An Arduino drives the switch-mode power supply, offering dimming thanks to PWM, and the ability to automatically switch the light on and off using an RTC chip with a battery backup.

In this case i starts at 255 and is decremented to 0; this will dim the light. Play around with the code by using different starting and end values for i.

We know that measuring the speed of light with an Arduino is possible. It’s just that the implementation is hard. Last month we saw [Udo]’s blinkenlight shield that can be used as a lin… ...