Digital Electronics - Counters

A Detailed study on Digital Counters.

1. BASICS OF ELECTRICAL AND ELECTRONICS ENGINEERING ASSIGNMENT PRESENTATION COUNTERS – DIGITAL ELECTRONICS

2. Content INTRODUCTION BENEFITS OF COUNTERS TYPES OF COUNTERS ASYNCHRONOUS COUNTERS BINARY RIPPLE COUNTER

3. Introduction Counters are a specific type of sequential circuit. Like registers, the state, or the flip-flop values themselves, serves as the “output.” The output value increases by one on each clock cycle. After the largest value, the output “wraps around” back to 0. 00 01 10 11 1 1 1 1

4. Benefits of counters Counters can act as simple clocks to keep track of “time.” You may need to record how many times something has happened. How many bits have been sent or received? How many steps have been performed in some computation? All processors contain a program counter , or PC . The PC increments once on each clock cycle, and the next program instruction is then executed.

5. Asynchronous Counters The flip-flops do not change states at exactly the same time as they do not have a common clock pulse. Output of one flip-flop is connected to the clock input of the next more-significant flip-flop. Its simple and requires less hardware. Has speed limitation. K J K J HIGH Q Q 1 Q FF1 FF0 CLK C C Timing diagram 00  01  10  11  00 ...

6. Binary ripple counter The counter is called ripple counter because the output of one flip-flop feed to the clock input of another The flip flops respond to negative going clock edge. Each flip flop divides the incoming clock pulse frequency by a factor of 2. Cumulative delay is a drawback.

7. 4-Bit Asynchronous Counter

8. Synchronous Counter Synchronous Counters are so called because the clock input of all the individual flip-flops within the counter are all clocked together at the same time by the same clock signal. The clock signal is directly applied to all Flip flops in a parallel sequence.

9. 4-Bit Synchronous Counter

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