1 Related to the time factor (CP)

2 Components containing memory (triggers)

Output equation: the logical expression of each output signal of the sequential circuit

Driving equation: the logical expression of the synchronous input signal of each flip-flop

Equation of state:

counter

register

Shift Register

read/write memory

sequential pulse generator

Synchronous sequential circuit: flip-flops share a clock CP, and the flip-flops whose status is to be updated flip at the same time

Asynchronous sequential circuit: all flip-flops in the circuit do not share a clock CP

Moore type:

Mealy type:

Valid state: In a sequential circuit, any state that is utilized is called a valid state.

Invalid state: In sequential circuits, any unused state is called an invalid state.

Effective loop: In sequential circuits, any loop formed by a valid state is called an effective loop.

Invalid loop: If the invalid state forms a loop, then this kind of loop is called an invalid loop.

Self-starting: In a sequential circuit, although there are invalid states, they do not form a cycle. Such a sequential circuit is called a self-starting sequential circuit.

Cannot self-start: In a sequential circuit, there are invalid states and a cycle is formed between them. Such a sequential circuit is called a sequential circuit that cannot self-start.

1 Carry out logical abstraction and establish original state diagram

2. Simplify the state and find the simplest state diagram.

3 Encode in binary and draw the encoded state diagram

4 Select the flip-flop type and find the clock equation, output equation, state equation and driving equation

5 Draw a logic diagram

6 Check whether the designed circuit can start automatically

① Generally Moore type sequential circuit

②The main component is a clock flip-flop

Classification by number system

Sort by counting method

Classification by clock control

Classification by switching components

The number of effective states of the circuit M: the number of input pulses that the counter can remember

3-bit binary synchronous adding counter

3-bit binary synchronous down counter

Integrated binary synchronous adding counter

3-bit binary asynchronous adding counter

Integrated binary asynchronous counter

Decimal synchronous adding counter

Decimal synchronous down counter

Integrated decimal synchronous adding counter

Integrated decimal asynchronous counter: 74LS290

The main steps

Application example: P289 Example 6.2.1

The main steps

Application example: P290 Example 6.2.2

Integrated counters are generally equipped with input terminals and output terminals for cascading. As long as they are connected correctly, a counter with a larger capacity can be obtained.