Nuvoton Technology has launched the NuMicro M3331 series, a new family of 32-bit microcontrollers built on the Arm Cortex-M33 core with TrustZone security technology.

Running at up to 180 MHz with a built-in DSP instruction set and single-precision floating-point unit, the M3331 series targets industrial automation, smart buildings, renewable energy systems, professional lighting, and gaming products that need a combination of processing performance, hardware security, and diverse connectivity in a compact package.

The family is divided into two sub-series: the M3333, which omits USB connectivity, and the M3334, which includes a USB 2.0 High-Speed OTG controller with an on-chip PHY. Both sub-series share the same core architecture and are available across five package options ranging from a 4-by-4 mm QFN33 to a 14 × 14 mm LQFP128, giving designers flexibility to balance pin count against board area from the earliest stages of hardware planning.

The M3331 series operates across a 1.7 V to 3.6 V supply range, enabling operation in battery-powered and energy-harvesting applications alongside conventional mains-powered industrial systems.

Hardware Security from Boot to Runtime

The M3331 series implements Arm TrustZone technology at the hardware level, partitioning the processor into secure and non-secure execution environments. This separation means that cryptographic keys, authentication routines, and firmware update logic can run in an isolated context that application-layer code, and any vulnerabilities it might carry, cannot access.

M3331 MCU series block diagram

Secure Boot with Root of Trust (ROT) ensures that only authorized firmware executes from the moment the MCU powers on. The boot chain is validated in hardware before any code runs, closing the window for firmware tampering attacks that can compromise devices deployed in physically accessible locations like factory floors, building management panels, or outdoor renewable energy installations.

For developers who need to protect proprietary algorithms, the M3331 series includes eXecute-Only Memory (XOM) across four flash regions. Code stored in XOM regions can be executed but not read back, preventing the extraction of core IP even by someone with physical access to the debug interface. The flash memory itself is protected by Error-Correcting Code (ECC) that detects and corrects single-bit errors in real time, a critical requirement in industrial settings where electromagnetic interference or radiation-induced bit flips can corrupt firmware.

Bootloader flexibility is supported through an 8 KB user-defined LDROM (Loader ROM) region that can be reprogrammed to implement custom boot sequences, allowing OEMs to enforce their own firmware validation policies or integrate proprietary initialization routines without modifying the main application flash. Combined with a 96-bit Unique ID and 128-bit Customer ID, these features give OEMs a layered defense against cloning and reverse engineering.

Connectivity and Analog Capabilities

On the communications front, the M3331 series introduces an I3C interface alongside two CAN FD controllers, five UARTs, three I2C buses, three SPI/I2S interfaces, and Quad-SPI. The I3C interface is notable as an emerging standard that offers higher data rates and lower power consumption than I2C while maintaining backward compatibility, making it increasingly relevant for sensor-dense industrial and consumer designs.

The dual CAN FD controllers support the higher data throughput that modern industrial networks demand, particularly in smart factory environments. The M3334 sub-series adds USB 2.0 High-Speed OTG with an integrated PHY and an SDH (Secure Digital Host Controller) interface, addressing applications like gaming peripherals and smart consumer devices that require high-bandwidth storage or low-latency data transfer.

In terms of analog, the M3331 series integrates a 12-bit SAR ADC capable of sampling at 4.2 Msps across up to 16 channels, alongside two analog comparators. Up to 48 PWM output channels provide the control resolution needed for professional and stage lighting applications.

SRAM and Flash

The M3331 series includes 64 KB of SRAM with hardware parity checking on every read and write operation. This runtime data protection detects corruption of the runtime state before it can trigger incorrect outputs or system faults.

Combined with the flash ECC protection, this approach guards against the full spectrum of memory-related failures common in harsh industrial environments where noise immunity directly impacts product reliability and safety.

An Enhanced LED Light Strip Interface (ELLSI) and 10 LED Light Strip Interface (LLSI) units support direct ARGB LED strip control, reducing external component count for gaming peripherals, decorative lighting, and architectural installations. The operating temperature range of -40 C to 105 C and ESD ratings of 4 kV HBM and 4.4 kV EFT position the family for deployment in harsh industrial environments alongside consumer applications.

NuMaker-M3333KI evaluation board

Development support includes the NuMaker-M3333KI (see above) and NuMaker-M3334KI evaluation boards, with software compatibility across FreeRTOS, Zephyr, RT-Thread, emWin, and LVGL.

All images used courtesy of Nuvoton.