Filter
Top Products
Section 23 CD-ROM Decoder
R01UH0134EJ0400 Rev. 4.00 Page 1243 of 2108
Sep 24, 2014
SH7262 Group, SH7264 Group
Figure 23.7 shows a case of input stream data that has no padding (H'12345678). The upper and
lower 16 bits of data are swapped (H'56781234) for input to the CD-ROM decoder.
H'1234
H'1234 is input first.
H'5678 is input next.
H'5678
Core of CD-ROM decoder
BUFEND1[1:0] = 01
BYTEND = 0
H'1234
BUFEND0[1:0] = 10
H'5678
H'1234
H'5678
STRMDIN0
STRMDIN2
H'012 H'34 H'56 H'78
Figure 23.7 Example of Non-Padded Stream Data Control by the SSI Register
23.4.2 Sync Code Maintenance Function
Each sector of CD-ROM data consists of 2352 bytes starting with
H'00FFFFFFFFFFFFFFFFFFFF00 (sync code). However, a scratch on the disc or some other
factor might lead to erroneous recognition of the sync code sequence at the wrong time.
Conversely, a sync code might not be detected at a point where it should be detected. As a solution
to these problems, the CD-ROM decoder of this LSI has a sync-code maintenance function, which
operates to ignore sync codes detected at abnormal times and maintain the appearance of the sync
code at the expected times when it is not actually detected on the disc.
The operating modes of the sync-code maintenance function are listed below. For details on the
settings, refer to section 23.3.2, Sync Code-Based Synchronization Control Register (CROMSY0),
and table 23.2.
Automatic sync maintenance mode
External sync mode
Interpolated sync mode
Interpolated sync plus external sync mode