LISA-U1 series - System Integration Manual3G.G2-HW-10002-3 Preliminary System descriptionPage 78 of 1251.12 General Purpose Input/Output (GPIO)The LISA-U1 series modules provide 5 pins (GPIO1, GPIO2, GPIO3, GPIO4 and GPIO5) which can be configuredas 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 theparameter 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 aso Output / High, since 10 μs before the start of first Tx slot, until 5 μs after the end of last Tx sloto Output / Low, otherwiseThe pin configured to provide the “GSM Tx burst indication” function can be connected on the applicationboard 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-bloxGPS 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 of AT+UGPIOC command to 3.The “GPS supply enable” mode can be provided only on one pin per time: it is not possible tosimultaneously set the same mode on another pin.The pin configured to provide the “GPS supply enable” function is set aso Output / High, to switch on the u-blox GPS receiver, if the parameter of AT+UGPScommand is set to 1o Output / Low, to switch off the u-blox GPS receiver, if the parameter of AT+UGPScommand is set to 0 (default setting)The pin configured to provide the “GPS supply enable” function must be connected to the active-highenable pin (or the active-low shutdown pin) of the voltage regulator that supplies the u-blox GPS receiver onthe 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 of AT+UGPIOC command to 7 (default setting).The pin configured to provide the “SIM card detection” function is set aso Input with an internal active pull-down enabled, to sense SIM card presenceThe pin must be connected on the application board to SW2 pin of the SIM card holder, which must provide2 pins for the mechanical card presence detection, with a 470 kΩ pull-down resistor. SW1 pin of the SIMcard holder must be connected to V_INT pin of the module, by a 1 kΩ pull-up resistor. Refer to Figure 43and section 1.8 for the detailed application circuit. The GPIO5 signal will be pulled low by the pull-downwhen a SIM card is not inserted in the holder, and will be pulled high by the pull-up when a SIM card ispresent.Network status indication:Each GPIO (GPIO1, GPIO2, GPIO3, GPIO4 or GPIO5) can be configured to indicate network status (i.e. noservice, registered home 2G network, registered home 3G network, registered visitor 2G network, registeredvisitor 3G network, voice or data 2G/3G call enabled), setting the parameter of AT+UGPIOCcommand to 2.None GPIO pin is by default configured to provide the “Network status indication” function.
