LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 100 of 183
C1-Public
The pin configured to provide the “GNSS supply enable” function must be connected to the active
-
high enable pin (or the active-low shutdown pin) of the voltage regulator that supplies the u-blox GNSS
receiver on the application board.
GNSS data ready:
Only the
GPIO3
pin provides the “GNSS data ready” function, to sense when a u
-blox GNSS receiver
connected to the cellular module is ready to send data via the DDC (I2C) interface, setting the
parameter <gpio_mode> of AT+UGPIOC command to 4.
The pin c
onfigured to provide the “GNSS data ready” function will be set as
•
Input, to sense the line status, waking up the cellular module from idle mode when the u-blox GNSS
receiver is ready to send data via the DDC (I2C) interface; this is possible if the parameter <mode>
of AT+UGPS command is set to 1 and the parameter <GPS_IO_configuration> of AT+UGPRF
command is set to 16
•
Tri-state with an internal active pull-down enabled, otherwise (default setting)
The pin that provides the “GNSS data ready” function must b
e connected to the data ready output of
the u-blox GNSS receiver (i.e. the pin TxD1 of the u-blox GNSS receiver) on the application board.
GNSS RTC sharing:
Only the
GPIO4
pin provides the “GNSS RTC sharing” function to provide an RTC (Real Time Clock)
synchronization signal to the u-blox GNSS receiver connected to the cellular module, setting the
parameter <gpio_mode> of AT+UGPIOC command to 5.
The pin configured to provid
e the “GNSS RTC sharing” function will be set as
•
Output, to provide an RTC (Real Time Clock) synchronization signal to the u-blox GNSS receiver if
the parameter <mode> of AT+UGPS command is set to 1 and parameter <GPS_IO_configuration>
of AT+UGPRF command is set to 32
•
Output / Low, otherwise (default setting)
The pin that provides the “GNSS RTC sharing” function must be connected to the RTC
synchronization input of the u-blox GNSS receiver (i.e. the pin EXTINT0 of the u-blox GNSS receiver)
on the application board.
SIM card detection:
The
GPIO5
pin is by default configured by AT+UGPIOC command to detect SIM card presence.
Only the
GPIO5
pin can be configured to provide the “SIM card detection” function, setting the
parameter <gpio_mode> of the AT+UGPIOC command to 7 (default setting).
The pin configured to provide the “SIM card detection” function is set as
•
Input with an internal active pull-down enabled, to sense SIM card presence
The pin must be connected on the application board to SW2 pin of the SIM card holder, which must
provide 2 pins for the mechanical card presence detection, with a 470 k
Ω
pull-down resistor. SW1 pin
of the SIM card holder must be connected to the
V_INT
pin of the module, by a 1 k
Ω
pull-up resistor.
for the application circuit. The
GPIO5
signal will be pulled low by the pull-
down when a SIM card is not inserted in the holder, and will be pulled high by the pull-up when a SIM
card is present.
The
GPIO5
pin is configured as an external interrupt to detect SIM card presence. An Unsolicited
Result Code (URC) can be generated each time that there is a change of status (for more details, see
the “simind” value of the <descr> parameter of +CIND and +CMER commands in the u
-blox AT
