sequential circuit

Synchronous sequential circuit analysis is divided into the following steps when analyzing a synchronous sequential circuit: Distinguish the components of the sequential circuit. List the equations. Based on the combined parts of the sequential circuit, write the output function expression of the circuit at that time. And determine the trigger input signal The logical expression (excitation function) of the flip-flop is obtained, thereby obtaining the characteristic equation of the flip-flop. The state truth table is written from the equation obtained in the previous step, and the current state of the flip-flop and the external input signal are used as the input signals of the sequential circuit. The state diagram and state table of the sequential circuit are obtained through the state truth table. Through the state table and state diagram of the circuit, the function of the circuit is described. Example 1: Analyze the circuit shown in Figure (1) and make a state transition table and state Replace the diagram and make an output waveform with the input signal 0110111110. 1. List of equations. The excitation equation is: J1=XQ2, K1=X; J2=X, K2=XQ1. The characteristic equation is: Q1n+1=XQ2+XQ1; Q2n+1=XQ2+XQ1Q2 The output equation is: Z=XQ1Q2 2. Column state transition truth table. As shown in Table (2): 3. Draw the state transition diagram. As shown in Figure (3): 4. Function Description. It can be seen from the state transition table that this circuit is a "1111" sequence detection circuit. When this sequence occurs, the output is "1", otherwise it is "0" 5. Draw a timing diagram. First list the timing table, according to The timing table (Figure (4)) makes the timing diagram as shown in Figure (5):