XC3S250E Xilinx, Inc., XC3S250E Datasheet - Page 41

• Manufacturer Part Number: XC3S250E
• Description: Spartan-3E FPGA Family
• Manufacturer: Xilinx, Inc.

Functional Description
Setting the WRITE_MODE attribute to a value of
NO_CHANGE, puts the DO outputs in a latched state when
asserting WE. Under this condition, the DO outputs retain
34
Figure 32: Waveforms of Block RAM Data Operations with NO_CHANGE Selected
Figure 31: Waveforms of Block RAM Data Operations with READ_FIRST Selected
Data_in
ADDR
ADDR
Data_in
CLK
CLK
WE
WE
DO
DO
EN
EN
DI
DI
DISABLED
DISABLED
0000
0000
DI
DI
Internal
Internal
Memory
Memory
XXXX
XXXX
aa
aa
READ
READ
MEM(aa)
MEM(aa)
DO
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DO
1111
bb
MEM(bb)=1111
1111
bb
MEM(bb)=1111
WRITE
WRITE
old MEM(bb)
the data driven just before WE is asserted. NO_CHANGE
timing is shown in the portion of
is High.
Prior stored data
No change during write
2222
cc
2222
cc
MEM(cc)=2222
MEM(cc)=2222
WRITE
WRITE
old MEM(cc)
dd
dd
DS312-2_06_020905
DS312-2_07_020905
XXXX
XXXX
READ
READ
Advance Product Specification
MEM(dd)
MEM(dd)
DS312-2 (v1.1) March 21, 2005
Figure 32
during which WE
R