Detailed Specifications
2- 88
R e v i sio n 1 8
Note that the RAM blocks employ little-endian byte order for read and write operations.
Modes of Operation
There are two read modes and one write mode:
Read Nonpipelined (synchronous – one clock edge)
Read Pipelined (synchronous – two clock edges)
Write (synchronous – one clock edge)
In the standard read mode, new data is driven onto the RD bus in the clock cycle immediately following
RA and REN valid. The read address is registered on the read-port active-clock edge and data appears
at read-data after the RAM access time. Setting the PIPE to OFF enables this mode.
The pipelined mode incurs an additional clock delay from address to data, but enables operation at a
much higher frequency. The read-address is registered on the read-port active-clock edge, and the read
data is registered and appears at RD after the second read clock edge. Setting the PIPE to ON enables
this mode.
On the write active-clock edge, the write data are written into the SRAM at the write address when WEN
is high. The setup time of the write address, write enables, and write data are minimal with respect to the
write clock.
Table 2-88 RAM Signal Description
Signal
Direction
Description
WCLK
Input
Write clock (can be active on either edge).
WA[J:0]
Input
Write address bus.The value J is dependent on the RAM configuration and the
number of cascaded memory blocks. The valid range for J is from 6 to15.
WD[M-1:0] Input
Write data bus. The value M is dependent on the RAM configuration and can
be 1, 2, 4, 9, 18, or 36.
RCLK
Input
Read clock (can be active on either edge).
RA[K:0]
Input
Read address bus. The value K is dependent on the RAM configuration and
the number of cascaded memory blocks. The valid range for K is from 6 to 15.
RD[N-1:0]
Output
Read data bus. The value N is dependent on the RAM configuration and can
be 1, 2, 4, 9, 18, or 36.
REN
Input
Read enable. When this signal is valid on the active edge of the clock, data at
location RA will be driven onto RD.
WEN
Input
Write enable. When this signal is valid on the active edge of the clock, WD data
will be written at location WA.
RW[2:0]
Input
Width of the read operation dataword.
WW[2:0]
Input
Width of the write operation dataword.
Pipe
Input
Sets the pipe option to be on or off.