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Barometer object implementation for LwM2M client using Wakaama. More...

Detailed Description

Barometer object implementation for LwM2M client using Wakaama.

Warning
This feature is experimental!
This implements the LwM2M Barometer object (ID 3315) as specified in the LwM2M registry. This IPSO object should be used with an air pressure sensor to report a barometer measurement. It also provides resources for minimum/maximum measured values and the minimum/maximum range that can be measured by the barometer sensor. An example measurement unit is pascals.

The sensor value can be updated by the application using the lwm2m_object_barometer_update_value function, or polled when required if a callback is registered upon object instantiation via lwm2m_obj_barometer_args_t::read_cb.

To use this object add USEMODULE += wakaama_objects_barometer to the application Makefile.

Resources

For an XML description of the object see https://raw.githubusercontent.com/OpenMobileAlliance/lwm2m-registry/prod/version_history/3315-1_0.xml

This object is based on the IPSO Sensor base object, therefore it shares the same resources.

Usage

  1. Initialize the LwM2M object with an initialized client pointer.
lwm2m_object_t *obj = lwm2m_object_barometer_init(&client_data);
lwm2m_object_t * lwm2m_object_barometer_init(lwm2m_client_data_t *client_data)
Initialize the Barometer object handle.
  1. Create a new instance of the object with a given configuration (lwm2m_obj_barometer_args_t). Here, you can decide the way of updating the sensor values: polling or pushing. In this case, we register a callback function that is called whenever the sensor value is read.
// callback function to read the sensor value
int _read_cb(void *arg, int16_t *value)
{
(void)arg;
// generate new value
*value = 100;
return 0;
}
// initialize an instance of barometer sensor object
const lwm2m_obj_barometer_args_t barometer_args = {
.max_range_value = 2000.0,
.units = "hPa",
.units_len = sizeof("hPa") - 1,
.instance_id = 0,
.read_cb = _read_cb,
.read_cb_arg = NULL
};
int32_t res = lwm2m_object_barometer_instance_create(&barometer_args);
if (res < 0) {
puts("Could not create barometer object instance");
}
int32_t lwm2m_object_barometer_instance_create(const lwm2m_obj_barometer_args_t *args)
Create a new Barometer instance.
Arguments for the creation of an object based on the IPSO Sensor Base object instance.
int16_t min_range_value
Minimum value that can be measured by the sensor.
  1. You can now update the sensor values using the lwm2m_object_barometer_update_value function.
uint16_t instance_id = (uint16_t)res;
lwm2m_object_barometer_update_value(&client_data, instance_id, new_value);
void lwm2m_object_barometer_update_value(const lwm2m_client_data_t *client_data, uint16_t instance_id, int16_t value)
Update the value of the barometer sensor and trigger a notification to the observing servers,...

Modules

 LwM2M Barometer object compile configurations
 

Files

file  barometer.h
 

Macros

#define LWM2M_BAROMETER_OBJECT_ID   3315
 LwM2M Barometer object ID.
 

Typedefs

typedef lwm2m_obj_ipso_base_sensor_args_t lwm2m_obj_barometer_args_t
 Arguments for the creation of a Barometer object instance.
 

Functions

lwm2m_object_t * lwm2m_object_barometer_init (lwm2m_client_data_t *client_data)
 Initialize the Barometer object handle.
 
int32_t lwm2m_object_barometer_instance_create (const lwm2m_obj_barometer_args_t *args)
 Create a new Barometer instance.
 
void lwm2m_object_barometer_update_value (const lwm2m_client_data_t *client_data, uint16_t instance_id, int16_t value)
 Update the value of the barometer sensor and trigger a notification to the observing servers, if any.
 

Macro Definition Documentation

◆ LWM2M_BAROMETER_OBJECT_ID

#define LWM2M_BAROMETER_OBJECT_ID   3315

LwM2M Barometer object ID.

Definition at line 118 of file barometer.h.

Typedef Documentation

◆ lwm2m_obj_barometer_args_t

Arguments for the creation of a Barometer object instance.

Definition at line 123 of file barometer.h.

Function Documentation

◆ lwm2m_object_barometer_init()

lwm2m_object_t * lwm2m_object_barometer_init ( lwm2m_client_data_t client_data)

Initialize the Barometer object handle.

Parameters
[in]client_dataPointer to the LwM2M client data.
Returns
Pointer to the global handle of the Barometer object.

◆ lwm2m_object_barometer_instance_create()

int32_t lwm2m_object_barometer_instance_create ( const lwm2m_obj_barometer_args_t args)

Create a new Barometer instance.

Parameters
[in]argsInitialize structure with the parameter for the instance. Must not be NULL.
Returns
> 0 value representing the instance ID if the instance was created successfully.
<0 otherwise

◆ lwm2m_object_barometer_update_value()

void lwm2m_object_barometer_update_value ( const lwm2m_client_data_t client_data,
uint16_t  instance_id,
int16_t  value 
)

Update the value of the barometer sensor and trigger a notification to the observing servers, if any.

Parameters
[in]client_dataPointer to the LwM2M client.
[in]instance_idID of the instance to update.
[in]valueNew value for the sensor.