ARM Microcontroller based watt-hour meter implementation from STMicroelectronics. Link here (PDF)
This document describes, in detail, the hardware and software implementation of a watthour meter using the STM32F101 microcontroller. This cost effective watt-hour meter uses shunt with an operational amplifier as a current sensor, an embedded 12-bit ADC for current and voltage measurement, GPIO for LCD management, and a lot of other peripherals for communication, tamper detection, keyboard, and power disconnection. Powerful architecture of the STM32™ microcontroller allows sampling at 1 Msps. The high sampling rate makes it possible to use methods for ADC resolution enhancement.