6 Counters

Question 1

Sequential counter implementation?

Answer 1

Question 2

The Ring counter?

Answer 2

• Ring counter is a circular shift register with only one flip-flop set at any particular time, all other flip-flops are cleared.
• The bit is shifted from flip-flop to next to produce the sequence of timing signals. The bits are shifted to the right or to the left with every pulse clock, and the last bit is sent back to the first flip-flop.
• The initial value of one bit is preset to 1 and so the counter circulates a 1.

Question 3

Ring Counter design overview?

Answer 3

Question 4

Advantages of a ring counter?

Answer 4

• Ring counters are simpler than a binary counter which requires an adder.
• Their simplicity Advantages them very fast

Question 5

Ring counter applications?

Answer 5

• Ring counters are much used to enable and control a set of devices in a sequence.
• Ring counter are used to control a sequence of operations, e.g., finite-state machine

Question 6

Issues with ring counters?

Answer 6

• There is no 0 output state.
• If the counter should enter a forbidden state, it cannot recover. Then, it is necessary to clear all the registers and start again.
• Ring counters need a non-zero reset, they should have one flip-flip in state 1.

Question 7

Ring counter-example program?

Answer 7

Question 8

The twisted ring (Johnson) counter?

Answer 8

• This is the similar to a standard ring counter, but the bit that circulates back to the first flip-flop is inverted.
• If all the N registers are initially cleared to zero, the input value of the first register is 1 and remains 1 for N clock pulses.
• This causes 1s to propagate along the chain, not just a single ‘1’.
• When the last flip-flop changes to 1, the first register input becomes 0 and zeros begin to propagate along the chain.

Question 9

TT Four-bit Johnson Counter?

Answer 9

Question 10

TT Ring counter?

Answer 10

Question 11

Difference between Johnson and Ring counters?

Answer 11

• Johnson counter has twice count states from the ring counter.
• The value 0 (zero) is allowed.
• It does not require to set the first count bit.

Question 12

Johnson counters syntax implementation?

Answer 12

Question 13

Linear Feedback Shift Registers (LFSR)?

Answer 13

Question 14

Linear feedback shift registers (LFSR) are used to create:

Answer 14

• Counters
• Generation of pseudo-random sequence of numbers
• Application in cryptography, pseudo-random number generator in ciphers
• Pattern generation

Question 15

Counter XOR module?

Answer 15