XC3S100E Xilinx Corp., XC3S100E Datasheet - Page 43

• Manufacturer Part Number: XC3S100E
• Description: Spartan-3e Fpga Family Complete Data Sheet
• Manufacturer: Xilinx Corp.

Setting the WRITE_MODE attribute to a value of
WRITE_FIRST, data is written to the addressed memory
location on an enabled active CLK edge and is also passed
to the DO outputs. WRITE_FIRST timing is shown in the
portion of
DS312-2 (v3.6) May 29, 2007
Product Specification
Figure 33
R
Figure 33: Waveforms of Block RAM Data Operations with WRITE_FIRST Selected
Figure 34: Waveforms of Block RAM Data Operations with READ_FIRST Selected
during which WE is High.
Data_in
Data_in
ADDR
ADDR
CLK
CLK
WE
WE
DO
DO
EN
EN
DI
DI
DISABLED
DISABLED
0000
0000
DI
DI
Internal
Memory
Internal
Memory
XXXX
XXXX
aa
aa
READ
READ
MEM(aa)
MEM(aa)
DO
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DO
bb
MEM(bb)=1111
bb
MEM(bb)=1111
1111
1111
WRITE
WRITE
old MEM(bb)
Setting the WRITE_MODE attribute to a value of
READ_FIRST, data already stored in the addressed loca-
tion passes to the DO outputs before that location is over-
written with new data from the DI inputs on an enabled
active CLK edge. READ_FIRST timing is shown in the por-
tion of
Data_out = Data_in
1111
Prior stored data
Figure 34
2222
cc
2222
cc
MEM(cc)=2222
MEM(cc)=2222
WRITE
WRITE
old MEM(cc)
2222
during which WE is High.
dd
dd
DS312-2_05_020905
DS312-2_06_020905
XXXX
XXXX
READ
READ
MEM(dd)
MEM(dd)
Functional Description
43