saa7803 NXP Semiconductors, saa7803 Datasheet - Page 35

• Manufacturer Part Number: saa7803
• Description: Saa7803 One Chip Cd Audio Device
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13695
Objective data sheet
6.6.6.4 Main data decoding
Remark: If CDTEXTControl(FREEZEEN) is disabled, the interface is not held during
readback, which means that the current CD-TEXT pack can be overwritten by the next
one before all bytes of the current pack are read out. Such an event will be indicated by
setting CDTEXTReadEnd(BUFFEROVERFLOW) to ‘1’, so that it can be noticed by
software at the end of the pack-read.
The availability of a new CD-TEXT pack will also trigger an interrupt if bit
InterruptEnable1(CDTEXTREADYENABLE) is set.
Data processing:
CD red book CIRC decoding standards and uses an internal SRAM as buffer and FIFO.
The C1 correction will correct up to two errors / EFM-frame, and will flag all uncorrectable
frames as an erasure. The C2 error correction will correct up to two errors or four
erasures, and will also flag all uncorrectable frames as an erasure.
The decoding operation is controlled by the DecoMode register. There are basically two
decode operation modes:
During flush mode, no data is output from the device. During play mode, data is output via
the I
Figure 20
De-interleaving of the data is done in accordance with the red book specification.
De-interleaving is performed by the SRAM FIFO address calculation functions in the
memory processor. Two corrections are done - C1 followed by C2.
Data latency and FIFO operation:
amount of data required in the FIFO to perform the de-interleaving operation. The latency
is quoted in the number of C1 frames (24 bytes of user data). The latency of the CIRC
decoder is 118 frames.
Fig 20. Data processing during CD mode
•
•
demod
from
data
In flush mode, the de-interleaver tables are emptied, and all internal pointers are
reset. No data is written into the buffer, no corrections are done, and no data is output
In play mode, de-interleaver tables are filled, C1 / C2 corrections are done, and data is
output (when available).
2
S-bus interface as soon as it is available in the internal FIFO.
de-interleave
shows the operation of the FIFO and corrections during CD playback.
'd'
correct
The CD main data is de-interleaved and error-corrected according the
C1
Rev. 01 — 19 April 2005
FIFO
The system data latency is a function of the minimum
FIFO filling
de-interleave
'D'
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
One chip CD audio device
correct
C2
SAA7803
001aab764
de-interleave
Delta
to
I
back-end
2
S-bus
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