
Hardware Description
MFC 2000 Multifunctional Peripheral Controller 2000
100723A
Conexant
11-3
Once the data is prepared for output by the Bit Rotation Block, it may be retrieved by the External Print ASIC via
the Bit Packer DMA channel. The BRB issues the ready signal to indicate that a halfword of data is ready for
retrieval to the DMA Controller. Then, the DMA Controller will grant the DMA channel 2 access cycle by activating
the DMAACK2 when system bus is available if DMAREQ2 is active and BRB output ready signal is active.
11.2 Block Diagram
A high-level block diagram of the Bit Rotation Block is shown. Note that the internal RAM is double-banked, so
that these operations of fetching and packing can occur simultaneously (however, they are not allowed to occur
to/from the same bank at the same time).
brb_regs
This block is used to hold the internal registers of the BRB. The registers are split into setup registers,
operation registers, and test registers. Each group has a separate chip select sent by the SIU.
brb_memif
This block has three separate interfaces: the SIU, the Swath Fetcher, and the Bit Packer. If a bit
rotation operation is in progress (rotateStart = 1 in the RotCtrl register), SIU local memory access is locked out,
and only the swath Fetcher and Bit Packer blocks may access the memory at this time. If the rotateStart bit is not
set, then the SIU has access to the 1 kB memory through locations 01FF9000h-01FF93FFh.
Swath Fetcher
This block works in conjunction with channel 3 of the DMA Controller to transfer image data from
the swath buffer to the local SRAM for Bit Rotation.
Bit Packer
This block is responsible for the actual rotation of image data. It performs this rotation by picking bits
out the local SRAM and constructing the final rotated output data for the External Print ASIC.
brbsync
The brb_regs and Swath Fetcher blocks operate at the SIUCLK frequencies, while the Bit Packer and
the brb_memif blocks operate at IHSCLK frequencies. The purpose of this block is to synchronize
communications between the internal blocks of the BRB.
Swath Fetcher
brbsync
Control,
Status , and
Data
Registers
Bit Packer
512 x 16 Local SRAM
BRB Control and
register rd/wr
signals
Data Mux
BRB Local SRAM
Memory Controller
ipb_di[15:0]
ipb_do[15:0]
BRB local memory
access control signals
siuclk
ihsclk
resn
BRB Block
DMA control and
handshaking
signals
Figure 11-4. MFC2000 Bit Rotation Block Diagram