The Arm Cortex-M400+ MCU is a series of microcontrollers developed by Arm Holdings, a British semiconductor and software design company. These MCUs are part of the Cortex-M family, designed for embedded applications in industries such as industrial automation, consumer electronics, automotive, and IoT. The Cortex-M400+ series offers high performance, energy efficiency, and advanced features like real-time processing and security, making them ideal for smart devices and industrial control systems. Arm Holdings provides the IP (intellectual property) to manufacturers worldwide, who then produce the actual chips.