Self-recovering bus signal detector

摘要

A detector circuit is disclosed that detects bus signal conditions. To detect a START condition, asynchronous sequential logic detects a first bus signal transition (e.g., from high to low) and a second bus signal (e.g., a high signal). The outputs of the asynchronous sequential logic are combined to produce a START signal that can be latched, so that the START signal can be used to wake up a system or for other purposes. To detect a STOP condition, asynchronous sequential logic is set by a transition (e.g., low to high) of the first bus signal and a second bus signal (e.g., a high signal), producing a STOP signal that can be used to reset the asynchronous sequential logic and the latch.

主权项

1. A circuit for detecting bus signals on a bus, the circuit comprising:
first asynchronous sequential logic having a first input for receiving a first bus signal and a second input; first combinational logic having a first input for receiving an output of the first asynchronous sequential logic and a second input for receiving a second bus signal, an output of the first combinational logic coupled to the second input of the first asynchronous sequential logic; second asynchronous sequential logic having a first input for receiving the second bus signal and a second input for receiving the output of the first asynchronous sequential logic; and second combinational logic having a first input for receiving the output of the first asynchronous sequential logic and a second input for receiving the output of the second asynchronous sequential logic, an output of the second combinational logic providing a start signal.