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Codiode/Problems/Sequential Logic

BCD Counter with Enable: Count Preservation

MediumLogic CircuitTiming Diagram

A positive-edge-triggered BCD counter increments its value from 0 to 9 on the rising edge of CLK when EN is HIGH, and holds its current value when EN is LOW.

Six signals are shown: CLK (clock), EN (enable input), and Q3, Q2, Q1, Q0 (outputs representing the 4-bit BCD value, initially 6 or 0110).

Trace the outputs Q3, Q2, Q1, and Q0 across all 16 time steps.

Constraints

  • The counter rolls over directly from 9 (1001) to 0 (0000).
  • State changes only occur exactly on the LOW-to-HIGH transitions of CLK.
  • The EN signal must be evaluated exactly at the moment of the clock edge.

Topics

BCDSequential LogicEnableCounters

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