LC78620E Datasheet, PDF (18/34 Pages) Sanyo Semicon Device – Compact Disc Player DSP

LC78620E
• JP three-value output
MSB
LSB
10110110
10110111
Command
JP THREE VALUE OUTPUT
JP TWO VALUE OUTPUT (earlier scheme)
RES = low
q
The JP three-value output command allows the track jump operation to be controlled from a single pin.
• Track check mode
MSB
LSB
11110000
11111000
11111111
Command
TRACK CHECK IN
TRACK CHECK OUT
TWO BYTE COMMAND RESET
RES = low
q
The LC78620E will count the specified number of tracks minus one when the microprocessor sends an arbitrary
binary value in the range 8 to 254 after issuing either a track check in or a track check out command.
Note: 1. When the desired track count has been input in binary, the track check operation is started by the fall of RWC.
2. During a track check operation the TOFF pin goes high and the tracking loop is turned off. Therefore, feed motor forwarding is required.
3. When a track check in/out command is issued the function of the WRQ signal switches from the normal mode subcode Q standby monitor function
to the track check monitor function. This signal goes high when the track check is half completed, and goes low when the check finishes. The
control microprocessor should monitor this signal for a low level to determine when the track check completes.
4. If a two-byte reset command is not issued, the track check operation will repeat. That is, to skip over 20,000 tracks, issue a track check 201
command once, and then count the WRQ signal 100 times. This will check 20,000 tracks.
5. After performing a track check operation, use the brake command to have the pickup lock onto the track.
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