LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 92 of 183
C1-Public
1.11
Audio Interface
All LISA-U2 series modules provide two bidirectional 4-wire I2S digital audio interfaces for connecting
to remote digital audio devices:
•
First 4-wire I2S digital audio interface (
I2S_CLK
,
I2S_RXD
,
I2S_TXD
and
I2S_WA
)
•
Second 4-wire I2S digital audio interface (
I2S1_CLK
,
I2S1_RXD
,
I2S1_TXD
and
I2S1_WA
)
Audio signal routing can be controlled by the dedicated AT command +USPM (see the u-blox AT
commands manual
). This command allows setting the audio path mode, composed by the uplink
audio path and the downlink audio path.
Each uplink and downlink path mode defines the physical input / output, the set of parameters to
process the uplink audio signal (uplink gains, uplink digital filters, echo canceller parameters) and the
set of parameters to process the downlink audio signal (downlink gains, downlink digital filters and
sidetone).
The set of parameters to process the uplink or the downlink audio signal can be changed with
dedicated AT commands for each uplink or downlink path and then stored in two profiles in the non-
volatile memory (see the u-blox AT commands manual
for the audio parameters tuning
commands).
LISA-U2 series modules can act as I2S host or I2S local device . In host mode, the word alignment and
clock signals of the I2S digital audio interface are generated by the module. In local device mode, these
signals must be generated by the remote device.
lists the signals related to the digital audio function.
Name
Description
Remarks
I2S_TXD
I2S transmit data
Module output
I2S_RXD
I2S receive data
Module input
I2S_CLK
I2S clock
Module output in host mode
Module input in local device mode
I2S_WA
I2S word alignment
Module output in host mode
Module input in local device mode
I2S1_TXD
Second I2S transmit data
Module output
I2S1_RXD
Second I2S receive data
Module input
I2S1_CLK
Second I2S clock
Module output in host mode
Module input in local device mode
I2S1_WA
Second I2S word alignment
Module output in host mode
Module input in local device mode
CODEC_CLK
Digital clock output
Digital clock output for external audio codec
Configurable to 26 MHz or 13 MHz
Table 40: Digital audio interface pins
☞
The I2S interfaces and
CODEC_CLK
pins’ ESD sensitivity rating is 1 kV (Human Body Model
according to JESD22-A114F). Higher protection levels could be required if the lines are externally
accessible on the application board. Higher protection levels can be achieved by mounting a
general purpose ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) on the lines
connected to the I2S interfaces pins, close to the accessible points, and a low capacitance (i.e. less
than 10 pF) ESD protection (e.g. AVX USB0002) on the line connected to
CODEC_CLK
pin, close
to the accessible point.
