Self-Timed Circuit Initialization

In digital circuits, initialization is necessary to set their memory cells to a state that ensures the circuit's correct operation after power-on or restart. Synchronous circuits allow writing to memory cells during circuit operation instead of their initialization if nobody uses the data they store before the first write operation to them. Self-Timed circuits, an alternative to synchronous ones, indicate their state and use an indication signal to acknowledge successful switching completion to the expected state in request-response interaction with the environment. Therefore, their initialization is mandatory. The paper considers the combinational and sequential self-timed circuit initialization features. In most cases, it is sufficient to set all parts of a self-timed circuit to a spacer state. However, as a rule, self-timed latches and flip-flops require presetting a certain state before starting the circuit operation. The paper proposes circuit design methods for initializing self-timed latches, flip-flops, and pipelines that ensure successful ST circuit initialization and prevent hanging of a subcircuit controlling the request-response interactions of functional blocks within the circuit and the entire circuit with its environment.