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Codiode/Problems/Sequential Logic

Mod-60 Counter: Tens Digit Wrong Modulus Debug

HardLogic CircuitDebug

A Mod-60 counter tracks seconds and minutes in digital clocks by cascading a mod-10 ones digit and a mod-6 tens digit.

Expected behavior:

The counter increments on each active clock edge when En is high. When the count reaches 59 (Tens = 5, Ones = 9), the next clock pulse must roll the count over to 00 (Tens = 0, Ones = 0). Asserting Rst asynchronously clears both digits to 0.

Simulation shows the count reaching 75 (Tens = 7, Ones = 5) instead of rolling over after 59. The counter sequence fails to reset at the correct modulus.

Inspect the circuit and correct the fault.

Constraints

  • Do not modify the ones digit counter.
  • Only replace or rewire the faulty component to restore the correct modulus.
  • The Tens and Ones outputs must remain 4-bit wide.

Topics

BCDDebugSequential LogicCounters

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