it to subsequent samples. Once a sample is sufficiently far away from the previously published value, it gets published.

The delta threshold works on both periodic publication and unprompted publications. If periodic publication is enabled and the minimum interval has expired, the sensor will periodically check whether the delta threshold has been breached, so that it can publish the value on the next periodic interval.

The delta threshold may either be specified as a percent wise change, or as an absolute delta. The percent wise change is always measured relatively to the previously published value, and allows the sensor to automatically scale its threshold to account for relative inaccuracy or noise.

The sensor has separate delta thresholds for positive and negative changes.

Descriptors 

Descriptors are optional meta information structures for every sensor. A sensor’s Descriptor contains parameters that may aid other mesh nodes in interpreting the data:

Tolerance
Sampling function
Measurement period
Update interval

The sensor descriptor is constant throughout the sensor’s lifetime. If the sensor has a descriptor, a pointer to it should be passed to bt_mesh_sensor.descriptor on init, as for example done in the code below:

static const struct bt_mesh_sensor_descriptor temp_sensor_descriptor = {
    .tolerance = {
        .negative = BT_MESH_SENSOR_TOLERANCE_ENCODE(0.75f)
        .positive = BT_MESH_SENSOR_TOLERANCE_ENCODE(3.5f)
    },
    .sampling_type = BT_MESH_SENSOR_SAMPLING_ARITHMETIC_MEAN,
    .period = 300,
    .update_interval = 50
};

struct bt_mesh_sensor temp_sensor = {
    .type = &bt_mesh_sensor_present_dev_op_temp,
    .get = temp_get,
    .descriptor = &temp_sensor_descriptor
};

See bt_mesh_sensor_descriptor for details.

Usage 

Sensors instances are generally static structures that are initialized at startup. Only the bt_mesh_sensor.type member is mandatory, the rest are optional. Apart from the Cadence and Descriptor states, all states are accessed through getter functions. The absence of a getter for a state marks it as not supported by the sensor.

Sensor data 

Sensor data is accessed through the bt_mesh_sensor.get callback, which is expected to fill the rsp parameter with the most recent sensor data and return a status code. Each sensor channel must be encoded according to the channel format. This can be done using one of the conversion functions bt_mesh_sensor_value_from_micro(), bt_mesh_sensor_value_from_float() or bt_mesh_sensor_value_from_sensor_value(). A pointer to the format for a given channel can be found through the bt_mesh_sensor pointer passed to the callback in a following way:

static int get_cb(struct bt_mesh_sensor *sensor,
                    struct bt_mesh_msg_ctx *ctx,
                    struct bt_mesh_sensor_value *rsp)
{
    /* Get the correct format to use for encoding rsp[0]: */
    const struct_bt_mesh_sensor_format *channel_0_format =
        sensor->type->channels[0].format;
}

The sensor data in the callback typically comes from a sensor using the Zephyr sensor API. The Zephyr sensor API records samples in two steps:

1. Tell the sensor to take a sample by calling sensor_sample_fetch(). 2. Read the recorded sample data with sensor_channel_get().

The first step may be done at any time. Typically, the sensor fetching is triggered by a timer, an external event or a sensor trigger, but it may be called in the get callback itself. Note that the get callback requires an immediate response, so if the sample fetching takes a significant amount of time, it should generally be done asynchronously. The method of sampling may be communicated to other mesh nodes through the sensor’s descriptor.

The read step would typically be done in the callback, to pass the sensor data to the mesh.

If the Sensor Server is configured to do periodic publishing, the get callback will be called for every publication interval. Publication may also be forced by calling bt_mesh_sensor_srv_sample(), which will trigger the get callback and publish only if the sensor value has changed.

Sensor series 

Sensor series data can be provided for all sensor types. To enable the sensor’s series data feature, bt_mesh_sensor_series.column_count must be specified and the sensor series bt_mesh_sensor_series.get callback must be implemented.

For sensor types with more than two channels, the series data is organized into a static set of columns, specified at init. The format of the column may be queried with bt_mesh_sensor_column_format_get().

The get callback gets called with an index of one of the columns, and is expected to fill the value parameter with sensor data for the specified column. If a Sensor Client requests a series of columns, the callback may be called repeatedly, requesting data from each column.

