The Arm Cortex-M121+ MCU is a microcontroller unit developed by Arm Holdings, a British semiconductor and software design company. It is part of the Cortex-M series, which is widely used in embedded systems for industrial, automotive, and consumer electronics applications. The Cortex-M121+ MCU is designed for high-performance, low-power applications, offering features like real-time processing, connectivity, and security. Arm's products are licensed to various manufacturers globally, serving industries such as automation, IoT, and smart devices. The company is headquartered in Cambridge, UK, and is a key player in the semiconductor IP market.