Nuvaton's NuMicro M254, M256, and M258 series 32-bit low-power microcontrollers (MCUs) are based on an Arm Cortex-M23 core using Armv8-M architecture with COM/SEG LCD driver and capacitive touch key functions. A USB 2.0 full-speed device is equipped to support communication with PC/mobile accessories. It runs up to 48 MHz and features up to 256 Kbytes Flash, up to 32 K bytes SRAM, 1.75 V to 5.5 V wide operating voltage, 5 V I/O tolerance, and -40°C to +105°C operating temperature.

The M254, M256, and M258 series provide low power consumption in the normal run mode of 110 μA/MHz at 48 MHz, power-down mode with 3.8 μA while RTC on and RAM retention with down to 2.2 μA while RTC off; deep power-down mode is down to 1.6 μA. These series integrate RTC with an independent VBAT voltage source pin to support low power mode with main power off and VBAT only.

An 8 x 44, 6 x 46, and 4 x 48 COM/SEG LCD is available on the M254, M256, and M258 series. The COM/SEG LCD driver has selectable bias voltage and duty and a built-in charge pump to support 3 V to 5 V wide voltage of the LCD panel. The M254, M256, and M258 support a capacitive touch sensing function with up to 24 touch keys with single-scan or programmable periodic key scans. The M258 series supports a crystal-less USB 2.0 full-speed device, complying with USB battery charging detection v1.2 (BC 1.2) profile for high-speed battery charging.

The M254, M256, and M258 series are equipped with many peripherals, including timers, watchdog timers, RTCs, up to eight channels of PDMA, four sets of UART, two sets of universal serial control interface (USCI), SPI/I²S, and I²C, one set of ISO-7816-3, and up to 12 channels of basic PWM, making it highly suitable for connecting comprehensive external modules. The series also integrate high-performance analog circuits, such as 16 channels of 12-bit 730 kSPS ADC, up to 2 sets of 12-bit 1 MSPS DAC, and a temperature sensor to reduce external components.

Supported packages include LQFP44, LQFP64, LQFP80, and LQFP128, which are pin-compatible with M251, M252, M031, and M480 series to make easy system design and parts change on functional enhancement.