LISA-U1 series - System Integration Manual
3G.G2-HW-10002-3
Preliminary
System description
Page 67 of 125
The “GPS data ready” function will provide an improvement in the power consumption of the wireless module.
When power saving is enabled in the wireless module by the AT+UPSV command and the GPS receiver doesn’t
send data by the DDC (I
2
C) interface, the module automatically enters idle-mode whenever possible. With the
“GPS data ready” function the GPS receiver can indicate to the wireless module that it is ready to send data by
the DDC (I
2
C) interface: the GPS receiver can wake up the wireless module if it is in idle-mode, so that data sent
by the GPS receiver will not lost by the wireless module even if power saving is enabled.
The
GPIO4
will provide the “GPS RTC sharing” function (parameter <gpio_mode> of +UGPIOC AT command
set to 5), to provide a RTC (Real Time Clock) synchronization signal at the power up of the u-blox GPS receiver
connected to the wireless module. The pin will be set as
Output, to provide a RTC synchronization signal to the u-blox GPS receiver for RTC sharing if the parameter
<mode> of AT+UGPS command is set to 1 and the parameter <GPS_IO_configuration> of +UGPRF AT
command is set to 32
Output / Low, otherwise (default setting)
The pin that provides the “GPS RTC sharing” function must be connected to the RTC synchronization signal of
the u-blox GPS receiver (i.e. the pin EXTINT0 of the u-blox GPS receiver) on the application board.
The “GPS RTC sharing” function will provide an improvement in the GPS receiver performance, decreasing the
Time To First Fix (TTFF), thus allowing to calculate the position in a shorter time with higher accuracy. When the
GPS local aiding is enabled, the wireless module automatically uploads data such as position, time, ephemeris,
almanac, health and ionospheric parameter from the GPS receiver into its local memory, and restores back the
GPS receiver at next power up of the GPS receiver.
1.11
Audio Interface (LISA-U120 and LISA-U130 only)
LISA-U120 and LISA-U130 modules provide analog and digital audio interfaces:
One differential analog audio input (microphone input)
One differential analog audio output (speaker output)
One 4-wire I
2
S digital audio interface: input and output
Audio signal routing can be controlled by the dedicated AT command +USPM (refer to
u-blox AT Commands
[2]). This command allows setting the audio path mode, composed by the uplink audio path and the
downlink audio path.
Each uplink path mode defines the physical input (i.e. the analog or the digital audio input) and the set of
parameters to process the uplink audio signal (uplink gains, uplink digital filters, echo canceller parameters). For
example the “Headset microphone” uplink path uses the differential analog audio input with the default
parameters for the headset profile.
Each downlink path mode defines the physical output (i.e. the analog or the digital audio output) and the set of
parameters to process the downlink audio signal (downlink gains, downlink digital filters and sidetone). For
example the “Mono headset” downlink path uses the differential analog audio output with the default
parameters for the headset profile.
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 (refer to
u-blox AT Commands Manual
[2] for Audio parameters tuning commands).
1.11.1
Analog Audio interface
1.11.1.1
Uplink path (differential analog audio input)
The pins related to the differential analog audio input are:
