SAA7380 Datasheet, PDF (17/60 Pages) NXP Semiconductors – Error correction and host interface IC for CD-ROM ELM

Philips Semiconductors
Error correction and host interface IC for
CD-ROM (ELM)
Preliminary specification
SAA7380
Table 7 Error correction modes
DECEN
0
1
1
1
1
1
1
lookahead
X
0
0
0
0
1
1
WRRQ
X
0
0
1
1
1
1
Note
1. Where X = don’t care.
ECCRQ
X
0
1
0
1
0
1
decoder mode
decoder disable; note 1
monitor only
repeat correction
write only
real-time correct, normal mode
write only, lookahead
real-time correct, lookahead
7.7.13 CTRL1
The reset function clears all the flags in this register.
Table 8 CTRL1 register bits
BIT
NAME
FUNCTION
7
SYIEN Disable sync interpolation = 0; Enable sync interpolation = 1. Enabling SYIEN prevents
loss of synchronization when an error occurs in a sync pattern during data read.
6
SYDEN Disable sync detection = 0; Enable sync detection = 1. Enabling SYDEN synchronizes
the decoder with the sync pattern detected in the input data.
5
DSCREN Descramble disable (audio) = 0; Descramble enable = 1. This bit enables/disables
descrambling. Setting this bit to logic 0 allows reading of raw data on disc, even audio
signals. This bit should be set to logic 1 for CROM data.
4
COWREN CRC with error correction disabled = 0; Detection errors are corrected = 1. This bit
enables/disables rewriting of error bytes in the buffer during error correction. Setting
the bit to logic 0 allows CRC checks without error correction.
3
MODRQ Mode 1 request = 0; Mode 2 request = 1. This bit discriminates Mode 1/Mode 2.
2
FORMRQ Form 1 request = 0; Form 2 request = 1. This bit discriminates Mode 2/Form 1 and
Mode 2/Form 2.
1
MBCKRQ Disable mode check function = 0; Enable mode check function = 1. If the mode
specified in the mode byte does not correspond with the raw data mode bit and this bit
is set to logic 1 then error correction and detection is disabled.
0
SHDREN Header data on registers Head0 to Head3 = 0; Sub-header data on registers
Head0 to Head3 = 1. This bit toggles header and sub-header data between registers
HEAD0 to HEAD3.
1996 Apr 25
17