Axcelerator Family FPGAs
1- 4
v2.8
Embedded Memory
As mentioned earlier, each core tile has either three (in a
smaller tile) or four (in the regular tile) embedded SRAM
blocks along the west side, and each variable-aspect-
ratio SRAM block is 4,608 bits in size. Available memory
configurations are: 128x36, 256x18, 512x9, 1kx4, 2kx2 or
4kx1 bits. The individual blocks have separate read and
write ports that can be configured with different bit
widths on each port. For example, data can be written in
by eight and read out by one.
In addition, every SRAM block has an embedded FIFO
control unit. The control unit allows the SRAM block to
be configured as a synchronous FIFO without using core
logic
modules.
The
FIFO
width
and
depth
are
programmable. The FIFO also features programmable
ALMOST-EMPTY (AEMPTY) and ALMOST-FULL (AFULL)
flags in addition to the normal EMPTY and FULL flags. In
addition to the flag logic, the embedded FIFO control
unit also contains the counters necessary for the
generation of the read and write address pointers as well
as
control
circuitry
to
prevent
metastability
and
erroneous operation. The embedded SRAM/FIFO blocks
can be cascaded to create larger configurations.
I/O Logic
The Axcelerator family of FPGAs features a flexible I/O
structure, supporting a range of mixed voltages with its
bank-selectable I/Os: 1.5V, 1.8V, 2.5V, and 3.3V. In all,
Axcelerator FPGAs support at least 14 different I/O
standards (single-ended, differential, voltage-referenced).
The I/Os are organized into banks, with eight banks per
device (two per side). The configuration of these banks
determines the I/O standards supported (see
"User I/Os"available in each bank.
Each I/O module has an input register (InReg), an output
register (OutReg), and an enable register (EnReg)
modules, four RX modules, two TX modules, and a buffer
(B) module.
Figure 1-6 AX Device Architecture (AX1000 shown)
Chip Layout
SuperCluster
I/O Structure
See Figure 7
RAMC
HD
SC
HD
SC
HD
SC
HD
SC
HD
SC
HD
SC
HD
SC
RD
SC
HD
SC
HD
SC
HD
SC
HD
SC
HD
SC
HD
SC
Core Tile
4k
RAM/
FIFO
4k
RAM/
FIFO
4k
RAM/
FIFO
4k
RAM/
FIFO
RX
TX
B
C
R
C
R
RX
TX