Philips DVDR985 Technical Training Manual page 77

MPEG2 Decoder
Playback
During playback, the serial data from the Basic
Engine goes directly to the MPEG2/AC3
Decoder, IC7200 via the serial Front End I 2 S
Interface. Refer to Figure 39. IC7200 is a
MPEG2 Audio/Video Decoder and has the fol-
lowing outputs to the Analog Board: RGB, YC,
CVBS, I 2 S Audio, (PCM format) and SPDIF
Audio (Digital Audio output). IC7200 is the
source of the I 2 C bus on the Digital Board.
MPEG2 decoding is preformed in IC7200.
IC7200 uses SDRAM for its many functions.
The Basic Engine provides to the MPEG2
Decoder serial data from the disc on Pins 17-22.
The A/V Demultiplexer separates the Audio and
Video data. IC7200 also contains the analog
Video Encoder. It provides RGB, Y/C and PCM
audio to the Analog Board.
There is another video output path from IC7200.
The Digital Video for the progressive scan circuit,
PSCAN_YUV(0-7).
Record
It produces the Parallel video output path. The
Parallel Video path sends the recordable video
and audio back to the outputs during the record
process. It receives the selected Multiplexed
Data stream from the VSM via the
D_PAR_D(0,7) lines. There are support signals
for the Parallel Data Stream on Pins 196, 201,
205, and 206. Because of the amount of pro-
cessing, the output video is delayed about 6 sec-
onds.
ComPair
The Compair service aid connects to 7200 via a
serial communication port. Using compair soft-
ware and a computer's COM Port, service trou-
bleshooting and settings can be performed.
Compair has a dedicated connection on the
Digital Board, 1901. The input Pins for 7200 are
2, 3, 197, 200, and, 204. Compair cannot func-
tion if 7200 does not initialize properly.
Power On
IC7200 participates in the initilazation of the unit.
Power up occurs in two stages. 7200 participates
in the second stage. After the Analog board and
the Front Panel Microcomputer check the unit
and pass their tests, the Analog Microcomputer
turns On the Standby supplies. This includes the
3.3Vdc supply for 7200. 7200 then receives the
DIG_Resetn signal from the Analog Board.
7200 creates three reset outputs for the Digital
Boards. Resetn_VE goes to the EMPRESS.
RSTN_DIVIO goes to the DIVIO Board.
RSTN_BE goes to the BE. EMPRESS_BOOT
signal goes to the EMPRESS for its start up flag.
If 7200 passes its self test and the other ICs
communicate properly, the unit's power will stay
On. If not, the unit will go into Sleep mode, never
looking for keyboard input again. This process
has 10 Seconds to occur. If it does not, the
Analog Microcomputer will place the unit in sleep
mode, turning Off the Standby supplies which is
the VCC for most of the ICs on the Digital
Boards.
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