Freescale Kinetis M series microcontrollers redefine smart meter design



Freescale Semiconductor will soon begin shipping Kinetis M series microcontrollers (MCUs) in volume quantities. Based on the 32-bit ARM® CortexTM-M0+ core, Kinetis M series products are designed for next-generation smart meter applications. The cost-effective Kinetis M series MCUs combine a sophisticated analogue front end (AFE), hardware tamper detection and low-power operation to enable the design of secure, high-accuracy 1-, 2- and 3-phase electricity metering solutions. Freescale also provides proven 1-, 2-, and 3-phase hardware reference designs with complex metrology firmware satisfying 0.1% measurement accuracy and all ESD requirements. Traditional smart metering designs typically employ two chips to separate user billing software from the main application code, as required by WELMEC, OIML and other global standards. However, Kinetis M series MCUs handle this task with a single chip due to their on-chip memory protection unit, peripheral bridge, protected GPIO and DMA controller. To guard against external tampering, M series MCUs include active and passive tamper pins with automatic time stamping throughout, including on the independent real-time clock (iRTC). In addition, a random number generator enables faster, easier implementation of encryption algorithms than software implementations. Fundamental to the Kinetis M series design is the analogue front end, delivering exceptional performance and value for smart metering applications. The AFE also allows the M series to address many precision industrial measurement applications other than metering. The AFE consists of: Up to four, non-multiplexed 24-bit Sigma-Delta analogue-to-digital (ADC) converters for simultaneous voltage and current measurement, Two low-noise programmable gain amplifiers providing a dynamic range of 2000 to 1 Up to 12 16-bit SAR ADC inputs for accurate measurement of phase voltage in 3-phase applications A precision voltage reference with low drift over temperature A phase shift compensator to simplify accurate power computation. These features allow the CPU to achieve power calculations with 0.1% accuracy while delivering a high signal-to-noise ratio of 94dB - in line with the latest regulatory standards for such systems. In addition, on-chip analog comparators enable very accurate frequency detection - a key requirement for meters that utilize Fast Fourier Transform (FFT) algorithms. Other key features of Kinetis M series MCUs include: 50 MHz 32-bit ARM Cortex-M0+ core with fast GPIO, 32x32 MAC and excellent code density and energy efficiency 64KB or 128 KB of flash memory with 16 KB SRAM Flexible, segment LCD controller with low-power mode operation and segment fault detect capability (segment LCD module offered only in the 64 & 100 LQFP packages) Multiple low-power modes and fast wake-up options including low-power boot mode Dedicated PLL for 24-bit ADC clock - allows use of low-frequency crystals lowering jitter and maximising AFE performance 1.71-3.6V (no AFE), and 2.7-3.6V (no AFE) 64, 100 LQFP, and 44LGA (5 x 5 mm2) packages Development support Kinetis M series devices are supported by a broad selection of easy-to-use 32-bit tools including the Tower System TWR-KM34Z-50Mdevelopment platform, CodeWarrior Development Studio with integrated Processor Expert auto code generator, MQXTM Lite RTOS, and pre-certified 1-, 2- and 3-phase reference designs for different geographic regions with optional tamper support. Freescale also provides a range of advanced filter and FFT-based metering algorithms free of charge, enabling customers to reduce development costs and time to market. Availability and pricing Production-qualified Kinetis KM34 MCUs with 128 KB of flash memory; four 24-bit ADCs and a low-power segment LCD controller in 100LQFP and 64LQFP packages are planned for availability in November 2013 from Freescale and its distribution partners. Suggested resale pricing starts at $2.01 (USD) for the 64LQFP variants in 10,000-unit quantities. Additional KM1x family members in a small footprint 5x5 mm 44LGA package will enter production in the first quarter of 2014 priced from $1.63 (USD) for 10,000-unit quantities. Freescale at European Utility Week Freescale will exhibit in booth 5F45b at European Utility Week, demonstrating a variety of smart metering solutions based on the Kinetis KM3x for metrology, a sub-GHz wireless MCU and the Kinetis KW20 wireless MCU with integrated ZigBee® support.