Renesas R5S72624 User Manual

 

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

 

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