Constraints file signal names, Qdr (quad data rate), Figure 8: zbt constraints file signal names – Sundance SMT398 User Manual
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Version 1.2.0
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SMT398 User Manual
Constraints File Signal Names
Z x C S 2 N
Z B T B a n k n a m e :
x = 1 , 2 , 3 , 4
A c t i v e l e v e l :
N = A c t i v e l o w
Z B T s i g n a l
Z Z , C L K Z B T a r e s i g n a l s
c o m m o n t o a l l m e m o r y
c o m p o n e n t s
Figure 8: ZBT Constraints file signal names
QDR (Quad Data Rate)
Up to 8 Mbytes of
memory is provided with direct access to the FPGA. (Provision has been made to
accommodate up to 64 Mbytes of QDR when the memory chips will be available)
The QDR operation is possible by supporting DDR (Double Data Rate) read and
writes operations through separate data output and input ports with the same cycle.
Memory bandwidth is maximized as data can be transferred into SRAM on every
rising edge of the write clock, and transferred out of SRAM on every rising edge of
the read clock. (Read clock is write clock shifted of 90 degrees)
And totally independent read and write ports eliminate the need for high-speed bus
turn around. The memory is expected to be clocked at 166 MHz allowing a data
throughput rate of 1.3 GBytes/s.
The memory bank of the SMT398 is composed of 2 devices added in parallel in width
expansion architecture. The address bus, input clocks, R# and W# are common to
both devices. The data buses are not common.