CMI9738 Datasheet, PDF (21/36 Pages) List of Unclassifed Manufacturers – Integrated Multi-channel AC97

6.1 Register Descriptions
Reset Register (Index 00h) (Read Only)
CMI 9738
Integrated Multi-channel AC‘97
Reg Name D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default
00h Reset X SE4 SE3 SE2 SE1 SE0 ID9 ID8 ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0 0000h
No Hardware 3D : SE4…SE0 = 00000b
16 bit ADC & DAC : ID9…ID0 = 0000000000b
Writing this register will reset the mixer register.
Master Volume Registers (Index 02h, 04h and 06h)
Reg
Name D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default
Mut
ML ML ML ML ML
MR MR MR MR MR
02h Master Volume
XX
XXX
0000h
e
43210
43210
Surround Mut
04h
X X X X X X X X X X X X X X 1 X 8000h
Mixer Volume e
‹Each step corresponds to 1.5 dB. The MSB of the register is the mute bit. When this bit is set to 1
the level for that channel is set at ∞ dB.
‹Support for the MSB of the level is optional. If the MSB is not supported then AC ‘97 needs to
detect when that bit is set and set all four LSBs to 1s. Example: If AC ‘97 only supports 5 bits of
resolution in its mixer and the driver writes a 1xxxxx AC ‘97 must interpret that as x11111. It will
also respond when read with x11111 rather
‹then 1xxxxx, the value writen to it. The driver can use this feature to detect if support for the 6th
bit is there or not. The 02h default value is 0000h (0000 0000 0000 0000) , which corresponds to
+12 dB gain with mute off.
Mute
0
Mx5...Mx0
000000
Function
+12 dB gain
0
000001
+10.5 dB gain
0
001000
0 dB Attenuation
0
011110
33.0dB Attenuation
0
011111
46.5dB Attenuation
0
111111
46.5dB Attenuation
1
xxxxxx
∞ dB Attenuation
C-MEDIA Electronics Inc.
6F, 100, Sec. 4, Civil Boulevard, Taipei, Taiwan, R.O.C. 106
TEL: [phone] FAX: [phone] E-mail:[e-mail]
Revision Date Apr./2002
Revision 1.1