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Codiode/Problems/Sequential Logic

BCD Counter: Full Decade Waveform

EasyLogic CircuitTiming Diagram

A positive-edge-triggered BCD (Binary-Coded Decimal) counter increments its 4-bit output by one on every LOW-to-HIGH transition of CLK when EN is HIGH, rolling over to 0000 immediately after reaching 1001 (9).

Six signals are shown: CLK (clock, period 2), EN (count enable input), and Q3, Q2, Q1, Q0 (outputs, initially 0000).

Trace the outputs Q3, Q2, Q1, and Q0 across all 24 time steps to demonstrate a full decade count and the subsequent reset cycle.

Constraints

  • The state transitions strictly on the LOW-to-HIGH edge of CLK.
  • The counter must never enter state 10 (1010).
  • Q3 is the most significant bit (8s place) and Q0 is the least significant bit (1s place).

Topics

sequentialbcdcountersrollover

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