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Section 23 CD-ROM Decoder
Page 1252 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
23.4.6 Target-Sector Buffering Function
In the CD-ROM decoder, the sector for output can be designated in two ways: automatic
buffering, where the CD-ROM decoder itself detects the presence of target sectors, and manual
buffering, where the target sector for output is designated by software and the software also
recognizes the sectors buffered in the CD-ROM decoder.
The following describes the procedures for setting the registers in the CD-ROM decoder to set up
automatic or manual buffering.
(1) Setting Up Automatic Buffering
Figure 23.16 shows an example of setting up the automatic buffering. Set the relevant CD-ROM
decoder registers and start input of the data stream; the CD-ROM decoder then detects the target
sector and starts the output of the stream data.
Start of automatic buffering setup
End of automatic buffering setup
Set both the CBUF_AUT and
CBUF_EN bits in CBUFCTL0 to 1
Set both the SUBC_EN and
CROM_EN bits in CROMEN to 1
Set CBUFCTL1
Set CBUFCTL2
Set CBUFCTL3
[1] Turn on the automatic buffering function and
enable buffering in the buffer RAM.
[2] Set the minutes value of the target sector.
[3] Set the seconds value of the target sector.
[4] Set the frame value of the target sector.
[5] Enable subcode processing and CD-ROM decoding.
[1]
[2]
[3]
[4]
[5]
Figure 23.16 Example of Setting Up Automatic Buffering