The sensor class extension supports the linkage between a sensor driver and the Sensor API.
Sensor applications would retrieve the ADXL345 data fields by registering to receive event notifications from the driver. Once an application registers for data-update events, the driver raises these events each time it receives data from the sensor. The frequency of these event notifications correspond to the current report-interval property.
When the driver invokes the ISensorClassExtension::PostEvent method from within the CSensorDdi::PostDataEvent method, the class extension forwards the notification to the Sensor API. The sample driver supports an eventing thread. The code associated with this thread receives data updates from the sensor and ensures that the driver is posting data at the specified report interval. This code invokes the CSensorDdi::ReportIntervalExpired method which, in turn, invokes the PostDataEvent method.