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AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.15
Audio Interfaces
AC75 comprises three audio interfaces available on the board-to-board connector:
•
Two analog audio interfaces, both with balanced or single-ended inputs/outputs.
•
Serial digital audio interface (DAI) designed for PCM (Pulse Code Modulation).
This means you can connect up to three different audio devices, although only one interface
can be operated at a time. Using the AT^SAIC command you can easily switch back and
forth.
MICP1
MICN1
MICP2
MICN2
EPP1
EPN1
EPP2
EPN2
VMIC
AGND
DAI0
DAI1
DAI2
DAI3
DAI4
DAI5
DAI6
To suit different types of accessories the audio interfaces can be configured for different
audio modes via the AT^SNFS command. The electrical characteristics of the voiceband part
vary with the audio mode. For example, sending and receiving amplification, sidetone paths,
noise suppression etc. depend on the selected mode and can be altered with AT commands
(except for mode 1).
Both analog audio interfaces can be used to connect headsets with microphones or
speakerphones. Headsets can be operated in audio mode 3, speakerphones in audio
mode 2. Audio mode 5 can be used for direct access to the speech coder without signal pre
or post processing.
When shipped from factory, all audio parameters of AC75 are set to interface 1 and audio
mode 1. This is the default configuration optimized for the Votronic HH-SI-30.3/V1.1/0
handset and used for type approving the Siemens reference configuration. Audio mode 1 has
fix parameters which cannot be modified. To adjust the settings of the Votronic handset
simply change to another audio mode.
AC75_HD_V00.202
MUX
MUX
Digital
Audio
Interface
Figure 23: Audio block diagram
Page 63 of 120
A
MUX
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A
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Air
DSP
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27.04.2006
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