TECHNOLOGY FOR CHANGE

Smart Electricity Meters Now Easier to Design

R. Colin Johnson | Date: 10-07-09 | Comments

Freescale's ColdFire microcontroller instills smarts into electricity meters, enabling consumers and businesses to keep track of electricity usage and its cost.

Smart electricity meters will change the way energy is conserved�by reporting usage wirelessly, by prompting consumers on how much their current usage is costing and by leveling loads on the grid by shifting usage of non-essential appliances, like clothes driers, to off-peak times. However, to realize those smarts�and to make room for next-generation innovations such as wind turbines, solar panels and the recharging of electric vehicles�requires building intelligence into meters.

Enter Freescale Semiconductor. The company described a new ColdFire microcontroller aimed at simplifying the design of such smart meters at the Metering Europe Conference and Exhibition (Oct. 6-8, 2009, Barcelona, booth #660). Freescale's specialized microcontroller for smart meters comes complete with dedicated peripherals, firmware and a turnkey reference design dedicated to the needs of smart electricity meters.

"Today there is a tremendous amount of stimulus money available worldwide to modernize the electricity grids," said John Weil, global product and enablement manager of microcontrollers at Freescale. "To manage these smart energy functions, we've designed a special microcontroller, all the necessary software and even a reference design showing how it can all work together."

Whether the meter is tracking single-phase home usage or industrial usage by three-phase motors, Freescale's new ColdFire microcontroller (MCF51EM) has the capability and software support to instill smarts into electricity meters. The ColdFire microcontroller was designed to lower system cost, power consumption and maintenance costs by including on-chip analog-to-digital converters, programmable delay blocks, an independent real-time clock with calendaring functions, dual secure flash memory banks, an automated meter reading (AMR) interface and drivers for a liquid crystal display (LCD).

The ColdFire microcontroller also benefits from two identical, but completely separate firmware memories. By allowing utility companies to download firmware without disturbing the current operation of the meter, problems with updates can be eliminated. After a download is completed and verified, a special ColdFire instruction quickly swaps the two firmware blocks to realize the new functionality.

Smart meters also need to interface with wireless modems, mostly in the United States, and with power-line-based communications lines, mostly in Europe, prompting Freescale to include a 5-volt interface to external automated meter reading circuits, thus eliminating the need for external components. In addition, Freescale has included LCD drivers for up to 288 segments, and all the software needed to calculate all common energy quantities, such as active-, reactive- and apparent-energy usage.

A special edition of Freescale's CodeWarrior Development Studio for Microcontrollers includes all the development software needed for smart meter applications, along with the real-time operating system (RTOS), the NTFS File System and all the necessary real-time TCP/IP communication routines. Freescale has also prepared a quick-start guide, online training videos, Webcasts, technical documentation and application notes. See it all at here.