Basic sketch & circuit meant for capturing the blink of a led on a home electricity meter.
The solution features a one-way RF communication between the Attiny85 (sender) and an Arduino UNO board (receiver).
As the photodiode (PD) generates a potential difference or changes its electrical resistance when exposed to light, the idea is to put the PD in front of blinking led on the electricity meter. The PD shall be covered so it does not get light from the surroundings.