MCU Roundup: New Embedded Features for the Edge, IoT, and Automotive

Renesas, Nuvoton, and STMicroelectronics each recently released microcontroller innovations for next-generation smart applications. These offerings provide ultra-low power for human machine interfaces (HMI), improved security at the edge, and a longer guaranteed availability for automotive microcontrollers.

Renesas Introduces Low-Power RL78/L23 MCUs

Renesas has announced the 32 MHz RL78/L23 16-bit microcontroller group with battery life improvements over its predecessors. The RL78/L23 (datasheet linked), operating from 1.6 V to 5.5 V, adds to the low-power RL78 smart device family. Renesas optimized the new MCUs for battery-powered devices that remain in standby the majority of the time, with occasional moments of activity. The minimum standby current is 0.365 μA, and active operating is 109 μA/MHz. It has a 1-μs wakeup time, which keeps active time to a minimum.

The RL78/L23. Image used courtesy of Renesas

The RL78/L23 features a built-in segment LCD controller and capacitive touch interface, improving the LCD performance over earlier family members. The VL4 LCD reference mode consumes 30% less power than the previous MCUs in the family. Further display-related power reduction comes with a snooze mode sequencer (SMS) that allows LCD activity without the CPU. The SMS circuit allows some activity without waking up the CPU. In addition to the LCD controller, the MCU has other key HMI component integration, such as a capacitive touch sensor, a temperature sensor, and an internal oscillator.

The new group offers up to 512 KB of dual-bank flash memory for seamless firmware over-the-air (FOTA) updating and up to 32 KB of SRAM and 8 KB of data flash. An integrated IH timer (KB40) supports up to three-channel induction heating control, with an overall operating temperature range of -40°C to +105°C. The MCUs support multiple serial interfaces, including UART, I2C, and CSI, and include an IEC60730-compliant self-test library. 

The MCU group aims to reduce MCU power draw for HMI devices in the home and industrial markets, such as cooktops and HVAC systems. Renesas also announced the availability of the fast-prototyping board (FPB-RL78L23) along with a capacitive touch evaluation system (RSSK-RL78L23).

Nuvoton Upgrades NuMicro M2354 MCU Security

Nuvoton recently released an upgraded NuMicro M2354 microcontroller with security improvements. Nuvoton calls out applications such as server root of trust (RoT) security, smart city devices, and Internet of Things (IoT) applications. The new device is designed for “long-term confidentiality requirements and highly sensitive data protection scenarios.”

Functional block diagram of the Nuvoton M2354. Image used courtesy of Nuvoton

The microcontroller is powered by an Arm Cortex-M23 core at 96 MHz with Arm TrustZone capabilities. It runs at 89.3 μA/MHz in LDO mode and 39.6 μA/MHz in DC-DC mode, with 2-µA standby power and a deep power-down at 0.1 µA. For memory, the device features FOTA-capable, dual-bank flash memory of up to 1,024 KB and 256 KB of SRAM. It supports CAN, USB 2.0 full-speed OTG, PWM, UART, SPI/I2S, Quad-SPI, I²C, and RTC.

It operates from voltages ranging from 1.7 V to 3.6 V and in temperatures spanning -40°C to +105°C. The MCU comes in packages as small as WLCSP49, with larger available sizes including LQFP-48, LQFP-64, and LQFP-128.

With its focus on security, the NuMicro M2354 includes execute-only memory (XOM), a hardware key store, and a cryptographic hardware accelerator supporting FIPS PUB 197/180/180-2/180-4 and NIST SP 800-38A. The MCU, compliant with PSA Level 3 and SESIP Level 3 security certifications, features a root-of-trust architecture based on DICE, implemented in Mask ROM, supporting ECDSA P-521. 

The enhanced security of the MCU is designed to fend off attacks in all phases of operation, including boot mode, during upgrade, and in-operation attacks. The XOM prevents code theft for reverse engineering protection. The hardware key store protects against side-channel and fault injection attacks, while the RoT architecture ensures a chain of trust during boot with a unique device identity. Such comprehensive security makes the device useful as a RoT add-in to larger systems or as a standalone IoT microcontroller.

Nuvoton offers the NuMaker-M2354KJB evaluation board to assist with development. The board has Arduino UNO-compatible headers and accommodates a wide variety of peripherals.

ST Extends Availability of SPC58 MCUs to 20 Years

STMicroelectronics has announced the 20-year availability of its SPC58 family of automotive MCUs. The announcement assures manufacturers in the automotive industry a guaranteed long-term supply of a key smart-vehicle component. The seven product lines in the SPC58 family will be available until at least 2038–2041. The family had previously been guaranteed available for 15 years from the date of product launch. In addition, they have ensured the availability of the SPC58 H series until 2041. The H series contains up to 10 MB of nonvolatile memory (NVM).

Block diagram of the SPC58 H line MCUs. Image used courtesy of STMicroelectronics (page 10 of the datasheet)

The SPC58 series MCU is widely deployed in the automotive industry for in-auto communications, powertrain, body applications (such as lighting and locking), and security. Two of the seven lines, the high-performance SPC58 E and SPC58 N, are specifically designed for electric powertrain and chassis-safety applications.

ST claims its highest performing models have three e200z4 32-bit Power Architecture cores. It offers 1 MB to 10 MB on-chip NVM and supports a broad number of communication protocols, including an ISO CAN-FD-compliant modular controller area network (MCAN). It also has an IEEE 802.3 10/100 Ethernet controller with IEEE 802.1Q virtual LAN. 

For security, the SPC58 family includes a hardware security module (HSM) with an independent core and memory to isolate security-sensitive processes and data, enabling users to build EVITA-compliant systems. It offers hardware-based functional safety for certification up to ISO 26262 ASIL-B, and devices in the SPC58 E and SPC58 N lines meet ASIL-D safety-integrity level.

With today’s cars routinely lasting more than a decade and 200,000 miles, long-term support is a necessity. Complex systems cannot be redesigned later in life to accommodate obsoleted key components, such as MCUs. STMicroelectronics aims to give developers the confidence needed to use their MCUs in long-life automotive applications.