CM118B Datasheet, PDF (12/25 Pages) C-Media Electronics – Highly Integrated & Configurable USB Audio Single Chip

CM118B
Highly Integrated & Configurable USB Audio Single Chip
4.3 Jumper Pins and Mode Settings
Jumper pins can be used to set the configuration of CM118B. These jumper pin settings affect both USB
descriptors and USB audio topology.
4.3.1 MICONLY Pin / Mode Pin and MSEL Pin
If MICONLY pin is switched to 0 (Microphone mode), the recording only function of CM118B is activated and
there’s no playback function declared to the host. At this setting, MODE pin selects MONO/STEREO inputs, and MSEL
pin selects whether the descriptor will have SELECTOR Unit or not. In other cases, when the MICONLY pin is
switched to 1, the device preserved its playback function.
Speaker mode is when MICONLY pin is switched to 1, and MODE pin is also switched to 1, the playback only
function of CM118B is activated and there is no recording function declared to the host. At this setting, MSEL pin is
ignored while only one input terminal, one output terminal and one feature unit is declared in the USB audio
topology. Headset mode is when MICONLY is switched to 1, and MODE pin is switched to 0, the full duplex playback
and recording function is declared to the host. The MSEL pin setting decides to activate MIXER Unit or turn it off.
EEPROM register EE_Stereo, 0x32[0] can be used to determined headset mode with stereo ADC (value set to 1) or
mono ADC (value set to 0) channels.
Topology
Headset
Headset(Stereo MIC, with Mixer)
Headset (Mono Mic, with Mixer)
Headset (Stereo Mic, without Mixer)
Headset (Mono Mic, without Mixer)
Speaker Only
Speaker
Microphone Only
Mono-Mic (with Selector)
Mono-Mic (without Selector)
Stereo-Mic (with Selector)
Stereo-Mic (without Selector)
MICONLY
MODE
1
0
1
0
1
0
1
0
1
1
0
1
0
1
0
0
0
0
MSEL
1
1
0
0
X
1
0
1
0
EE_Stereo¹
1
0
1
0
X
X
X
X
X
1 _{EE_Stereo is only configurable with EEPROM, and for IC default value EE_Stereo is set to 0.}
Datasheet Revision: 1.00
Page 12 / 25
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