Current

Current Sensor object implementation for LwM2M client using Wakaama. More...

Detailed Description

Current Sensor object implementation for LwM2M client using Wakaama.

Warning

This feature is experimental!
This implements the LwM2M Current Sensor object (ID 3301) as specified in the LwM2M registry.

The sensor value can be updated by the application using the lwm2m_object_current_update_value function, or polled when required if a callback is registered upon object instantiation via lwm2m_obj_current_args_t::read_cb.

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

Resources

For an XML description of the object see https://raw.githubusercontent.com/OpenMobileAlliance/lwm2m-registry/prod/version_history/3317-1_0.xml

This object is based on the IPSO Sensor base object, therefore it shares the same resources. Note that the optional resources "Current Calibration" (ID 5821) and "Application Type" (ID 5750) are not implemented.

Usage

1. Initialize the LwM2M object with an initialized client pointer.

lwm2m_object_t *obj = lwm2m_object_current_init(&client_data);

1. Create a new instance of the object with a given configuration (lwm2m_obj_current_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 current sensor object
const lwm2m_obj_current_args_t current_args = {
    .min_range_value = 0.0,
    .max_range_value = 2000.0,
    .units = "mA",
    .units_len = sizeof("mA") - 1,
    .instance_id = 0,
    .read_cb = _read_cb,
    .read_cb_arg = NULL
};
 
int32_t res = lwm2m_object_current_instance_create(&current_args);
 
if (res < 0) {
    puts("Could not create current object instance");
}

1. You can now update the sensor values using the lwm2m_object_current_update_value function.

uint16_t instance_id = (uint16_t)res;
lwm2m_object_current_update_value(&client_data, instance_id, new_value);

Modules
	LwM2M Current Sensor object compile configurations

Files
file	current.h

Macros
#define	LWM2M_CURRENT_OBJECT_ID   3317
	LwM2M Current Sensor object ID.

Typedefs
typedef lwm2m_obj_ipso_base_sensor_args_t	lwm2m_obj_current_args_t
	Arguments for the creation of a Current Sensor object instance.

Functions
lwm2m_object_t *	lwm2m_object_current_init (lwm2m_client_data_t *client_data)
	Initialize the Current Sensor object handle.
int32_t	lwm2m_object_current_instance_create (const lwm2m_obj_current_args_t *args)
	Create a new Current Sensor instance.
void	lwm2m_object_current_update_value (const lwm2m_client_data_t *client_data, uint16_t instance_id, int16_t value)
	Update the value of the current sensor and trigger a notification to the observing servers, if any.

Macro Definition Documentation

LWM2M_CURRENT_OBJECT_ID

#define LWM2M_CURRENT_OBJECT_ID   3317

LwM2M Current Sensor object ID.

Definition at line 116 of file current.h.

Typedef Documentation

lwm2m_obj_current_args_t

typedef lwm2m_obj_ipso_base_sensor_args_t lwm2m_obj_current_args_t

Arguments for the creation of a Current Sensor object instance.

Definition at line 121 of file current.h.

Function Documentation

lwm2m_object_current_init()

lwm2m_object_t * lwm2m_object_current_init

(

lwm2m_client_data_t *

client_data

)

Initialize the Current Sensor object handle.

Parameters

[in]

client_data

Pointer to the LwM2M client data.

Returns

Pointer to the global handle of the Current Sensor object.

lwm2m_object_current_instance_create()

int32_t lwm2m_object_current_instance_create

(

const lwm2m_obj_current_args_t *

args

)

Create a new Current Sensor instance.

Parameters

[in]

args

Initialize 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_current_update_value()

void lwm2m_object_current_update_value	(	const lwm2m_client_data_t *	client_data,
		uint16_t	instance_id,
		int16_t	value
	)

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

Parameters

[in]	client_data	Pointer to the LwM2M client.
[in]	instance_id	ID of the instance to update.
[in]	value	New value for the sensor.