u-blox SARA-G3 Series User Manual

SARA-G3 series - System Integration Manual
UBX-13000995 - R06 Objective Specification System description
Page 68 of 218
1.10.2 Digital audio interface
SARA-G350 modules provide one 4-wire I
2
S digital audio interface (1.8 V) that acts as an I
2
S master
and can be used for digital audio communication with external digital audio devices that acts as I
2
S slave.
Related pins are:
 I2S_TXD data output
 I2S_RXD data input
 I2S_CLK clock output
 I2S_WA world alignment output
The I
2
S interface can be set to two modes, by the <I2S_mode> parameter of the AT+UI2S command:
 PCM mode
 Normal I
2
S mode
SARA-G350 modules do not support I
2
S slave mode: module acts as master only.
The sample rate is fixed at 8 kHz only: it is not possible to configure the sample rate of
transmitted and received words of SARA-G350 modules.
The <main_uplink> and <main_downlink> parameters of the AT+USPM command must be properly
configured to select the I
2
S digital audio interfaces paths (for more details, refer to u-blox AT Commands
Manual [2]):
 <main_uplink> must be properly set to select:
o the I
2
S interface (using I2S_RXD module input)
 <main_downlink> must be properly set to select:
o the I
2
S interface (using I2S_TXD module output)
Parameters of digital path can be configured and saved as the normal analog paths, using appropriate
path parameter as described in the u-blox AT Commands Manual [2], +USGC, +UMGC, +USTN AT
command. Analog gain parameters of microphone and speakers are not used when digital path is selected.
The I
2
S receive data input and the I
2
S transmit data output signals are respectively connected in parallel
to the analog microphone input and speaker output signals, so resources available for analog path can be
shared:
 Digital filters and digital gains are available in both uplink and downlink direction. The AT commands
allow to properly configure them
 Ringer tone and service tone are mixed on the TX path when active (downlink)
 The HF algorithm acts on I
2
S path
Refer to the u-blox AT Commands Manual [2]: AT+UI2S command for possible settings of I
2
S
interface.

u-blox SARA-G3 Series Specifications

General

Brand	u-blox
Model	SARA-G3 Series
Category	GSM/GPRS Modules
Language	English