Parallel data transfer method and system of ddr divided data with associated transfer clock signal over three signal lines

Abstract

A data transfer method allowing improved data transfer speed without increasing the number of signal lines is disclosed. After dividing data to be transferred into odd-numbered data and even-numbered data, the odd-numbered data are sequentially read at timing of a leading edge of each clock pulse and the even-numbered data are sequentially read at timing of a trailing edge of each clock pulse. Thereafter, a data transfer completion indicator is appended to one of the odd-numbered and even-numbered data strings. A transfer clock signal includes a fixed-level pulse in a period of time corresponding to the data transfer completion indicator. The one of the odd-numbered and even-numbered data strings followed by the data transfer completion indicator, the other of the odd-numbered and even-numbered data strings, and the transfer clock signal are transferred through different signal lines.