The Arm Cortex-M399+ MCU is a microcontroller unit developed by Arm Holdings, a British semiconductor and software design company. Arm's Cortex-M series is widely used in embedded systems, serving industries such as industrial automation, automotive, consumer electronics, and IoT. The Cortex-M399+ is designed for high-performance real-time applications, offering advanced features like low power consumption, enhanced security, and robust processing capabilities. It is commonly integrated into products like sensors, motor controls, and smart devices. Arm licenses its designs to various manufacturers, enabling a broad ecosystem of compatible hardware and software solutions.