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Codiode/Problems/Sequential Logic

I2C Bus Busy Flag

EasyLogic CircuitBuild

Multi-master I2C systems require nodes to monitor ongoing transmissions before asserting control over the shared bus. The bus busy flag prevents collisions by tracking whether a data transaction is currently active.

The circuit maintains a state flag busy that indicates if the bus is in use. It is set to 1 when a start condition is detected (start_det is 1) and cleared to 0 when a stop condition is detected (stop_det is 1). If neither condition is detected, the flag holds its previous state. If both conditions are asserted simultaneously, the stop condition takes priority and clears the bus.

| start_det | stop_det | busy (next) | |-------------|------------|---------------| | 0 | 0 | busy (prev) | | 1 | 0 | 1 | | 0 | 1 | 0 | | 1 | 1 | 0 |

Constraints

  • Implement using asynchronous logic.
  • Do not use clock signals or edge-triggered flip-flops.
  • The stop_det signal must have priority over the start_det signal.

Topics

SequentialLatchInterfaceI2C

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