Technical information

Chapter 2: Hardware Interface Description
November 15, 2008 G24-L Module Hardware Description 33
Important: In digital audio mode the input and output gains cannot be controlled by AT
commands.
Figure 2-21 illustrates the PCM bus format of the voiceband audio configuration.
Figure 2-21: Voiceband Mode PCM Bus Coding Format
Operating Modes
The G24-L 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-L default power-up audio configuration. Several audio paths are
available in this mode, and their settings can be programmed through the AT command set.
Table 2-10 describes the available audio paths in Basic mode.
Table 2-10:
Basic Mode Audio Paths
Audio Path Input Signal Output Signal Description
Handset MIC SPKR_N, SPKR_P Default audio path for speech and
DTMF tones.
Headset HDST_MIC SPKR_N, SPKR_P Alternate path for headset device.
Enable by setting HDST_INT_N
interface signal low.
Alert ALRT_N, ALRT_P Default alert and ringer loudspeaker
output device.
Digital PCM_DIN PCM_DOUT Enable digital path by
AT+MADIGITAL=1