Technical information

Chapter 2: Hardware Interface Description
December 15, 2009 G30 - Module Hardware Description 37
Figure 2-20 illustrates the I
2
S bus format.
Figure 2-20: I
2
S BUS Format
The PCM bus signal's configuration for voiceband audio is:
• PCM_CLK - 144 kHz serial clock
• PCM_FS - 8 kHz bit-wide frame-sync
• PCM_DOUT - 16-bit linear audio data output
• PCM_DIN - 16-bit linear audio data input
The 16-bit serial data is transferred in both directions after each sync signal's falling edge. The
sync signal pulse duration is two clock periods, after which the serial data is transferred in both
directions for 16 consecutive clock periods.
Following the 16-bit data transfer, the serial input and output data signals inactivate until the next
sync pulse, which occurs every 125 µS (8 kHz). It is recommended the serial data signals will be
High-Z during the inactive period.
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 G30 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 G30 default power-up audio configuration. Several audio paths are
available in this mode, and their settings can be programmed through the AT command set.