The battlefield for AI microcontrollers is becoming increasingly competitive, and Nuvoton has joined the fray.The NuMicro M55M1 is a low-power AI MCU that combines a 220 MHz Arm Cortex-M55 CPU with a 111 GOPS Ethos-U55 NPU, designed to perform basic AI tasks on-device. It is specifically targeted at small IoT and embedded devices that require low-power voice, audio, or simple image processing.The chip features 1.5 MB of memory, 2 MB of flash storage, and supports external OctoSPI/HyperRAM memory. Connectivity options include Ethernet, USB-OTG, CAN-FD, I3C/I2C/SPI, SDIO, an 8-bit camera interface, as well as ADC, DAC, comparators, PWM, and various low-power modes. It is designed for secure IoT applications, featuring Arm TrustZone, secure boot, AES, and PSA Level 2 certification. Typical applications include voice triggers, smart sensors, simple visual nodes, small appliances, and industrial monitoring devices.
Nuvoton NuMicro M55M1 Specifications:
- CPU– 220 MHz Arm Cortex-M55
- Helium M-Profile Vector Extension (MVE)
- Arm TrustZone Technology
- DSP Extensions
- Hardware Floating Point Unit (FPU), Double Precision
- Architecture – Armv8.1-M
- Cache – 16KB Instruction Cache and 16KB Data Cache
- NPU – Arm Ethos-U55 Micro NPU, 220 MHz, 256 MAC, 110 GOPS processing speed, supporting 8-bit and 16-bit integer operations
- Memory – 1552 KB (1.55MB) total on-chip RAM,
- 1344 KB SRAM (Bank 0: 512KB, Bank 1: 512KB, Bank 2: 320KB)
- 8KB SRAM (Group 3)
- 8KB SRAM in Low Power (LP) domain
- 64KB I-TCM and 128KB D-TCM
- Supports SPI/HyperBus interface (SPIM) for external memory.
- Storage
- 2 Secure Digital Host Controllers (SDHC/SDIO)
- 2MB (2048 KB) on-chip dual storage APROM, supporting OTA upgrades
- 8KB on-chip bootloader ROM (LDROM)
- 3KB One-Time Programmable ROM
- Camera Interface – 8-bit Camera Capture Interface (CCAP)
- Networking – 10/100Mbps Ethernet MAC with RMII interface
- USB
- USB 2.0 High-Speed OTG with on-chip transceiver and Power Delivery (PD)
- Chip-level transceiver supporting USB 2.0 Full-Speed OTG
- Audio
- 4-channel Digital Microphone Input (DMIC) with Voice Activity Detection (VAD) capability
- 2 I2S (Independent)
- Other Peripherals
- 1 12-bit ADC, 5 Msps SAR EADC (up to 24 channels)
- 1 12-bit LPADC, 2 Msps Low Power SAR LPADC (up to 24 channels)
- 2 12-bit DACs, 1 Msps DAC
- 4 Analog Comparators (ACMP)
- 10 UARTs
- 2 CAN FD Controllers
- 4 I2C Interfaces, 1 I3C Interface
- 4 SPI/I2S Interfaces
- 2x QSPI
- 3x Smart Card (ISO-7816-3)
- Universal Serial Control Interface (USCI)
- 8-channel Programmable Serial I/O (PSIO)
- 1 LPUART Interface, 1 LPSPI Interface, 1 LPI2C (Low Power Serial) Interface
- Supports up to 24 channels of PWM (composed of 2 12-channel EPWM and 2 12-channel BPWM)
- Timers – A total of 4 32-bit timers, including
- 2 32-bit Low Power Timers (LPTMR)
- 2x Tick Timers (TTMR)
- Others
- 4 Enhanced Quadrature Encoder Interfaces (EQEI) for motor control
- 4 Enhanced Input Capture (ECAP)
- 2 Watchdog Timers (WDT)
- 2 Window Watchdog Timers (WWDT)
- Real-Time Clock (RTC) with independent VBAT power domain
- 8×6 Keypad Interface (KPI)
- Power – 1.71V to 3.6V
- Package
- LQFP176 (24x24mm)
- LQFP128 (14x14mm)
- LQFP64 (10x10mm)
- Temperature Range – -40°C to +105°C
In terms of software support, the M55M1 series supports Keil MDK, IAR EWARM, and GCC through NuEclipse or VSCode. Nuvoton provides tools such as NuTool PinConfigure, Pin-View, ClockConfig, and NuConsole for pin configuration, clock setup, and debugging. The MCU supports FreeRTOS, Zephyr, and RT-Thread, and can utilize MCU graphics libraries such as emWin, LVGL, and Qt.
Nuvoton offers the NuMaker-X-M55M1D development board based on the NuMicro M55M1 microcontroller. This board provides full pin expansion, Arduino UNO compatible interfaces, mikroBUS interface, HyperRAM, Ethernet PHY, CAN FD, Wi-Fi module, audio codec, MEMS microphone, MPU6500 sensor, dual USB (FS/HS), and microSD card slot. Power options include 5V/3.3V input and a current meter connector for real-time current measurement. The detachable Nu-Link2-Me debugger provides software programming, online/offline programming, and VCOM. It also supports additional modules such as a 5-inch capacitive touch TFT display and a 720p CMOS camera, enabling developers to quickly test human-machine interfaces, AI, sensing, and connectivity features.MCUs based on Cortex-M55, such as Ambiq’s Apollo330 Plus, Alif’s Ensemble series, and Renesas’s RA8M1 series, are designed for similar device-side AI workloads, suitable for low-power, high-performance embedded applications. Like the NuMicro M55M1, these chips also support DSP/ML capabilities through Helium extensions, optional AI accelerators, or wireless connectivity, designed for sensor hubs, IoT nodes, voice interfaces, and human-machine interaction workloads.The M55M1 series includes M55M1R2LJAE (64 pins), M55M1K2LJAE (128 pins), and M55M1H2LJAE (176 pins), which are listed on Mouser but currently not in stock, with a lead time of 30 weeks. The smaller package is priced around $8.50 to $9.80, while the 176-pin model is approximately $17. The NuMaker-X-M55M1D development board is priced at $212 by Nuvoton, which is relatively high.