ABSTRACT
This chapter considers the most common general-purpose circuit components often found in microcontroller boards. A circuit is said to be bistable if it has two, and only two, stable states. A flip-flop is such a circuit since it performs as a 1-bit memory that stores either the value 0 or 1. A flip-flop is an electronic circuit with two stable states, since its output is either 0 or +5 VDC. In synchronous circuits unconstrained changes in logic gate outputs are not allowed. Instead, the logic is designed so that logic level changes can progress through the circuitry one stage at a time under control of a clock. The use of flip-flops in digital circuits usually requires some way of placing the signals in a known state. Digital devices use the rising or the falling edges of the square wave to run logic circuits.
