Renesas configures MCU family around smart meter standards

November 07, 2016 // By Graham Prophet
Renesas Electronics Europe has added the RL78/I1C Group of microcontrollers supporting meter international standards (DLMS) for smart power meters. The distinguishing features of the MCUs for this task include enhanced security and arithmetic operation performance for DLMS, for a wide range of power meter platforms, from single-phase to three-phase

Renesas developed the RL78/I1C MCUs for smart meters with DLMS (Device Language Message Specification, an IEC standard used by power companies for exchanging meter data) support, employing key features from the current RL78/I1B Group of MCUs. The MCUs are available in seven versions, with on-chip memory capacities ranging from 64 kB for low-end single-phase meters, 128 kB for high-end single-phase meters, and 256 kB for three-phase meters; and package pin counts from 64 pins for space-saving needs, 80 pins for single-phase meters aimed for use in emerging countries, to 100 pins for single-phase meters aimed for use in advanced applications.


The MCUs offer the ability to implement electric power measurement processing and DLMS processing on a single chip; the RL78/I1C integrates an AES (encryption) hardware engine. The RL78/I1C ICs implement the AES GCM mode (Galois/Counter Mode, a cryptographic mode of operation that enables simultaneous encryption and authentication of data) required by the DLMS standard in hardware, thereby delivers a speed boost of 20 times or more compared with encryption and decryption using software processing on existing Renesas MCUs. An on-chip phase-locked loop (PLL) boosts the maximum operating frequency from 24 MHz to 32 MHz, and the 32-bit multiplier/multiply-and-accumulate unit reduces the load imposed by software power calculation with 24-bit data converted by the 24-bit Δ-Σ A/D converter, resulting in an approximate 30% increase in arithmetic operation capacity. This means that a single chip can handle both electric power measurement processing and DLMS processing.


There is support for three-phase, four-wire meters; an event link controller (allows high-speed module activation by directly linking peripheral hardware devices and bypassing the interrupt controller) function and phase adjustment function coordinate the operation of the four-channel 24-bit Δ-Σ A/D converter and three-channel 10-bit SAR A/D converter. This enables current and voltage measurement on seven channels, as required in three-phase, four-wire meters.


Extended features and functionality vs. the existing RL78/I1B to the new MCUs,