RAM 8.0 BUX II Series Guía de usuario Pagina 41

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7 Series FPGAs Memory Resources www.xilinx.com 41
UG473 (v1.11) November 12, 2014
Block RAM Timing Model
Clock Event 1
Read Operation
During a read operation, the contents of the memory at the address on the ADDR inputs
remain unchanged.
•T
RCCK_ADDR
before clock event 1, address 00 becomes valid at the ADDR inputs of
the block RAM.
At time T
RCCK_EN
before clock event 1, enable is asserted High at the EN input of the
block RAM, enabling the memory for the READ operation that follows.
At time T
RCKO_DO
after clock event 1, the contents of the memory at address 00
become stable at the DO pins of the block RAM.
Whenever EN is asserted, all address changes must meet the specified setup and hold
window. Asynchronous address changes can affect the memory content and block
RAM functionality in an unpredictable way.
Clock Event 2
Write Operation
During a write operation, the content of the memory at the location specified by the
address on the ADDR inputs is replaced by the value on the DI pins and is immediately
reflected on the output latches (in WRITE_FIRST mode); when Write Enable (WE) is High.
At time T
RCCK_ADDR
before clock event 2, address 0F becomes valid at the ADDR
inputs of the block RAM.
At time T
RDCK_DI
before clock event 2, data CCCC becomes valid at the DI inputs of
the block RAM.
At time T
RCCK_WE
before clock event 2, write enable becomes valid at the WE
following the block RAM.
At time T
RCKO_DO
after clock event 2, data CCCC becomes valid at the DO outputs of
the block RAM.
Clock Event 4
RST (Synchronous Set/Reset) Operation
During an RSTRAM operation, initialization parameter value SRVAL is loaded into the
output latches of the block RAM. The RSTRAM operation does NOT change the contents
of the memory and is independent of the ADDR and DI inputs.
At time T
RCCK_RST
before clock event 4, the synchronous set/reset signal becomes
valid (High) at the RSTRAM input of the block RAM.
At time T
RCKO_DO
after clock event 4, the SRVAL 0101 becomes valid at the DO
outputs of the block RAM.
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