1. plant grow light controller:
Use an Arduino to control a set of LED grow lights to automatically adjust the light intensity according to different times of the day, mimicking the natural photoperiod and helping indoor plants grow.
2. Holiday countdown device:
Make a device that shows how many days are left until a specific holiday. It displays numbers and can play a holiday song or display a special message on the day of the holiday.
3. smart night light:
Create a nightlight that automatically turns on or off using a photoresistor. The nightlight will automatically turn on when the environment becomes dark and turn off when the environment becomes bright. Color LEDs can be further added to display different colors depending on the time of day or weather.