comtech aha corporation
Figure 1:
AHA3411 Block Diagram
FUNCTIONAL DESCRIPTION
The coprocessor device has three external high
speed synchronous data ports each capable of
transferring once every 33 MHz clock. These are a
32-bit bidirectional data port, an 8-bit Video Input
Data (VID) port and a Video Output Data (VOD)
port. The data port is capable of transferring up to
132 MBytes/sec. The VID and VOD are capable of
up to 33 MBytes/sec each.
The device accepts uncompressed data through
the data port or optionally through the 8-bit VID
port into its Compression In FIFO (CI FIFO).
Compressed data is available through the data port
via the Compressed Output FIFO (CO FIFO). The
sustained data rate through the compression engine
is 33 MBytes/sec.
Decompression data is accepted through the data
port, buffered in the Decompression Input FIFO (DI
FIFO), and decompressed. The output data is made
available on the data port via the Decompression
Output FIFO (DO FIFO) or optionally on the 8-bit
Video Output port. The decompression engine runs
on the 33 MHz clock and is capable of processing an
uncompressed byte every clock, i.e. 33 MBytes/sec.
The four FIFOs are organized as 16×32 each.
For data transfers through the three ports, the
“effective” FIFO widths differ according to their
data bus widths.
Data transfer for compression or decompression
is synchronous over the three data ports functioning
as DMA masters. To initiate a transfer into or out of
the Video ports, the device asserts VxREQN, the
external device responds with VxACKN and begins
to transfer data over the VID or VOD busses on each
succeeding rising edge of the clock until VxREQN
is deasserted. The data port relies on the FIFO
Threshold settings to determine the transfer.
SYSTEM APPLICATION
The device is intended for memory intensive
applications, such as digital copiers or printers.
These applications require the simultaneous
compression and decompression capability of the
device. Copiers use this feature to feed the
compressed bit maps through the decompressor to
the printer engine while another process uses the
compressor to input and compress scanned images.
Movement for both processes is typically controlled
by a DMA controller that is programmed by the local
microprocessor.
(From Scanner)
VIREQN
VID[7:0]
VIACKN
D[31:0]
DRIVEN
VOACKN
VOD[7:0]
VOREQN
VOEORN
VOEOTN
(To Printer)
COEORN
VID
PORT
DATA
PORT
CI
FIFO
16x32
DI
FIFO
16x32
CLOCK
DATA PORT CONTROL
COMPRESSOR
DECOMPRESSOR
MICROPROCESSOR INTERFACE
CO
FIFO
16x32
DO
FIFO
16x32
VOD
PORT
AHA3411
StarLite
8
8
8
8
8
8
32
32
32
6
8
COEOTN
French ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
