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Codiode/Problems/Sequential Logic

Ring Counter: 3-Phase for Motor Control

MediumLogic CircuitBuild

Stepper motor drive circuits in disk drives and robotics require precisely timed, non-overlapping activation signals. A 3-phase ring counter generates these 120-degree spaced drive pulses by shifting a single active bit through a closed loop.

The circuit must produce three phase outputs: PhaseA, PhaseB, and PhaseC. When rst is 1, the counter must initialize to the state where PhaseA is 1 and the others are 0. On each rising edge of clk when rst is 0, the active high bit shifts to the next phase in the sequence and loops back to the beginning.

| rst | clk | PhaseA | PhaseB | PhaseC | |-------|-------|----------|----------|----------| | 1 | X | 1 | 0 | 0 | | 0 | ↑ | 0 | 1 | 0 | | 0 | ↑ | 0 | 0 | 1 | | 0 | ↑ | 1 | 0 | 0 |

Constraints

  • Implement using exactly three D flip-flops.
  • Wire the output of the final stage directly back to the input of the first stage.
  • Ensure the reset signal initializes the circuit strictly to the 100 state.

Topics

Shift RegistersRing CounterMotor Control

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