Example: A three-channel sensor (average ambient temperature in a period of day) as a sensor series:

/* Macro for statically initializing time_decihour_8.
 * Raw is computed by multiplying by 10 according to
 * the resolution specified in the GATT Specification
 * Supplement.
 */
#define TIME_DECIHOUR_8_INIT(_hours) {                \
    .format = &bt_mesh_sensor_format_time_decihour_8, \
    .raw = { (_hours) * 10 }                          \
}

#define COLUMN_INIT(_start, _width) { \
    TIME_DECIHOUR_8_INIT(_start),     \
    TIME_DECIHOUR_8_INIT(_width)      \
}

/* 4 columns representing different hours in a day */
static const struct bt_mesh_sensor_column columns[] = {
    COLUMN_INIT(0, 6),
    COLUMN_INIT(6, 6),
    COLUMN_INIT(12, 6),
    COLUMN_INIT(18, 6)
};

static struct bt_mesh_sensor temp_sensor = {
    .type = &bt_mesh_sensor_avg_amb_temp_in_day,
    .series = {
        columns,
        ARRAY_SIZE(columns),
        getter,
    },
};

/** Sensor data is divided into columns and filled elsewhere */
static float avg_temp[ARRAY_SIZE(columns)];

static int getter(struct bt_mesh_sensor *sensor, struct bt_mesh_msg_ctx *ctx,
                  uint32_t column_index, struct bt_mesh_sensor_value *value)
{
    int err = bt_mesh_sensor_value_from_float(
        sensor->type->channels[0].format, &avg_temp[column_index], &value[0]);

    if (err) {
        return err;
    }
    value[1] = columns[column_index].start;

    /* Compute end value from column start and width: */
    int64_t start, width;
    enum bt_mesh_sensor_value_status status;

    status = bt_mesh_sensor_value_to_micro(&columns[column_index].start, &start);
    if (!bt_mesh_sensor_status_is_numeric(status)) {
        return -EINVAL;
    }
    status = bt_mesh_sensor_value_to_micro(&columns[column_index].width, &width);
    if (!bt_mesh_sensor_value_status_is_numeric(status)) {
        return -EINVAL;
    }
    return bt_mesh_sensor_value_from_micro(
        bt_mesh_sensor_column_format_get(sensor),
        start + width, &value[2]);
}

Example: Single-channel sensor (motion sensed) as a sensor series:

#define COLUMN_COUNT 10

static struct bt_mesh_sensor motion_sensor = {
    .type = &bt_mesh_sensor_motion_sensed,
    .series = {
         /* Note: no column array necessary for 1 or 2 channel sensors */
         .column_count = COLUMN_COUNT,
         .get = getter,
     },
};

/** Sensor data is divided into columns and filled elsewhere */
static uint8_t motion[COLUMN_COUNT];

static int getter(struct bt_mesh_sensor *sensor, struct bt_mesh_msg_ctx *ctx,
                  uint32_t column_index, struct bt_mesh_sensor_value *value)
{
    return bt_mesh_sensor_value_from_micro(
        sensor->type->channels[0].format,
        motion[column_index] * 1000000LL, &value[0]);
}

Sensor settings 

The list of settings a sensor supports should be set on init. The list should be constant throughout the sensor’s lifetime, and may be declared const. Each entry in the list has a type and two access callbacks, and the list should only contain unique entry types.

The bt_mesh_sensor_setting.get callback is mandatory, while the bt_mesh_sensor_setting.set is optional, allowing for read-only entries. The value of the settings may change at runtime, even outside the set callback. New values may be rejected by returning a negative error code from the set callback. The following code is an example of adding a setting to a sensor:

static void motion_threshold_get(struct bt_mesh_sensor_srv *srv,
                                 struct bt_mesh_sensor *sensor,
                                 const struct bt_mesh_sensor_setting *setting,
                                 struct bt_mesh_msg_ctx *ctx,
                                 struct bt_mesh_sensor_value *rsp)
{
     /** Get the current threshold in an application defined way and
      *  store it in rsp.
      */
     get_threshold(rsp);
}

static int motion_threshold_set(struct bt_mesh_sensor_srv *srv,
                                struct bt_mesh_sensor *sensor,
                                const struct bt_mesh_sensor_setting *setting,
                                struct bt_mesh_msg_ctx *ctx,
                                const struct bt_mesh_sensor_value *value)
{
     /** Store incoming threshold in application-defined way.
      *  Return error code to reject set.
      */
     return set_threshold(value);
}

static const struct bt_mesh_sensor_setting settings[] = {
    {
        .type = &bt_mesh_sensor_motion_threshold,
        .get = motion_threshold_get,
        .set = motion_threshold_set,
    }
};

static struct bt_mesh_sensor motion_sensor = {
    .type = &bt_mesh_sensor_motion_sensed,
    .get = get_motion,
    .settings = {
        .list = settings,
        .count = ARRAY_SIZE(settings)
     }
};

API documentation 

Header file: include/bluetooth/mesh/sensor.h

Source file: subsys/bluetooth/mesh/sensor.c

group bt_mesh_sensor

API for Bluetooth Mesh Sensors.

