Characteristics:
1) Solar panel charge battery, which will supply power to the display after full
battery. It will alter to onetime-battery if solar panel is weak.
2) While in reverse gear, the screen will automatically by the signal send it by
the control box and the system start to work automatically and display the distance
with the nearest obstacle
3) While not in gear, the display sleeps automatically and wakes CPU every 2 seconds
to detect whether there is reversing signal
