Freescale pushes MZ series microcontrollers for smart grid

As the development model of the next generation of power grids, smart grids have received widespread attention around the world. Governments and enterprises around the world have an increasing demand for building smart grids to improve power distribution and save energy. As the world's leading power company, State Grid Corporation of China ("China Grid") has made a new plan for smart grids. With the launch of China Grid's new standards, Freescale Semiconductor has launched a new generation of intelligent microcontrollers (MCUs) MZ series specifically for China Grid applications in response to market demand. This series of MCUs has low cost and price competitiveness, and can achieve flexible solutions. Freescale also provides innovative and convenient reference designs to help developers design the best solutions that meet China Grid's new standards.

The new standard of China State Grid puts forward a series of requirements for the design of single-phase electricity meters, such as: the increase of basic metering functions, complex fee control functions, multiple meter reading communication modes, unified shell molds, and relatively fixed electronic circuit layout and wiring positions. Based on a thorough study of the design requirements of the new standard of China State Grid for single-phase electricity meters, Freescale launched the MZ series MCU and complete electricity meter reference design, which can be said to be tailor-made for China State Grid electricity meters. This series of 8-bit processor chips integrates 60KB, 96KB or 128KB flash memory and provides 64-pin LQFP package. The MZ series microcontroller also provides 32-bit processor chips with integrated 256KB flash memory. All chips in the MZ series can achieve full compatibility with 64-pin chips, and users can upgrade products without modifying PCB wiring. The one-stop reference design provided contains the necessary hardware and software, fully complies with the new standard of China State Grid electricity meters, and can greatly simplify the development of smart meters and speed up product launch.

Freescale's reference design is based on 64K-byte EEPROM with a 2M-byte serial Flash expansion to meet the needs of applications that require enhanced peripherals, improved performance, increased storage capacity and improved system security. In terms of power design, the MCU mainboard and the front-end metering board share a common ground, and the AC power supply and battery power supply are switched through a simple diode path. The AC power supply and battery voltage can be directly sent to the on-chip ADC for power-off detection, eliminating the need for voltage comparators generally designed for power-off detection and battery detection. In terms of real-time clock, the external RTC chip and MCU are controlled through the I2C bus to read the clock parameters, which can realize the frequency calibration of the microcontroller's own internal clock. In the metering part, an external metering chip is used, and the MCU configures the chip and reads data through the SPI bus. The MCU software cooperates to implement software calibration and realize zero-bias calibration of current and voltage. In addition, in terms of data communication, RS485 communication supports a maximum rate of 19200bps, while infrared meter reading communication can support 1200/2400bps. Carrier communication based on the on-chip hardware SCI module can achieve 9600bps serial communication between the MCU and the carrier module. After AC power failure, the MCU enters a low-power sleep mode powered by a battery. Through the internal real-time counter timed wake-up, the power consumption of the entire system can be less than 7uA.

With years of attention and research on the smart grid industry, Freescale has continuously introduced various innovative technologies that can promote the development of the power management industry based on the integration of global R&D forces, and insisted on supporting power management departments with an open vision to cope with the challenges brought by power grid transformation to the industry. The complete solution for the meter reference design launched by Freescale this time is based on the advanced MZ series MCU tailored for the electricity metering market, which can provide developers with a complete plug-and-play solution, which can not only reduce costs and speed up time to market, but also accelerate the construction of an integrated smart grid.