CXD3003 datasheet(81/137 Pages) SONY

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CXD3003R

§4-6. Servo Auto Sequence

This function performs a series of controls, including auto focus and track jumps. When the auto sequence

command is received from the CPU, auto focus, 1-track jump, 2N-track jump, fine search and M-track move

are executed automatically.

The servo is used in an exclusive manner during the auto sequence execution (when XBUSY = low), so that

commands from the CPU are not transferred to the servo, but can be sent to the CXD3003R.

In addition, when using the auto sequence, turn the A.SEQ of register 9 on.

When CLOK goes from low to high while XBUSY is low, XBUSY does not become high for a maximum of

100µs after that point. This is to prevent the transfer of erroneous data to the servo when XBUSY changes

from low to high by the monostable multivibrator, which is reset by CLOK being low (when XBUSY is low).

In addition, a MAX timer is built into this LSI as a countermeasure against abnormal operation due to external

disturbances, etc. When the auto sequence command is sent from the CPU, this command assumes a $4XY

format, in which X specifies the command and Y sets the MAX timer value and timer range. If the executed

auto sequence command does not terminate within the set timer value, the auto sequence is interrupted (like

$40). See [1] "$4X commands" concerning the timer value and range. Also, the MAX timer is invalidated by

inputting $4X0.

Although this command is explained in the format of $4X in the following command descriptions, the timer

value and timer range are actually sent together from the CPU.

(a) Auto focus ($47)

Focus search-up is performed, FOK and FZC are checked, and the focus servo is turned on.

If $47 is received from the CPU, the focus servo is turned on according to Fig. 4-8. The auto focus starts with

focus search-up, and note that the pickup should be lowered beforehand (focus search-down). In addition,

blind E of register 5 is used to eliminate FZC chattering. Concretely, the focus servo is turned on at the falling

edge of FZC after FZC has been continuously high for a longer time than E.

(b) Track jump

1, 10 and 2N-track jumps are performed respectively. Always use this when the focus, tracking, and sled

servos are on. Note that tracking gain-up and braking-on ($17) should be sent beforehand because they are

not involved in this sequence.

• 1-track jump

When $48 ($49 for REV) is received from the CPU, a FWD (REV) 1-track jump is performed in accordance

with Fig. 4-9. Set blind A and brake B with register 5.

• 10-track jump

When $4A ($4B for REV) is received from the CPU, a FWD (REV) 10-track jump is performed in

accordance with Fig. 4-10. The principal difference from the 1-track jump is to kick the sled. In addition,

after kicking the actuator, when 5 tracks have been counted through COUT, the brake is applied to the

actuator. Then, when the actuator speed is found to have slowed up enough (determined by the COUT

cycle becoming longer than the overflow C set with register 5), the tracking and sled servos are turned on.

CXD3003 датащи(PDF) 81 Page - Sony Corporation