43
PM3394, FLUKE & PHILIPS
ch4
ch3
ch2
ch1
CH1!2.00 V=
CH2!2.00 V=
CH3!2.00 V=
CH4!2.00 V= ALT MTB 250ns- 1.06dv ch1-
1
2
3
4
T
PM3394, FLUKE & PHILIPS
ch3
ch2
ch1 ch1: freq= 79.4kHz
CH1!2.00 V=
CH2!2.00 V=
CH3!2.00 V= ALT MTB5.00us ch1+
1
2
3
T
PM3394, FLUKE & PHILIPS
ch3
ch2
ch1 ch1: freq= 79.4kHz
CH1!2.00 V=
CH2!2.00 V=
CH3!2.00 V= ALT MTB5.00us ch1+
1
2
3
T
Sled Still Sled Outward
IC601 and IC701 Communications
Name From IC When Present
1. Chip
Select System Control IC202 Power on/off, playback, tray
open close, and start/stop..
2. Read System Control IC202 Always when powered on
3. Write System Control IC202 Completion of command
(PB, pause, pwr on/off)
4. Interrupt Servo IC701 Completion of command
(PB, pause, pwr on/off)
Address Bi-directional Always when powered on
Data Bi-directional Always when powered on
Bi-directional communications between IC601 and IC701 are similar to
that described for IC202 and IC601. The differences are in the IC pin
numbers and that IC601-IC701 communications are only taking place when
a servo command is changed.
Communications Waveforms
The following waveforms were taken during a sled forward command ini-
tiated from the service mode. They show IC701/pin 3 being chip selected
when low (ch 1). This means 16 bits of data (HD0-15) can be transferred
at each clock interval when this line is low. The chip select pulse is as
wide as three clock intervals. Consequently three groups of data (HD0-
15 =16 bits) can be written or read by IC202.
The write line (ch 3) goes low during the chip select interval (ch 1) to
identify the direction of the (sled forward) bus data into Servo IC701. The
read line is high during this time, meaning it is inactive. The interrupt
signal will go low later on after the sled fast forward movement has been
completed (ch 4).
IC601 to IC701 Communications Waveforms
Name Location Voltage/div
Channel 1 Chip Select (HCS) IC701/pin 3 2Vp-p
Channel 2 Read (HRD) IC701/pin 1 2Vp-p
Channel 3 Write (HWR) IC701/pin 2 2Vp-p
Channel 4 Interrupt (HINT) IC701/pin 128 2Vp-p
Time base 0.25usec/div.
Servo DSP IC701 Issues Analog Commands to Driver IC802
Digital commands from IC202 (via IC601) tell Servo IC701 to perform
sled operations. First IC701 sends an interrupt signal to IC202 (via IC601),
followed by data about the in limit sensor. This data tells IC202 if the laser
is at home position (IC701/pin 23 = 0.7V = home).
If the laser is not at home position, IC202 data to the Servo IC701 in-
structs it to rotate the sled motor until home position is reached.
The sled output of Servo IC701 consists of three 50% duty cycle in phase
square waves at about 80kHz. The square wave from IC701/pin 7 is
used as reference and does not change. If the square wave from pin 8 or
9 decreases in width, the sled motor rotates. This can be seen in the
following waveforms.
Sled Motor Stop Waveforms
The following waveforms were taken of the square waves from IC701
when the sled motor is not turning and when it is moving away from the
spindle shaft (outward).