The Arm Cortex-M138+ MCU is not a standalone brand but a microcontroller unit (MCU) based on Arm's Cortex-M processor architecture, developed by Arm Holdings, a UK-based semiconductor and software design company. Arm licenses its Cortex-M cores to various manufacturers globally, who integrate them into their MCUs. The Cortex-M138+ is tailored for embedded systems, serving industries like industrial automation, consumer electronics, automotive, and IoT. It offers high performance, low power consumption, and real-time capabilities, making it ideal for applications such as sensors, motor control, and smart devices. Companies like STMicroelectronics, NXP, and Texas Instruments produce MCUs using Arm Cortex-M cores.