A non-source-synchronous system may include a clock-sending device and a clock-receiving device that communicate via a communications bus. The clock-sending device and the clock-receiving device may perform a tuning operation, in which the clock-receiving device sends one or more data signals on one or more data lines of the communications bus to the clock-sending device. The clock-sending device may delay its internal clock signal by an amount based on the one or more data signals. The clock-sending device may then perform sampling of data signals received from the clock-receiving device based on the tuning operation. The tuning operation may be performed in accordance with SDR or DDR, and thus allow for SDR or DDR communication with optimal sampling for systems that do not use a data strobe.