Implementation of TYPE_SIGNIFICANT_MOTION sensor in android

Question

In 4.4, Google introduced the Significant Motion Sensor.

Assuming that it is software implemented, using hardware sensors like the accelerometer and gyroscope, I'd like to know how exactly it was done (I couldn't find it in the sources as well).

Answer 1

It really depends on the hardware implementation. For example, the HTC "flounder" (Nexus 8/9) has a HAL which exposes this. Similarly, the Asus "tilapia" and "grouper" (Nexus 7), Samsung "manta" (Nexus 10), and LG "hammerhead" (Nexus 5) utilize the invensense HAL to expose the same. In these cases the data is coming from a kernel driver exposed interface, which could be a real hardware signal. For example, there are 3 axis G-sensors (commonly used for accelerometers) which can detect "shake" or sudden motion and provide a separate interrupt to the application processor. So the bottom line is that the significant motion sensor is not necessarily a software derived sensor.