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,