LEON-G100 / LEON-G200 - System Integration Manual
GSM.G1-HW-09002-G3
Preliminary
System description
Page 57 of 125
The pin 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.
The “GPS supply enable” function improves the current consumption of the GPS receiver. When GPS
functionality is not required, the wireless module controlled by the application processor can completely switch
off the GPS receiver using AT commands.
GPIO3
is by default configured to provide the “GPS data ready” function (parameter <gpio_mode> of
AT+UGPIOC command set to 4 by default), to detect when the u-blox GPS receiver connected to the wireless
module is ready to send data by the DDC (I
2
C) interface. The pin is set as
Input, to detect the line status, waking up the wireless module from idle mode when the u-blox GPS receiver
is ready to send data by the DDC (I
2
C) interface; this is possible if the parameter <mode> of +UGPS AT
command is set to 1 and the parameter <GPS_IO_configuration> of +UGPRF AT command is set to 16
Tri-state with an internal active pull-down enabled, otherwise (default setting)
The pin must be connected to the data ready output of the u-blox GPS receiver (i.e. the pin TxD1 of the u-blox
GPS receiver) on the application board.
The “GPS data ready” function provides an improvement in the power consumption of the wireless module.
When power saving is enabled in the wireless module by the AT+UPSV command, the module automatically
enters idle-mode whenever possible and when the GPS receiver doesn’t send data by the DDC (I
2
C) interface.
The
GPIO3
pin can be used by the GPS receiver to indicate to the wireless module that it is ready to send data by
the DDC (I
2
C) interface: it is used by the GPS receiver to 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.
GPIO4
is by default configured to provide the “GPS RTC sharing” function (parameter <gpio_mode> of
AT+UGPIOC command set to 5 by default), to provide a synchronization timing signal at the power up of the
u-blox GPS receiver connected to the wireless module. The pin is set as
Output, to provide a synchronization timing 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 must be connected to the synchronization timing input 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 provides 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.
The application circuit for the connection of a LEON-G100-06x / LEON-G200-06S wireless modules (and
subsequent versions) to a u-blox 3.0 V GPS receiver is illustrated in Figure 34 and the suggested components are
listed in Table 19. A pull-down resistor is mounted on the
GPIO2
line to avoid a switch on of the GPS receiver
when the wireless module is switched-off and its digital pins are tri-stated.
The
V_BCKP
supply output of the LEON-G100 / LEON-G200 series wireless module is connected to the
V_BCKP
backup supply input pin of the GPS receiver to provide the supply for the GPS real time clock and backup RAM
when the
VCC
supply of the wireless module is within its operating range and the
VCC
supply of the GPS
receiver is disabled. This enables the u-blox GPS receiver to recover from a power outage with either a hot start
or a warm start (depending on the duration of the GPS
VCC
outage) and to maintain the configuration settings
saved in the backup RAM.
