The ISSI HyperFlash family of products are high-speed CMOS, MirrorBitNOR flash devices with the HyperBus low signal
count DDR (Double Data Rate) interface, that achieves high speed read throughput. The DDR protocol transfers two data bytes per
clock cycle on the data (DQ) signals. A read or write access for the HyperFlash consists of a series of 16-bit wide, one clock cycle
data transfers at the internal HyperFlash core and two corresponding 8-bit wide, one-half-clock-cycle data transfers on the DQ
Both data and command/address information are transferred in DDR fashion over the 8-bit data bus. The clock input signals are
used for signal capture by the HyperFlash device when receiving command/address/data information on the DQ signals. The Read
Data Strobe (RWDS) is an output from the HyperFlash device that indicates when data is being transferred from the memory to the
host. RWDS is referenced to the rising and falling edges of CK during the data transfer portion of read operations.
Command/address/write-data values are center aligned with the clock edges and read-data values are edge aligned with the
transitions of RWDS.
Read and write operations to the HyperFlash device are burst oriented. Read transactions can be specified to use either a wrapped
or linear burst. During wrapped operation, accesses start at a selected location and continue for a configured number of locations in
a group wrap sequence. During linear operation accesses start at a selected location and continue in a sequential manner until the
read operation is terminated, when CS# returns High. Write transactions transfer one or more16-bit values.