SAA7205 データシートの表示（PDF） - Philips Electronics

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SAA7205

MPEG-2 systems demultiplexer

Philips Electronics 

Philips Semiconductors

MPEG-2 systems demultiplexer

Preliminary specification

SAA7205H

1 FEATURES

• Input data fully compliant with the Transport Stream

(TS) definition of the MPEG-2 systems specification

(International Standard; November 1994)

• Input data signals: Forward Error Correction (FEC) or

descrambler interface

– modem data input bus (8-bit wide)

PKTDAT7 to PKTDAT0

– valid input data indicator (PKTDATV)

– erroneous packet indicator (PKTBAD/PKTBAD)

– first packet byte indicator (PKTSYNC)

– byte strobe signal [for the asynchronous mode only

(PKTBCLK)]

• The interface can be configured to either of two modes:

– asynchronous mode; PKTBCLK < 9 MHz, for

connection to a modem (e.g. FEC)

– synchronous mode; PKTBCLK is not used for

connection to an external descrambler operating at

9 MHz. The descrambler chip clock (9 MHz; 33%

duty cycle) is generated and output to the

demultiplexer.

The descrambler chip clock [DCLK (9 MHz, 33% duty

cycle)] is generated and output by the demultiplexer

• External memory; standard 32K × 8-bit static RAM.

Required typical access time ≤ 50 ns, write pulse width

(tWP) ≤ 35 ns.

• Effective bit rate: fbit ≤ 72 MHz

• Control Interface; 8-bit multiplexed data/address

(MDAT7 to MDAT0), memory mapped I/O (P90CE201

microcontroller parallel bus compatible), in combination

with two microcontroller interrupt signals (IRQ and NMI).

In addition, a number of address input pins

(MA9 to MA2) allow direct access to a selected set of

demultiplexer registers.

• Output ports:

Video; two alternative applications;

– third party video decoder compatible (master or slave

horizontal or vertical sync generation)

– Philips SAA7201 compatible (via general purpose

output)

Audio; third party audio decoder, or Philips SAA2500

compatible

Audio/video; third party combined A/V decoder

compatible, (programmable)

Teletext; a Teletext Clock/Teletext Data (TTC/TTD)

based serial interface to selected teletext decoders

(e.g. SAA9042). Alternatively, this interface can be

programmed to provide data for Vertical Blanking

Interval (VBI) insertion of teletext data. The interface

therefore includes a teletext data request input (TTR).

In this mode, the interface is compatible with the

SAA7183 (EURO-DENC) TXT interface.

HS Data; high-speed data output, outputting entire

transport packets, packet payloads, PES packet

payloads, or sections (programmable) at byte clock

frequency (9 MHz). In the test mode it is capable of

outputting copies of either video, audio or other data

streams (programmable).

HS pins are combined with the general purpose

interface. The general purpose interface is bidirectional,

and can therefore, be used as an alternative transport

stream input.

• Descrambler; 8-bit wide data input interface, combined

with the modem input bus. A descrambler device may

output a descrambled transport stream at 9 MByte/s.

A 9 MHz descrambler clock is generated and output by

the demultiplexer.

• Microcontroller support; only for control, no specific

demultiplexing tasks are performed by the

microcontroller. However, parsing and processing of

Program Specific Information (PSI), and Service

Information (SI) is left to the microcontroller.

• Error handling; stream dependent error handling

algorithms, invoked either if the PKTBAD/PKTBAD input

signal is set, or if the transport_error_indicator bit

(MPEG-2 syntax) is set or if the parser detects an

MPEG-2 syntax error. Different handling algorithms are

applied for the various output ports.

1997 Jan 21

3

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