LISA-U1 series - System Integration Manual
3G.G2-HW-10002-3
Preliminary
System description
Page 78 of 125
1.12
General Purpose Input/Output (GPIO)
The LISA-U1 series modules provide 5 pins (
GPIO1
,
GPIO2
,
GPIO3
,
GPIO4
and
GPIO5
) 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 refer to
u-blox AT Commands Manual
[2], +UGPIOC, +UGPIOR, +UGPIOW, +UGPS, +UGPRF).
The following functions are available in the LISA-U1 series 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.
None GPIO pin is by default configured to provide the “GSM Tx burst indication” function.
The pin configured to provide the “GSM Tx burst indication” function is set as
o
Output / High, since 10 µs before the start of first Tx slot, until 5 µs after the end of last Tx slot
o
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.
GPS supply enable
:
The
GPIO2
is by default configured by AT+UGPIOC command to enable or disable the supply of the u-blox
GPS receiver connected to the wireless module.
The
GPIO1
,
GPIO3
,
GPIO4
or
GPIO5
pins can be configured to provide the “GPS supply enable” function,
alternatively to the default
GPIO2
pin, setting the parameter <gpio_mode> of AT+UGPIOC command to 3.
The “GPS supply enable” mode can be provided only on one pin per time: it is not possible to
simultaneously set the same mode on another pin.
The pin configured to provide the “GPS supply enable” function is set as
o
Output / High, to switch on the u-blox GPS receiver, if the parameter <mode> of AT+UGPS
command is set to 1
o
Output / Low, to switch off the u-blox GPS receiver, if the parameter <mode> of AT+UGPS
command is set to 0 (default setting)
The pin configured to provide the “GPS 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 GPS 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 AT+UGPIOC command to 7 (default setting).
The pin configured to provide the “SIM card detection” function is set as
o
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
V_INT
pin of the module, by a 1 k
Ω
pull-up resistor. Refer to Figure 43
and section 1.8 for the detailed 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.
Network status indication
:
Each GPIO (
GPIO1
,
GPIO2
,
GPIO3
,
GPIO4
or
GPIO5
) can be configured to indicate network status (i.e. no
service, registered home 2G network, registered home 3G network, registered visitor 2G network, registered
visitor 3G network, voice or data 2G/3G call enabled), setting the parameter <gpio_mode> of AT+UGPIOC
command to 2.
None GPIO pin is by default configured to provide the “Network status indication” function.
