The Arm Cortex-M300+ 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-M300+ series offers high performance, low power consumption, and advanced security features, making them ideal for real-time control and connectivity solutions. Arm Holdings provides the IP (intellectual property) for these MCUs, which are then manufactured by various semiconductor companies worldwide.