ABSTRACT
This chapter provides a basic background in digital electronics and in the electronic circuits that are often used in microcontroller-based systems. It explores information on some of the simpler electronic devices often found in electronic circuit boards, such as diodes, Light-Emitting Diode (LED), and logic gates. Digital circuits are the basic building blocks from which microprocessors, microcontrollers, computer systems, and virtually all digital electronic devices are constructed. The LED is a semiconductor device that emits incoherent light when forward-biased. LEDs are used in many electronic devices to signal the presence of an electric current. The bipolar transistor was the first type of transistor to be commercially mass-produced. A bipolar transistor consists of two diodes connected back to back so that they share a common end. One of the most valuable features of the MOS transistors is that they require very small currents to turn on. This makes the MOS transistors behave like voltage-controlled switches in a digital circuit.
