EGS5 Hardware Interface Description
3.15 Audio Interfaces
75
EGS5_HD_v02.004
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2012-02-09
Confidential / Released
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^SA-
IC.
The PCM interface is configurable with the AT^SAIC command (see
) and supports the fol-
lowing 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:
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
shows the assignment of the DAI0...6 signals to the PCM interface signals. To avoid
hardware conflicts different lines are used as inputs and outputs for frame sync and clock sig-
nals in master or slave operation. The table shows also which line is used for master or slave.
The data lines (TXDAI and RXDAI) however are used in both modes. Unused inputs should be
tied to GND via pull down resistors. In addition, DAI1 requires a 47kOhm pull down resistor to
be placed as close as possible to the module. Unused outputs must be left open.
Table 17:
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
1.
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.
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
