To obtain low-power consumption and long battery lifetime, a low-power three-axis accelerometer (U4) has been added to the remote control.
See the schematic below. See also Intelligent power saving.
Figure 1. Accelerometer circuit
The accelerometer has I2C outputs and can detect motion on three axes. The sensitivity is configurable to ±2 g/±4 g/±8 g/±16 g.