SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
System description
Page 42 of 217
1.6.4
External 32 kHz signal input (EXT32K)
The
EXT32K
pin is not available on SARA-G340, SARA-G350 and SARA-U2 series modules.
The
EXT32K
pin of SARA-G300 / SARA-G310 modules is an input pin that must be fed by a proper 32 kHz
signal to make available the reference clock for the Real Time Clock (RTC) timing, used by the module processor
when in the low power idle mode.
SARA-G300 / SARA-G310 modules can enter the low power idle mode only if a proper 32 kHz signal is provided
at the
EXT32K
input pin, with power saving configuration enabled by the AT+UPSV command. In this way the
different current consumption figures can be reached with the
EXT32K
input fed by the
32K_OUT
output or by
a proper external 32 kHz signal (for more details, see section 1.5.1.4 and to “Current consumption” section in
the
SARA-G3 series Data Sheet
[1]).
SARA-G300 / SARA-G310 modules can provide the RTC functions (as RTC timing by AT+CCLK command and
RTC alarm by AT+CALA command) only if a proper 32 kHz signal is provided at the
EXT32K
input pin. The RTC
functions will be available only when the module is switched on if the
EXT32K
input is fed by the
32K_OUT
output, or they will be available also when the module is not powered or switched off if the
EXT32K
input is fed
by a proper external 32 kHz signal.
SARA-G3 series Data Sheet
[1] describes the detailed electrical characteristics of the
EXT32K
input pin.
The 32 kHz reference clock for the RTC timing is automatically generated by the internal oscillator provided on
the SARA-G340, SARA-G350 and SARA-U2 series modules: the same pin (31) is a reserved (
RSVD
) pin internally
not connected, since an external 32 kHz signal is not needed to enter the low power idle mode and to provide
the RTC functions.
1.6.5
Internal 32 kHz signal output (32K_OUT)
The
32K_OUT
pin is not available on SARA-G340, SARA-G350 and SARA-U2 series modules.
The
32K_OUT
pin of SARA-G300 / SARA-G310 modules is an output pin that provides a 32 kHz reference signal
generated by the module, suitable only to feed the
EXT32K
input pin of SARA-G300 / SARA-G310 modules, to
make available the reference clock for the Real Time Clock (RTC) timing, so that the modules can enter the low
power idle mode and can provide the RTC functions with modules switched on.
The
32K_OUT
pin does not provide the 32 kHz output signal when the SARA-G300 / SARA-G310 modules are
in power down mode: the
EXT32K
input pin must be fed by an external proper 32 kHz signal to make available
the RTC functions when the modules are not powered or switched off.
SARA-G340, SARA-G350 and SARA-U2 series modules do not provide the
32K_OUT
output, as there is no
EXT32K
input to feed on the modules: pin 24 constitutes the
GPIO3
on these modules.