Defines

CONFIG_BT_MESH_SENSOR_CHANNEL_ENCODED_SIZE_MAX

BT_MESH_SENSOR_PERIOD_DIV_MAX: Largest period divisor value allowed.

BT_MESH_SENSOR_INTERVAL_MAX: Largest sensor interval allowed. The value is represented as 2 to the power of N milliseconds.

BT_MESH_SENSOR_CH_STR_LEN: String length for representing a single sensor channel.

BT_MESH_SENSOR_VALUE_IN_RANGE(_value, _start, _end)

Returns whether or not encoded sensor value _value is in the range [_start, _end], inclusive.

Parameters:

_value – [in] The value to check.
_start – [in] Start point of the range to check, inclusive.
_end – [in] End point of the range to check, inclusive.

BT_MESH_SENSOR_TYPE_FLAG_SERIES: Flag indicating this sensor type has a series representation.

BT_MESH_SENSOR_TOLERANCE_ENCODE(_percent)

Encode a sensor tolerance percentage.

Parameters:

_percent – [in] The sensor tolerance to encode, in percent.

Enums

enum bt_mesh_sensor_sampling

Sensor sampling type.

Represents the sampling function used to produce the presented sensor value.

Values:

enumerator BT_MESH_SENSOR_SAMPLING_UNSPECIFIED: The sampling function is unspecified

enumerator BT_MESH_SENSOR_SAMPLING_INSTANTANEOUS: The presented value is an instantaneous sample.

enumerator BT_MESH_SENSOR_SAMPLING_ARITHMETIC_MEAN: The presented value is the arithmetic mean of multiple samples.

enumerator BT_MESH_SENSOR_SAMPLING_RMS: The presented value is the root mean square of multiple samples.

enumerator BT_MESH_SENSOR_SAMPLING_MAXIMUM: The presented value is the maximum of multiple samples.

enumerator BT_MESH_SENSOR_SAMPLING_MINIMUM: The presented value is the minimum of multiple samples.

enumerator BT_MESH_SENSOR_SAMPLING_ACCUMULATED: The presented value is the accumulated moving average value of the samples. The updating frequency of the moving average should be indicated in bt_mesh_descriptor::update_interval. The total measurement period should be indicated in bt_mesh_descriptor::period.

enumerator BT_MESH_SENSOR_SAMPLING_COUNT: The presented value is a count of events in a specific measurement period. bt_mesh_descriptor::period should denote the measurement period, or left to 0 to indicate that the sample is a lifetime value.

enum bt_mesh_sensor_cadence

Sensor sampling cadence

Values:

enumerator BT_MESH_SENSOR_CADENCE_NORMAL: Normal sensor publish interval.

enumerator BT_MESH_SENSOR_CADENCE_FAST: Fast sensor publish interval.

enum bt_mesh_sensor_value_status

Status of conversion from bt_mesh_sensor_value.

Values:

enumerator BT_MESH_SENSOR_VALUE_NUMBER: The encoded sensor value represents a number.

enumerator BT_MESH_SENSOR_VALUE_CONVERSION_ERROR: An error ocurred during conversion from the encoded sensor value.

enumerator BT_MESH_SENSOR_VALUE_CLAMPED: The encoded value could not fit in the target type and was clamped to the closest available value.

enumerator BT_MESH_SENSOR_VALUE_UNKNOWN: The encoded sensor value represents an unknown value.

enumerator BT_MESH_SENSOR_VALUE_INVALID: The encoded sensor value represents an invalid value.

enumerator BT_MESH_SENSOR_VALUE_MAX_OR_GREATER: The encoded sensor value represents a value greater than or equal to the format maximum.

enumerator BT_MESH_SENSOR_VALUE_MIN_OR_LESS: The encoded sensor value represents a value less than or equal to the format minimum.

enumerator BT_MESH_SENSOR_VALUE_TOTAL_DEVICE_LIFE: The encoded sensor value represents the total lifetime of the device.

