Abstract: A Delay-tolerant Asynchronous Interface (DANI) is typically used to make the clock domains for reusable silicon intellectual property (IP) cores completely independent of each other. In fact, a DANI-wrapped IP core usually appears to its environment as if it were clockless. This property is necessary to address the variability in data transmission-time between source and destination. This variability is a result of increased lack of predictability in today's leading-edge manufacturing processes. A DANI wrapper can be applied to the IP core that is the source of data to be transmitted or it can be applied to the IP core that is the destination of that data. The transmission time over the route between source and destination may vary more than a single clock period.

Abstract: A digital phase adjustment circuit adjusts the phase between cell signals and a start-of-cell marker. The circuit relies on a known data pattern in unassigned cell signals in order to determine the phase. During a learning mode, the circuit samples an unassigned cell signal several times during a selected cell time to determine the location of the known data pattern. If the data pattern is not at the sampled position, the circuit increments the cell time during which it samples the next unassigned cell signal by one period, and decreases an amount of delay the circuit provides to a selected sample signal by one clock period. In this manner, the circuit can compensate for up to about two periods of delay before sampling the known data pattern. Thereafter, the circuit enters a tracking mode, and tracks phase variations between the cell signals and the start-of-cell marker. Additionally, the circuit selects a sample output signal which replicates the cell signals but is not subject to metastability.