LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 99 of 183
C1-Public
•
Mandatory sub-functions:
o
Discontinuous transmission, DTX (GSM 46.031, 46.041, 46.081 and 46.093 standards)
o
Voice activity detection, VAD (GSM 46.032, 46.042, 46.082 and 46.094 standards)
o
Background noise calculation (GSM 46.012, 46.022, 46.062 and 46.092 standards)
•
Function configurable via specific AT commands (see the u-blox AT commands manual
o
Signal routing: +USPM command
o
Analog amplification, Digital amplification: +USGC, +CLVL, +CRSL, +CMUT command
o
Digital filtering: +UUBF, +UDBF commands
o
Hands-free algorithms (echo cancellation, Noise suppression, Automatic Gain control) +UHFP
command
o
Sidetone generation (feedback of uplink speech signal to downlink path): +USTN command
o
Playing/mixing of alert tones:
▪
Service tones: Tone generator with 3 sinus tones +UPAR command
▪
User generated tones: Tone generator with a single sinus tone +UTGN command
▪
PCM audio files (for prompting): The storage format of PCM audio files is 8 kHz sample
rate, signed 16 bits, little endian, mono
1.12
General Purpose Input/Output (GPIO)
LISA-U2 series modules provide up to 14 pins (
GPIO1
-
14
) which can be configured as general purpose
input or output, or can be configured to provide special functions via u-blox AT commands (for further
details, see the u-blox AT commands manual
, +UGPIOC, +UGPIOR, +UGPIOW, +UGPS, +UGPRF,
+USPM).
The following functions are available in the LISA-U2 modules:
GSM Tx burst indication:
GPIO1
pin can be configured by AT+UGPIOC to indicate when a GSM Tx burst/slot occurs, setting the
parameter <gpio_mode> of AT+UGPIOC command to 9.
No GPIO pin is configured by default to provide the “GSM Tx burst indication” function.
The pin configured to provide the “GSM Tx burst indication” function i
s set as
•
Output / High, since ~10 µs before the start of first Tx slot, until ~5 µs after the end of last Tx slot
•
Output / Low, otherwise
The pin configured to provide the “GSM Tx burst indication” function can be connected on the
application board to an input pin of an application processor to indicate when a GSM Tx burst/slot
occurs.
GNSS supply enable:
The
GPIO2
is by default configured by AT+UGPIOC command to enable or disable the supply of the u-
blox GNSS receiver connected to the cellular module.
The
GPIO1
,
GPIO3
,
GPIO4
or
GPIO5
pins can be configured to provide the “GNSS supply enable”
function, alternatively to the default
GPIO2
pin, setting the parameter <gpio_mode> of AT+UGPIOC
command to 3. The “GNSS supply enable” mode can be provided only on one pin at a time: it is not
possible to simultaneously set the same mode on another pin.
The pin configured to provide the “GNSS supply enable” function is set as
•
Output / High, to switch on the u-blox GNSS receiver, if the parameter <mode> of AT+UGPS
command is set to 1
•
Output / Low, to switch off the u-blox GNSS receiver, if the parameter <mode> of AT+UGPS
command is set to 0 (default setting)