From the paper: The registered energy of the static meters was measured using an Arduino microprocessor and optical sensors for detecting the pulses from the L

From the paper: The registered energy of the static meters was measured using an Arduino microprocessor and optical sensors for detecting the pulses from the LED on the static meter fronts. The readings were verified using the liquid crystal display (LCD) reading on the meter. For example, the LCD displayed 18 kWh, and the Arduino measured 17902 Wh, while on another meter the display showed 7.43 kWh, and the Arduino measured 7430 Wh. A conventional electromechanical meter based on the Ferraris principle was used as reference, because consumers are also using this as reference.