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AC75 Hardware Interface Description
Strictly confidential / Preliminary
s
AC75_HD_V00.202
Page 69 of 120
27.04.2006
3.15.4
Digital Audio Interface (DAI)
The DAI can be used to connect audio devices capable of PCM (Pulse Code Modulation) or
for type approval. The following chapters describe the PCM interface functionality.
The PCM functionality allows the use of a codec like for example the MC145483. This codec
replaces the analog audio inputs and outputs during a call, if digital audio is selected by
AT^SAIC.
The PCM interface is configurable with the AT^SAIC command (see [1]) and supports the
following features:
-
Master and slave mode
-
Short frame and long frame synchronization
-
256 kHz or 512 kHz bit clock frequency
For the PCM interface configuration the parameters <clock>, <mode> and <framemode> of
the AT^SAIC command are used. The following table lists possible combinations:
Table 15: Configuration combinations for the PCM interface
Configuration
<clock>
<mode>
<framemode>
Master, 256kHz, short frame 0
0
0
Master, 256kHz, long frame 0
0
1
Master, 512kHz, short frame 1
0
0
Master, 512kHz, long frame 1
0
1
Slave, 256kHz, short frame 0 or 1
1
0
Slave, 256kHz, long frame
0 or 1
1
1
Slave, 512kHz, short frame 0 or 1
1
0
Slave, 512kHz, long frame
0 or 1
1
1
In all configurations the PCM interface has the following common features:
-
16 Bit linear
-
8 kHz sample rate
-
the most significant bit MSB is transferred first
-
125 µs frame duration
-
common frame sync signal for transmit and receive
3
In slave mode the BCLKIN signal is directly used for data shifting. Therefore, the clock frequency setting is not
evaluated and may be either 0 or 1.