Functions

int bt_mesh_sensor_value_compare(const struct bt_mesh_sensor_value *a, const struct bt_mesh_sensor_value *b)

Compare two bt_mesh_sensor_value instances.

Parameters:

a – [in] The first value to compare.
b – [in] The second value to compare.

Returns:

0 if a == b, 1 if a > b, -1 otherwise (including if a and b are not comparable).

static inline bool bt_mesh_sensor_value_status_is_numeric(enum bt_mesh_sensor_value_status status)

Returns true if status is a value which can be represented by a number, meaning one of BT_MESH_SENSOR_VALUE_NUMBER, BT_MESH_SENSOR_VALUE_MIN_OR_LESS, BT_MESH_SENSOR_VALUE_MAX_OR_GREATER and BT_MESH_SENSOR_VALUE_CLAMPED.

Parameters:

status – [in] The value to check.

Returns:

true if status is numeric, false otherwise.

enum bt_mesh_sensor_value_status bt_mesh_sensor_value_to_float(const struct bt_mesh_sensor_value *sensor_val, float *val)

Convert a bt_mesh_sensor_value to a float.

If this function returns a status for which bt_mesh_sensor_value_status_is_numeric returns false, val is not modified.

Parameters:

sensor_val – [in] The bt_mesh_sensor_value to convert.
val – [out] The resulting float.

Returns:

The status of the conversion.

int bt_mesh_sensor_value_from_float(const struct bt_mesh_sensor_format *format, float val, struct bt_mesh_sensor_value *sensor_val)

Convert a float to a bt_mesh_sensor_value.

If val has a value that cannot be represented by the format, sensor_val will be set to the value clamped to the range supported by the format, and this function will return -ERANGE. This will clamp to “Greater than or equal to the maximum value” and “Less than or equal to the minimum value” if these are supported by the format.

If this function returns an error code other than -ERANGE, sensor_val is not modified.

Parameters:

format – [in] Format to use when encoding the sensor value.
val – [in] The float to convert.
sensor_val – [out] The resulting bt_mesh_sensor_value.

Returns:

0 on success, (negative) error code otherwise.

enum bt_mesh_sensor_value_status bt_mesh_sensor_value_to_micro(const struct bt_mesh_sensor_value *sensor_val, int64_t *val)

Convert a bt_mesh_sensor_value instance to an integer in micro units.

If this function returns a status for which bt_mesh_sensor_value_status_is_numeric returns false, val is not modified.

Parameters:

sensor_val – [in] The bt_mesh_sensor_value to convert.
val – [out] The resulting integer.

Returns:

The status of the conversion.

int bt_mesh_sensor_value_from_micro(const struct bt_mesh_sensor_format *format, int64_t val, struct bt_mesh_sensor_value *sensor_val)

Convert an integer in micro units to a bt_mesh_sensor_value.

If val has a value that cannot be represented by the format, sensor_val will be set to the value clamped to the range supported by the format, and this function will return -ERANGE. This will clamp to “Greater than or equal to the maximum value” and “Less than or equal to the minimum value” if these are supported by the format.

If this function returns an error code other than -ERANGE, sensor_val is not modified.

Parameters:

format – [in] Format to use when encoding the sensor value.
val – [in] The integer to convert.
sensor_val – [out] The resulting bt_mesh_sensor_value.

Returns:

0 on success, (negative) error code otherwise.

enum bt_mesh_sensor_value_status bt_mesh_sensor_value_to_sensor_value(const struct bt_mesh_sensor_value *sensor_val, struct sensor_value *val)

Convert a bt_mesh_sensor_value instance to a sensor_value (include/zephyr/drivers/sensor.h).

If this function returns a status for which bt_mesh_sensor_value_status_is_numeric returns false, val is not modified.

Parameters:

sensor_val – [in] The bt_mesh_sensor_value to convert.
val – [out] The resulting sensor_value.

Returns:

The status of the conversion.

int bt_mesh_sensor_value_from_sensor_value(const struct bt_mesh_sensor_format *format, const struct sensor_value *val, struct bt_mesh_sensor_value *sensor_val)

Convert a sensor_value (include/zephyr/drivers/sensor.h) instance to a bt_mesh_sensor_value.

If val has a value that cannot be represented by the format, sensor_val will be set to the value clamped to the range supported by the format, and this function will return -ERANGE. This will clamp to “Greater than or equal to the maximum value” and “Less than or equal to the minimum value” if these are supported by the format.

If this function returns an error code other than -ERANGE, sensor_val is not modified.

