XCS05XL Xilinx, XCS05XL Datasheet - Page 15

• Manufacturer Part Number: XCS05XL
• Description: Spartan and Spartan-XL Families Field Programmable Gate Arrays
• Manufacturer: Xilinx

WCLK can be configured as active on either the rising edge
(default) or the falling edge. While the WCLK input to the
RAM accepts the same signal as the clock input to the asso-
ciated CLB’s flip-flops, the sense of this WCLK input can be
DS060 (v1.6) September 19, 2001
Product Specification
DATA OUT
ADDRESS
WCLK (K)
DATA IN
Figure 13: Data Write and Access Timing for RAM
WE
R
WCLK
A[3:0]
T
WE
ILO
D
T
T
T
WSS
DSS
ASS
4
Figure 14: Logic Diagram for the Dual-Port RAM
OLD
T
T
T
T
WOS
DHS
WHS
AHS
T
WPS
NEW
4
T
DS060_13_080400
ILO
Spartan and Spartan-XL Families Field Programmable Gate Arrays
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1-800-255-7778
4
inverted with respect to the sense of the flip-flop clock
inputs. Consequently, within the same CLB, data at the
RAMs SPO line can be stored in a flip-flop with either the
same or the inverse clock polarity used to write data to the
RAM.
The WE input is active High and cannot be inverted within
the CLB.
Allowing for settling time, the data on the SPO output
reflects the contents of the RAM location currently
addressed. When the address changes, following the asyn-
chronous delay T
location will appear on SPO. If the data at a particular RAM
address is overwritten, after the delay T
will appear on SPO.
Dual-Port Mode
In dual-port mode, the function generators (F-LUT and
G-LUT) are used to create a 16 x 1 dual-port memory. Of
the two data ports available, one permits read and write
operations at the address specified by A[3:0] while the sec-
ond provides only for read operations at the address speci-
fied independently by DPRA[3:0]. As a result, simultaneous
read/write operations at different addresses (or even at the
same address) are supported.
The functional organization of the 16 x 1 dual-port RAM is
shown in
CONTROL
CONTROL
WRITE
WRITE
16 x 1
16 x 1
RAM
RAM
Figure
READ
READ
OUT
OUT
14. The dual-port RAM signals and the
ILO
, the data stored at the new address
4
DS060_14_043001
DPRA[3:0]
SPO
DPO
WOS
, the new data
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