SAA7327 Datasheet, PDF (39/68 Pages) NXP Semiconductors – Digital servo processor and Compact Disc decoder with integrated DAC for video CD CD7 II

Philips Semiconductors
Digital servo processor and Compact Disc decoder
with integrated DAC for video CD (CD7 II)
Product specification
SAA7327
7.15.3 DECODER REGISTERS AND SHADOW REGISTERS
To maintain compatibility with the SAA737x series,
decoder registers 0 to F are identical to the SAA7370.
However, to control the extra functionality of SAA7327, a
new set of registers called shadow registers have been
implemented.
These are accessed by using the LSB of decoder
register F. This bit is called SHADEN (shadow registers
enable) on SAA7327. When this bit is set to logic 1 (i.e.
decoder register F set to XXX1), any subsequent
addresses will be decoded by the shadow registers.
In fact, only four addresses are implemented as shadow
registers; 3, 7, A and C. Any other addresses sent while
SHADEN = 1 are invalid and have no effect.
When SHADEN is set to logic 0 (decoder register F set to
XXX0) all subsequent addresses are decoded by the main
decoder registers again.
Access to decoder register F is always enabled so that
SHADEN can be set or reset as required.
The SHADEN bit and subsequent shadow registers are
programmed identically to the main decoder registers, i.e.
they can be directly programmed when using SAA7327 in
4-wire mode or programmed via the servo interface when
using 3-wire or I²C-bus modes.
The main decoder registers are shown in Table 14.
The functions implemented using shadow registers are
shown in Table 16.
7.15.4 SUMMARY OF FUNCTIONS CONTROLLED BY DECODER REGISTERS 0 TO F
Table 14 Registers 0 to F
REGISTER
0
(fade and
attenuation)
ADDRESS
0000
1
(motor mode)
0001
DATA
0000
0010
0001
0100
0101
X000
X001
X010
X011
X100
X101
X111
X110
1XXX
0XXX
FUNCTION
mute
attenuate
full-scale
step down
step up
motor off mode
motor stop mode 1
motor stop mode 2
motor start mode 1
motor start mode 2
motor jump mode
motor play mode
motor jump mode 1
anti-windup active
anti-windup off
INITIAL⁽¹⁾
reset
−
−
−
−
reset
−
−
−
−
−
−
−
−
reset
1999 Jun 17
39