Audio Interface
36 Module Hardware Description January 1, 2006
Figure 2-23 illustrates the PCM bus format of the voiceband audio configuration.
Figure 2-23: Voiceband Mode PCM Bus Coding Format
Stereo Audio
The digital stereo audio format is used for sounding stereo ring tones and alerts. It incorporates 3
modes of operation that support the different audio sampling rates, which are provided by G24 as
ring tone melodies. The available ring tones may be selected by the AT+CRTT command.
The PCM bus signal's configuration for stereo ring tones and alerts is:
• PCM_CLK - 705 kHz - 1.4 MHz serial clock
• PCM_FS - 22.05 kHz - 44.1 kHz word-wide frame-sync
• PCM_DOUT - 16-bit linear audio data output
• PCM_DIN - Disabled
Figure 2-24 illustrates the PCM bus format of the stereo audio configurations.
Figure 2-24: Stereo Mode PCM Bus Coding Format
Operating Modes
The G24 audio interface includes 2 modes of operation. Each operating mode defines the audio
input and output devices to be used for each audio sound type and their programmable settings.
Basic Mode
Basic audio mode is the G24 default power-up audio configuration. Several audio paths are
available in this mode, and their settings can be programmed through the AT command set.
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