Android - mandatory sensors?

Question

Is there a mandatory list for hardware on Android devices (e.g. magnetic field, distance)?

If not, which one are common?

Answer 1

These things are defined in the Android Compatibility Definition Document (CDD).

Here is the current one. Check out the hardware-sensors section [7.3.].
As far as I can see all sensors are optional.

Most devices are equipped with the following sensors:

• GPS
• Accelerometer
• Proximity sensor
• Magnetic field
• Light
• Gravity

(from an API viewpoint, some might be the same on a hardware basis)