27

PM3394, FLUKE & PHILIPS
ch4
ch3
ch2
ch1
CH1!5.00 V=
CH2!5.00 V=
CH3!5.00 V=
CH4!2.00 V= ALT MTB5.00us- 1.34dv ch2-
1
2
3
4
T
Parallel Data Communications
There are six ICs that communicate with System Control IC202 on the
parallel bus:
ICs on the Parallel Bus
Name Number Purpose
1. Flash ROM IC205 Start up program instructions
2. Hybrid Gate
Array IC601 Expansion port for System Control
IC202
3. SRAM IC204 IC202’s local memory
4. AV Decoder IC401 Audio (AC-3) and Video (MPEG 2)
decoder
5. ARP2 IC303 CD/DVD data processing & separation
6. Servo DSP IC701 Analog servo control
Bi-directional communications between these ICs are accomplished us-
ing the following lines; however, not all ICs use the last three lines:
·Chip Select from IC202
·Address from IC202
·Data (bi-directional)
·Clock from IC202
·Interrupt from destination IC
· Read/Write from IC202

Chip Select Line

System Control IC202 systematically polls each IC on the communica-
tions bus with a chip select signal. This low or high going pulse identifies
the individual destination IC that System Control wants to communicate
with. The chip select output sequence is listed below:
Chip Select Signals from IC202 (active low)
CS Source Destination Pulse
Width/Polarity
1. CS 1 - IC202/pin 10 SRAM IC204 /
HGA IC601
0.56us /–
0.9usec/-
2. CE – IC202/pin 11 Flash ROM IC205 0.56us /–
3. CS 2 – IC202/pin 9 AV Decoder IC401 0.7 & .26
usec/-
4. CS 4 – IC202/pin 7 HGA IC601 0.3usec/-
5. CS 3 – IC202/pin 8 AV Decoder IC401 1.2usec/-
6. XCS – IC601/pin 111 ARP2 IC303 0.3usec/-
7. HCS - IC601/pin 118 Servo IC701 0.3usec/-
Chip Select Waveforms
The following waveforms show the chip select signals going to the S RAM
IC204 (ch 1) and AV Decoder IC401 (ch 2 and 3). They can be compared
to the D1 data (ch 4) to show that the chip select (ch 1-3) signals occupy
more than one bit clock interval. Note that on each of the CS 1 (ch 1) and
CS 2 (ch 2) lines, two different pulse widths are used. These waveforms
were taken with the unit on without a disc being played.
Chip Select signals from IC202 (active low)
Name Location Voltage/div
Channel 1 CS = CS1 IC202/pin 10 5Vp-p
Channel 2 CS = CS2 IC202/pin 9 5Vp-p
Channel 3 CS = CS3 IC202/pin 8 5Vp-p
Channel 4 Data = D1 IC202/pin 26 2Vp-p
Time base 5usec/div.