SH7261 datasheet(1030/1348 Pages) RENESAS

1030 / 1348 page

Section 21 CD-ROM Decoder (ROM-DEC)

Rev. 2.00 Sep. 07, 2007 Page 998 of 1312

REJ09B0320-0200

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Interpolated Sync Mode

In interpolated sync mode, synchronization is always driven by the internal counter after a sync

code pattern has been detected at the start of decoding. Accordingly, this mode is effective when

the sync patterns have been damaged.

However, decoding becomes incorrect after a change to the synchronization timing, since the

change in timing is not followed.

Figure 21.12 shows the operation in interpolated sync mode.

Abnormal

sector

Abnormal

sector

Abnormal

sector

Abnormal

sector

Sector 1

Intput data

Sync code

detection

Output data

Sector 1

Sector 3

Sector 4

Sector 5

Abnormal sector

Maintain

Ignore

Figure 21.12 Operation in Interpolated Sync Mode

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Interpolated Sync Plus External Sync Mode

In interpolated sync plus external sync mode, synchronization is based on the detected sync code

patterns as long as they are present, and if a sync pattern is not detected at the 2352nd byte, the

sync code maintenance is applied. Synchronization in this mode is more quickly responsive to

changes in synchronization timing than synchronization in the automatic sync maintenance mode.

However, decoding still becomes incorrect when a sync pattern is input with abnormal timing.

SH7261 Datasheet(PDF) 1030 Page - Renesas Technology Corp