Book excerpt: Billions of microcontrollers are sold each year to create embedded systems for a wide range of products. An embedded system is an application-specific computer system which is built into a larger system or device. Using a computer system offers many benefits such as sophisticated control, precise timing, low unit cost, low development cost, high flexibility, small size, and low weight. These basic characteristics can be used to improve the overall system or device in various ways: Improved performance More functions and features Reduced cost Increased dependabilityThis book uses the Renesas RX62N family of processors to demonstrate concepts with hands-on examples complete with source code targeting the YRDKRX62N evaluation board. The 32-bit RX processor core provides remarkable instruction throughput, with high clock rates and hardware support for floating-point and digital-signal processing instructions. The core is also quite agile, responding to fast interrupts in 5 clock cycles. These processors offer a wide range of sophisticated peripherals to simplify interfacing with and controlling external devices.