Integration Guide

LEON-G100/G200 - System Integration Manual
GSM.G1-HW-09002-F3 Preliminary System description
Page 61 of 101
Reference
Description
Part Number - Manufacturer
C1, C2, C3, C4
10 µF Capacitor X5R 0603 5% 6.3 V
GRM188R60J106M - Murata
Table 25: Example of components for the connection to an Audio Device
1.10.2 Digital Audio interface
LEON-G100/G200 support a bidirectional 4-wire I
2
S digital audio interface. The module acts as master only. The
I
2
S pins are listed in Table 26:
Name
Description
Remarks
I2S_WA
I
2
S word alignment
Module output (master).
1
I2S_TXD
I
2
S transmit data
Module output
1
I2S_CLK
I
2
S clock
Module output (master)
1
I2S_RXD
I
2
S receive data
Module input
1
Internal active pull-up to 2.85 V enabled.
Table 26: I
2
S interface pins
I
2
S interface pins ESD rating is 1 kV (contact discharge). A higher protection level could be required if the
lines are externally accessible on the application board. A higher protection level can be achieved
mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the lines connected to
these pins if they are externally accessible on the application board.
The I
2
S interface can be can be used in two modes:
PCM mode: I2Sx
Normal I
2
S mode: I2Sy
Beyond the supported transmission modality, the main difference between the PCM mode and the normal I
2
S
mode is represented by the logical connection to the digital audio processing system integrated in the chipset
firmware (see Figure 40):
PCM mode provides complete audio processing functionality
Normal I
2
S mode: digital filters, digital gains, side tone, some audio resources as tone generator, info tones
(e.g. free tone, connection tone, low battery alarm), and ringer are not available
The I
2
S interface is activated and configured using AT commands, see the u-blox 2G GSM/GPRS AT Commands
Manual [2] (AT+UI2S command).
If the I
2
S interface is used in PCM mode, digital path parameters can be configured and saved as the normal
analog paths, using appropriate path index as described in the u-blox 2G GSM/GPRS AT Commands Manual [2].
Analog gain parameters of microphone and speakers are unused when digital path is selected.
Any external signal connected to the digital audio interface must be tri-stated when the module is in
power-down mode and must be tri-stated during the module power-on sequence (at least for 1500 ms
after the start-up event). If the external signals connected to the digital audio interface cannot be
tri-stated, insert a multi channel digital switch (e.g. Texas Instruments SN74CB3Q16244, TS5A3159, or
TS5A63157) between the two-circuit connections and set to high impedance when the module is in
power down mode and during the module power-on sequence.
If the I
2
S pins are not used, they can be left floating on the application board.
1
Check device specifications to ensure compatibility of supported modes to LEON-G100/G200 module. Add a test point to provide access to
the pin for debugging.