SH7261 Datasheet, PDF (1028/1348 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 21 CD-ROM Decoder (ROM-DEC)
(1) Automatic Sync Maintenance Mode
In automatic sync maintenance mode, the sync code is ignored if detected within the one-sector
(2352-byte) period. Furthermore, if a sync code is not detected at the point where a next sector
should start, sync code maintenance is applied. If synchronization timing has changed, re-
synchronization is performed at the point where a sync code is detected within 2352 bytes after the
change.
Therefore, this mode is effective in rejecting abnormal sync patterns and following changes in
synchronization timing. Note, however, that this mode cannot achieve synchronization with the
first sector after a change to the synchronization timing.
Figure 21.8 shows operation in the case of normal sync-code detection, figure 21.9 shows a case
where a sync code is detected before a current one-sector period has elapsed, and figure 21.10
shows the case where the actual sync code is only detected some time after a full one-sector period
has elapsed.
Input data
Sync code
detection
Output data
Sector 1
Sector 2
Sector 3
Sector 4
Sector 5
Sector 6
Sector 1
Sector 2
Sector 3
Sector 4
Sector 6
Figure 21.8 Operation in Automatic Sync Maintenance Mode (Normal Timing)
Intput data
Sync code
detection
Abnormal sector
Sector 1
Sector 3
Sector 4
Sector 5
Sector 6
Ignore Maintain Ignore Maintain
Re-synchronization
Output data
Sector 1
Sector 5
Abnormal
sector
Abnormal Abnormal
sector sector
Figure 21.9 Operation in Automatic Sync Maintenance Mode
(When an Abnormally Short Sector is Encountered)
Rev. 2.00 Sep. 07, 2007 Page 996 of 1312
REJ09B0320-0200