The sensor manager API manages the sensors that are enabled in an application. The API allows a sensor device to register itself with the sensor manager and an application to look up the sensors that are enabled. The sensor manager maintains a list of sensors, each represented by a struct sensor object defined in the the Sensor API.
When the BSP or the sensor creator package creates a sensor device in the kernel, via the os_dev_create() function, the sensor device init function must initialize a struct sensor object and call the sensor_mgr_register() function to register itself with the sensor manager.
An application uses the sensor manager API to look up the struct sensor object for a sensor. The sensor API and the sensor listener API perform operations on a sensor object. The sensor manager API provides the following sensor lookup functions:
sensor_mgr_find_next_bytype(): This function returns the next sensor, on the sensors list, whose configured sensor types match one of the specified sensor types to search for. The sensor types to search are specified as a bit mask. You can use the function to search for the first sensor that matches or to iterate through the list and search for all sensors that match. If you are iterating through the list to find the next match, you must call the sensor_mgr_lock() function to lock the sensors list before you start the iteration and call the sensor_mgr_unlock() unlock the list when you are done. You do not need to lock the sensor list if you use the function to find the first match because the sensor_mgr_find_next_bytype() locks the sensors list before the search.
sensor_mgr_find_next_bydevname(): This function returns the sensor that matches the specified device name.
Note: There should only be one sensor that matches a specified device name even though the function name suggests that there can be multiple sensors with the same device name.
An application may configure a sensor device to only support a subset of supported sensor types. The sensor_mgr_match_bytype() function allows an application to check whether a sensor is configured for one of the specified sensor types. The type to check is a bit mask and can include multiple types. The function returns a match when there is a match for one, not all, of the specified types in the bit mask.
The sensor manager implements a poller that reads sensor data from sensors at specified poll rates. If an application configures a sensor to be polled, using the sensor_set_poll_rate_ms() function defined in the sensor API, the sensor manager poller will poll and read the configured sensor data from the sensor at the specified interval.
The sensor manager poller uses an OS callout to set up a timer event to poll the sensors, and uses the default OS event queue and the OS main task to process timer events. The SENSOR_MGR_WAKEUP_RATE syscfg setting specifies the default wakeup rate the sensor manager poller wakes up to poll sensors. The sensor manager poller uses the poll rate for a sensor if the sensor is configured for a higher poll rate than the SENSOR_MGR_WAKEUP_RATE setting value.
Note: An application needs to register a sensor listener to receive the sensor data that the sensor manager poller reads from a sensor.
The sensor manager API uses the struct sensor and sensor_type_t types.
These are the functions defined by the sensor manager API. Please see the sensor.h include file for details.
| Function | Description |
|---|---|
| sensor_mgr_find_next_byname | Returns the next sensor from the sensor manager list that matches the specified device name. An application uses this function. You must call the sensor_mgr_lock() function to lock the sensor manager list if you are iterating through the sensor manager list. |
| sensor_mgr_find_next_bytype | Returns the next sensor from the sensor manager list that matches one of the specified sensor types. An application uses this function. You must call the sensor_mgr_lock() function to lock the sensor manager list if you are iterating through the sensor manager list. |
| sensor_mgr_lock | Locks the sensor manager list. An application uses this function. |
| sensor_mgr_match_bytype | Indicates whether a given sensor is configured for one of the specified sensor types. An application uses this function. Note: The function takes a pointer to a variable with the bit mask of the types to match. |
| sensor_mgr_register | Registers a sensor object. A sensor device driver uses this function. |
| sensor_mgr_unlock | Unlocks the sensor manager list. An application uses this function. |