HD49235FS Datasheet, PDF (20/41 Pages) Hitachi Semiconductor – Digital Signal Processor for CD

HD49235FS
QOK: The output at this pin indicates whether or not the Q subcode is correct.
One block of Q subcode data consists of 98 bits, of which 16 bits are parity bits that indicate whether
the data read from the disc was correct or in error. An on-chip cyclic redundancy check circuit decides
whether the 98-bit data string is correct or not, and outputs the result at the QOK pin. A high-level
output indicates OK. Figures 7 and 8 show the output timing.
In modes using the Q code buffer register, when the microprocessor sets the CRCQ bit to 1, QOK is
inserted in QDATA at the rise of S1.
See the note in the timing chart shown in figure 7.
EMP: This output pin indicates the presence or absence of pre-emphasis. The pre-emphasis signal is
detected from the Q subcode and output at the EMP pin. High output indicates audio with pre-emphasis.
Low output indicates audio without
pre-emphasis.
SUBOUT: This pin outputs codes R to W for use in display of graphics.
CFCKP: This pin outputs a subcode frame synchronization signal.
S1
QOK
CKEXT
1 2345
80
1 23
QDATA
*
Q4 Q3 Q2 Q1 Q8
Q77
*
Q4 Q3 Q2
Note: * Undefined when CRCQ = 0; QOK when CRCQ = 1 (high when CRC result is OK)
Figure 7 Timing When QDSEL is Low (Q Code Buffer Mode)
CKEXT
CFCKP
7.35 kHz
QDATA
Q96
S0
S1
Q1
S1
QOK
CRC result data: high when OK
Figure 8 Timing When QDSEL is High(Q Code Internal Synchronization Mode,
Standard Speed Playback)
Rev.2, Aug. 1995, page 20 of 41