Cirrus Logic CS4271 - Manual (Page 42)

CS4271
42 DS592F1
8.4 DAC Channel A Volume Control - Address 04h
See 8.5 DAC Channel B Volume Control - Address 05h
8.5 DAC Channel B Volume Control - Address 05h
8.5.1 Mute (Bit 7)
Function:
The DAC output will mute when this bit is set. Though this bit is active high, it should be noted that
the MUTEC pins are active low. The common mode voltage on the output will be retained when this
bit is set. The muting function is effected, similar to attenuation changes, by the Soft and ZeroCross
bits in the Volume and Mixing Control register. The MUTEC pin for the respective channel will become
active during the mute period if the MUTE bit is set. Both the AMUTEC and BMUTEC will become
active if either MUTE register is enabled and the MUTECB=A bit (register 7) is enabled.
8.5.2 Volume Control (Bits 6:0)
Function:
The digital volume control allows the user to attenuate the signal in 1 dB increments from 0 to -127 dB.
Volume settings are decoded as shown in Table 16. The volume changes are implemented as dictat-
ed by the Soft and ZeroCross bits in the DAC Volume & Mixing Control register (see section 8.3.2).
Table 15. ATAPI Decode
ATAPI3 ATAPI2 ATAPI1 ATAPI0 AOUTA AOUTB
0 0 0 0 MUTE MUTE
0 0 0 1 MUTE bR
0 0 1 0 MUTE bL
0 0 1 1 MUTE b[(L+R)/2]
0 1 0 0 aR MUTE
0 1 0 1 aR bR
0 1 1 0 aR bL
0 1 1 1 aR b[(L+R)/2]
1 0 0 0 aL MUTE
1 0 0 1 aL bR
1 0 1 0 aL bL
1 0 1 1 aL b[(L+R)/2]
1 1 0 0 a[(L+R)/2] MUTE
1 1 0 1 a[(L+R)/2] bR
1 1 1 0 a[(L+R)/2] bL
1 1 1 1 a[(L+R)/2] b[(L+R)/2]
7 6 5 4 3 2 1 0
MUTE VOL6 VOL5 VOL4 VOL3 VOL2 VOL1 VOL0
Table 16. Digital Volume Control Example Settings
Binary Code Decimal Value Volume Setting
0000000 0 0 dB
0010100 20 -20 dB
0101000 40 -40 dB
0111100 60 -60 dB
1011010 90 -90 dB