Sensor HAL: overview

AN4156

4/12

Doc ID 023584 Rev 1

1

Sensor HAL: overview

The Android sensor HAL is the library which provides the links by kernel-space drivers to the

Android sensor service and Android sensor manager.

The architecture of the Android sensor framework is shown in Figure 1:

●

Application framework: applications that make use of the sensors utilize the

“Application framework” to get data from the devices. The communication starts in the

sensor manager class to then pass to the lower layer through the sensor JNI (Java

native interface).

●

Sensor libraries: these libraries have the purpose of creating a sophisticated interface

for the upper layer. This is done through the sensor manager class, sensor service

class, and the sensor HAL, which is the focus of this document.

●

Kernel: in this layer we find Linux device drivers created using the input subsystem, a

generic Linux framework for all input devices such as the mouse, keyboard, joystick,

etc. The data are exported to the user space through the sysfs virtual file system

(/sys/class/input/). The driver sends/receives data to/from the sensor through

the stable Linux subsystem I2C.

Figure 1.

Android sensor subsystem