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Neo FreeRunner

Neo 1973

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 Samsung 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
From: Joerg Reisenweber <>
Date: Thu, 12 Jun 2008 15:48:58 +0200

LOUT2/ROUT2 is handset earpiece (aka receiver).
LOUT1/ROUT1 is routing to external amp, which there is switching between
headset-stereo and device-speaker-mono(GTA02)/stereo(GTA01) via
cpu-GPIO[HP_IN]. (what also is a function I expect to see in alsa-driver of
our "OEM-card", but surely NOT in WM8753-alsa-driver)


MONO1, MONO2: differential output routing to mic analog in of GSM

and while I'm writing...
MIC2,MIC2N: diff. input from handset mic
MIC1,MIC1N: "differential" Input from headset (ring3 jack, MIC1N:GND via 100N)
RXP,RXN: diff. input from GSM analog "earpiece" output
ACOP->AIN via 100N
LINE1, LINE2: to testpoint H-TP3001/2, NC
VXD: digital PCM to BT (mono only?)
DACDAT, ADCDAT: to cpu via IIS

Neo modes

  • 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.

See also

External links