Now in its 2nd edition, this textbook has been updated on a new development board from STMicroelectronics - the Arm Cortex-M0+ based Nucleo-F091RC. Designed to be used in a one- or two-semester introductory course on embedded systems, the textbook covers fundamental topics including the CPU, interrupt systems, peripherals, serial communication and multi-tasking. Software examples in this textbook are written in C and the free version of Arm's Keil MDK-ARM integrated development environment is used throughout the materials.