Parameters:

format – [in] Format to use when encoding the sensor value.
val – [in] The sensor_value to convert.
sensor_val – [out] The resulting bt_mesh_sensor_value.

Returns:

0 on success, (negative) error code otherwise.

enum bt_mesh_sensor_value_status bt_mesh_sensor_value_get_status(const struct bt_mesh_sensor_value *sensor_val)

Return a bt_mesh_sensor_value_status describing the value in a bt_mesh_sensor_value.

Parameters:

sensor_val – [in] The value to return the status for.

Returns:

The status describing the value.

int bt_mesh_sensor_value_from_special_status(const struct bt_mesh_sensor_format *format, enum bt_mesh_sensor_value_status status, struct bt_mesh_sensor_value *sensor_val)

Convert a bt_mesh_sensor_value_status value to a bt_mesh_sensor_value.

This is useful for creating a bt_mesh_sensor_value representing a special status value like BT_MESH_SENSOR_VALUE_UNKNOWN or BT_MESH_SENSOR_VALUE_TOTAL_DEVICE_LIFE.

This cannot be used to create a value representing BT_MESH_SENSOR_VALUE_NUMBER. Use one of bt_mesh_sensor_value_from_sensor_value, bt_mesh_sensor_value_from_micro or bt_mesh_sensor_value_from_float instead.

Not all formats can represent all special status values. In the case where the supplied status value cannot be represented by the format, this function will return a (negative) error code.

Parameters:

format – [in] Format to use when encoding the sensor value.
status – [in] The bt_mesh_sensor_value_status value to convert.
sensor_val – [out] The resulting bt_mesh_sensor_value on success. Unchanged otherwise.

Returns:

0 on success, (negative) error code otherwise.

bool bt_mesh_sensor_value_in_column(const struct bt_mesh_sensor_value *value, const struct bt_mesh_sensor_column *col)

Check whether a single channel sensor value lies within a column.

Parameters:

value – [in] Value to check. Only the first channel is considered.
col – [in] Sensor column.

Returns:

true if the value belongs in the column, false otherwise.

int bt_mesh_sensor_ch_to_str(const struct bt_mesh_sensor_value *ch, char *str, size_t len)

Get a human readable representation of a single sensor channel.

Note

This prints float values internally for most formats, which requires CONFIG_CBPRINTF_FP_SUPPORT to be enabled.

Parameters:

ch – [in] Sensor channel to represent.
str – [out] String buffer to fill. Should be BT_MESH_SENSOR_CH_STR_LEN bytes long.
len – [in] Length of str buffer.

Returns:

Number of bytes that should have been written if str is sufficiently large.

const char *bt_mesh_sensor_ch_str(const struct bt_mesh_sensor_value *ch)

Get a human readable representation of a single sensor channel.

Note

This prints float values internally for most formats, which requires CONFIG_CBPRINTF_FP_SUPPORT to be enabled.

Note

This function is not thread safe.

Parameters:

ch – [in] Sensor channel to represent.

Returns:

A string representing the sensor channel.

const struct bt_mesh_sensor_type *bt_mesh_sensor_type_get(uint16_t id)

Get the sensor type associated with the given Device Property ID.

Only known sensor types from Sensor types will be available. Sensor types can be made known to the sensor module by enabling CONFIG_BT_MESH_SENSOR_ALL_TYPES or by referencing them in the application.

Parameters:

id – [in] A Device Property ID.

Returns:

The associated sensor type, or NULL if the ID is unknown.

const struct bt_mesh_sensor_format *bt_mesh_sensor_column_format_get(const struct bt_mesh_sensor_type *type)

Get the format of the sensor column data.

Parameters:

type – [in] Sensor type.

Returns:

The sensor type’s sensor column format if series access is supported. Otherwise NULL.

struct bt_mesh_sensor_unit

#include <sensor.h>

Unit for single sensor channel values.

Public Members

const char *name: English name of the unit, e.g. “Decibel”.

const char *symbol: Symbol of the unit, e.g. “dB”.

struct bt_mesh_sensor_channel

#include <sensor.h>

Single sensor channel

Public Members

const struct bt_mesh_sensor_format *format: Format for this sensor channel.

struct bt_mesh_sensor_type

#include <sensor.h>

Sensor type. Should only be instantiated in sensor_types.c. See sensor_types.h for a list of all defined sensor types.

Public Members

uint16_t id: Device Property ID.

uint8_t flags

Flags,