Specifications

AC65/AC75 Hardware Interface Description
3.15 Audio Interfaces
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AC65_AC75_HD_v01.002 Page 62 of 117 2006-10-30
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3.15.3 Loudspeaker Circuit
The GSM module comprises two analog speaker outputs: EP1 and EP2. Output EP1 is able to drive a load of
8Ohms while the output EP2 can drive a load of 32Ohms. Each interface can be connected in differential and in
single ended configuration. Figure 27 shows an example of a differential loudspeaker configuration.
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 com-
mand are used. The following table lists possible combinations:
Figure 27: Differential loudspeaker configuration
Loudspeaker impedance
EPP1/EPN1
Z
L
= typ. 8Ohm
EPP2/EPN2
Z
L
= typ. 32Ohm
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
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.
10
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