# 8.4 Counters NextReturn Any clocked sequential circuit whose state diagram contains a single cycle is called a counter. The number of states in the cycle.

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8.4 Counters NextReturn Any clocked sequential circuit whose state diagram contains a single cycle is called a counter. The number of states in the cycle is called the modulus of a counter. A counter with m states is called a modulo- m counter or, sometimes, a divided-by- m counter. An n -bit binary counter has n flip-flops and 2 n states. Each of these states is encoded as the corresponding n -bit binary integer.

(P695 Figure 8-28,8-29). 8.4 Counters 8.4.1 Ripple Counters NextBackReturn Simulation 8.4.2 Synchronous Counters

74x163 is fully synchronous, its outputs change only on the rising edge of CLK. Some applications need an asynchronous clear function as provided by 74x161. The ‘161 has the same pinout as the ‘163. 8.4 Counters 8.4.3 MSI Counters and Applications NextBackReturn CLRLDENTENP Q D Q C Q B Q A RCO 0xxx0 0 0 0 0 10xxD C B A *1 110x hold *1 1110 1111 count *1 Simulation

8.4 Counters NextBackReturn Simulation(160) The 74x160 and 74x162 have the same pinout as the ‘163 and general function as the ‘163 and ‘161, except that the counting sequence is modified to go to state 0 after 9. In other words, these are modulo-10 counters, sometimes called decade counters. Simulation(162)  Applications 1. Using the 74x163 as a modulo-11 counter.

8.4 Counters NextBackReturn Simulation Setting Method

8.4 Counters Resetting Method Simulation NextBackReturn

8.4 Counters NextBackReturn 2. Using the 74x163 as an excess-3 decimal counter. Simulation

(P703~705). 8.4 Counters BackReturn 3. Cascading connections for 74x163-based counters. Simulation 4 *. Decoding Binary-Counter States.

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