WM8753 (also the Wolfson Codec) is the "sound card" chip in the Neo1973 audio subsystem. It has a stereo ADC for recording and a stereo DAC for playback, plus a mono "voice" DAC.
It's connected to the S3C2410 IIS interface for PCM "hi-fi" data, and to the S3C2410 I2C interface for control. The PCM "voice" input and output is connected to the Bluetooth chip. The stereo output ("Audio Out": LOUT1 and ROUT1) is connected to LM4857 stereo input (LIN and RIN) for amplification. MONO1 and MONO2 form "GSM Line Out"; RXP and RXN form "GSM Line In". MIC1 is "Headset Mic", and MIC2 is "Call Mic".
The following output pins are not connected: LOUT2 and ROUT2, OUT3, OUT4. The following input pins are not connected: LINE1, LINE2.
There are several sources connected via switches that can cut each source out:
- "Left Mixer Left" and "Right Mixer Right Playback Switch" connect the stereo DAC for stereo mixing.
- "Mono Mixer Left" and "Mono Mixer Right Playback Switch" connect the stereo DAC for mono mixing.
- XXX bypass, sidetone, voice
- Off: all off.
- GSM Handset: only "Headset Mic" off.
- GSM Headset: only "Call Mic" off.
- GSM Bluetooth: only "Line In" and "Line Out" on.
- Speakers: only "Audio Out" on.
- Headphones: only "Audio Out" on.
- Capture Handset: only "Call Mic" on.
- Capture Headset: only "Headset Mic" on.
- Capture Bluetooth: all off.
- The WM8753 data sheet (PDF)
- asoc-* at OpenMoko kernel patches