Embedded Lab

Electro-Labs new tutorial project is a PIC microcontroller-based digital power meter that will let you measure the power consumption of an electrical appliance connected to the 230V/50Hz mains line. The project implements a resistor-divider network to scale down the mains voltage and then uses MCP3202 ADC chip to convert the scaled AC voltage to digital counts. For current measurement, the ACS712-30A hall-effect sensor is used in conjunction with another MCP3202 chip. The digital outputs from the ADC chips are then read by the PIC18F252 microcontroller for computing the power. The measured AC RMS voltage, current, and Watts are then displayed on the dot matrix LCD. The beauty of this project is the meter itself is powered from the mains, thus avoiding the need for an external power source.