Control LCD backlight with motion sensor

[adamwalach]

With sensor like HC-SR501 or similar we could control the LCD backlight. That would make our device more friendly for in-door use. HC-SR501 could be connected to an unused input pin from NodeMCU.
Then, we could add support for it in the code so every time motion is detected the LCD backlight will be turned on (by a command - we do not need to add any additional hardware)

AC:

• LCD backlight is turned on only when motion is detected
• delay (for how long backlight is on) can be set in config (in the same way as WIFI name)