Integration Manual

LISA-U2 series - System Integration Manual
UBX-13001118 - R25 System description Page 92 of 182
1.11 Audio Interface
All LISA-U2 series modules provide two bidirectional 4-wire I
2
S digital audio interfaces for connecting
to remote digital audio devices:
 First 4-wire I
2
S digital audio interface (I2S_CLK, I2S_RXD, I2S_TXD and I2S_WA)
 Second 4-wire I
2
S 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 [2]). 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 [2] for the audio parameters tuning
commands).
LISA-U2 series modules can act as I
2
S master or I
2
S slave. In master mode, the word alignment and
clock signals of the I
2
S digital audio interface are generated by the module. In slave mode, these
signals must be generated by the remote device.
Table 40 lists the signals related to the digital audio function.
Name
Description
Remarks
I2S_TXD
I
2
S transmit data
Module output
I2S_RXD
I
2
S receive data
Module input
I2S_CLK
I
2
S clock
Module output in master mode
Module input in slave mode
I2S_WA
I
2
S word alignment
Module output in master mode
Module input in slave mode
I2S1_TXD
Second I
2
S transmit data
Module output
I2S1_RXD
Second I
2
S receive data
Module input
I2S1_CLK
Second I
2
S clock
Module output in master mode
Module input in slave mode
I2S1_WA
Second I
2
S word alignment
Module output in master mode
Module input in slave 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 I
2
S 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 I
2
S 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.