MN85571AC Datasheet, PDF (13/16 Pages) Panasonic Semiconductor – Single-Chip Audio/Video MPEG2 Encoder

MN85571AC
s Interfaces (continued)
2. DMA transfer interface (DIF)
The DMA transfer interface (DIF) transfers data using DMA between the external host and this device’s DMA data
transfer buffer memory (WRDM). Since WRDM has a size of 1 024 32-bit words, the maximum valid data count is
2 048.
(This function is valid when the CHIPCTL0 direct addressing access register dmasel bit is 0.)
The WRDM can be accessed in two ways: by read or write instructions from the SRISC and by DMA data transfers
(read or write) from the external host.
Since there are two techniques, which technique gains access is arbitrated by the DIF internal arbitration circuit.
Access requests to the arbitration circuit are issued from the SRISC by instruction execution, and from the external
host by writing a 1 to the DIFACC (HA[3:0] = $A) req register (a direct addressing register). If requests are issued to
the arbitration circuit at the same time, access permission is granted according to the priority determined by the value
of the difreg ($0020) indirect addressing access register.
Note that there are two DMA transfer modes: “single bus cycle DMA transfer mode”, in which access is
synchronized with the DMA clock signal (DMACLK), and “two bus cycle DMA transfer mode”, in which transfers
are not dependent on a clock signal.
3. Code output interface
The code output interface is provided to transfer data to a communication system or to the storage system media and
outputs a multiplexed AV bit stream to external circuits.
There are two major classes of output formats provided by the code output interface: “standalone mode (8-bit
parallel)”, which outputs the bit stream using a dedicated set of pins, and “DMA transfer mode (16-bit parallel) which
outputs using an external host bus shared with the host interface.
The setting of the CHIPCTL0 dma sel register (a direct addressing register) selects which of these two output formats
is used. If this bit is set to 0, standalone mode is used, and if set to 1, DMA transfer mode is used.
Additionally, there are three clock modes in standalone mode. These consist of two modes that use a code output clock
(RCLKI) input to this device, “inverted clock input standalone mode”, and “noninverted clock input standalone mode
as well as a mode that uses a code output clock (RCLKO) output from this device, “ARIB parallel interface standard
mode (TS output)”.
Also note that there are two DMA transfer modes which differ in the number of bus cycles required to transfer data,
“single bus cycle DMA transfer mode” and “two bus cycle DMA transfer mode”.
The table below summarizes these modes, and lists the clock frequencies, pins, and other items used in each mode.
Note that in every one of these modes, the maximum amount of valid output data per single handshake operation is
2 048 bytes, and that the maximum average output bit rate is 15 Mbps.
Mode
Standalone Inverted/noninverted
mode
clock input
ARIB parallel
interface standard
DMA
transfer
mode
Single bus cycle
Two bus cycle
Pin names used
Clock frequencies Output data format
CDO[7:0], CDREADY,
RCLKI
CDACK, RCLKI, (IPIC, VOB)³ 16 MHz maximum
MSB
first
CDO[7:0], CDREADY,
RCLKI, IPIC, (VOB)³
RCLKO
MSB
6.75 MHz, 3.375 MHz first
HD[15:0], NHDREQ,
NHDACK, DMACLK
DMACLK
33 MHz maximum
Big Endian/
Little Endian
HD[15:0], NHCS, HA[3:0],
NHRE, NHWE, NHDREQ
Clock signal not
required
Big Endian/
Little Endian
SDD00023AEM
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