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Implementing Double Data Rate I/O Signaling in Cyclone Devices
Double data rate (DDR) transmission is used in many applications wherefast data transmission is needed, such as memory access and first-infirst-out (FIFO) memory structures. DDR uses both edges of a clock totransmit data, which facilitates data transmission at twice the rate of asingle data rate (SDR) architecture using the same clock speed. Thismethod also reduces the number of I/O pins required to transmit data.This chapter shows implementations of a double data rate I/O interfaceusing Cyclone® devices. Cyclone devices support DDR input, DDRoutput, and bidirectional DDR signaling.f For more information on using Cyclone devices in applications withDDR SDRAM and FCRAM memory devices, see “DDR MemorySupport” on page 10–4.
