Ublox SARA-G300, Руководство по системной интеграции

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SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26 System description
Page 70 of 217
1.10.2 Digital audio interface
SARA-G340, SARA-G350 and SARA-U2 modules provide one 1.8 V bidirectional 4-wire (
I2S_TXD
data output,
I2S_RXD
data input,
I2S_CLK
clock,
I2S_WA
world alignment) I
2
S digital audio interface that can be used for
digital audio communication with external digital audio devices as an audio codec.
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
The I 2 S interface can be set to two configurations, by the <I2S_Master_Slave> parameter of AT+UI2S:

Master mode

Slave mode
SARA-G340 and SARA-G350 modules do not support I 2 S slave mode: module acts as master only.
The sample rate of transmitted/received words can be set, by the <I2S_sample_rate> parameter of AT+UI2S, to:

8 kHz

11.025 kHz

12 kHz

16 kHz

22.05 kHz

24 kHz

32 kHz

44.1 kHz

48 kHz
SARA-G340 and SARA-G350 modules do not support the <I2S_sample_rate> parameter of AT+UI2S: the
sample rate is fixed at 8 kHz only.
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, see the u-blox AT Commands Manual [3]):

<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 described in the u-blox AT Commands Manual [3],
+USGC, +UMGC, +USTN AT commands. Analog gain parameters 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

Ringer tone and service tone are mixed on the TX path when active (downlink)

The HF algorithm acts on the I
2
S path
See the u-blox AT Commands Manual [3]: AT+UI2S command for possible settings of the I
2
S interface.
I 2 S pins of SARA-G3 modules product versions “02” onwards can be used additionally for diagnostics.