The book discusses in details the main hardware and firmware fundamentals about micro- controllers. The goal is to present all the concepts necessary to understand and design an embedded system based on microcontrollers. The book discusses on: Binary logic and arithmetic, Embedded-systems basics, Low-end 8-bit microcontrollers by Microchip and STMicroelectronics, On-chip memories, Input/Output ports, peripherals, Assembly instruction sets, EasyPIC evaluation board by MikroElektronika, High-end 32-bit cores by ARM-Cortex, STM32F4 microprocessor by STMicroelectronics, Nucleo board for STM32F4 by STMicroelectronics, Custom developed board. The book is not targeted for just either low-end or high-end microcontrollers. Instead, the book fully describes both, moving from the basics of microcontroller systems, to 8-bit devices and then to the 32-bit ones.In fact, the book targets well-renowned, commercially-available microcontrollers by the microelectronic leaders in the field. As for low-end 8-bit microcontrollers, the book reviews the widely-spread and well-assessed devices by Microchip (the PIC16 family) and by STMicroelectronics (the ST6 family). Instead, as for high-end 32-bit microcontrollers, the book presents the leading-edge M3 and M4 cores by ARM-Cortex and its implementation by STMicroelectronics (the STM32F4 series).The Book is very modular and most Chapters can be used as stand-alone mini text books (e.g., Chapter 3 - "8-bit microcontrollers", Chapter 5 - "ARM-Cortex architectures", Chapter 6 - "STM32 microcontroller"). Moreover, Chapter 4 and Chapter 7 provide a very useful insight to electronic circuits employing microcontrollers and on-board components, by means of the EasyPIC v7 board by Mikroelektronika (for PIC microcontrollers) and Nucleo board by STmicroelectronics (for the STM32 ARM-Cortex M4 microcontrollers).