User's Manual

SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R18 Advance Information Appendix
Page 188 of 206
A.4.2 System functions interfaces
Module power-on
SARA-G3 and LISA series power-on sequence is initiated in one of the ways summarized in Table 66. For more
details, see section 1.6.1 or to the relative System Integration Manual of the module [7], [8].
SARA-G3 series LISA-C2 series LISA-U1 series LISA-U2 series
Rising edge on the VCC pins to a
valid voltage as module supply
Rising edge on the VCC pins to a
valid voltage as module supply
with PWR_ON pin permanently
low when VCC is applied
Rising edge on the VCC pins to a
valid voltage as module supply
Rising edge on the VCC pins to a
valid voltage as module supply
Low level on the PWR_ON pin
for appropriate time period
Low pulse on the PWR_ON pin
for appropriate time period
Low pulse on the PWR_ON pin
for appropriate time period
Low pulse on the PWR_ON pin
for appropriate time period
Pre-programmed RTC alarm (not
supported by SARA-G300/G310)
Pre-programmed RTC alarm
Pre-programmed RTC alarm
RESET_N input pin released
from the low level
RESET_N input pin released
from the low level
Table 66: Summary of power on events among modules
The same compatible external power-on circuit can be implemented for SARA and LISA modules even if there
are minor differences in the PWR_ON input voltage levels ranges and in the low level time or low pulse time to
switch-on the module, as reported in Table 67 or in the relative datasheet of the module [1], [4], [5], [6].
PWR_ON falling edge (i.e. low pulse) is required for LISA series, but it is not required for SARA. External pull-up
is not needed for LISA-C2 series since internal pull-up is provided.
Module power-off
SARA and LISA modules can all be properly switched off by means of the AT+CPWROFF command.
Additionally, all LISA-U2 modules, except LISA-U200-00S, can be properly switched off by low pulse on the
PWR_ON pin, as reported in Table 67 or in the relative datasheet of the module [6].
Module reset
SARA and LISA modules reset can be performed in the following way:
x By means of the AT+CFUN command, causing an “internal” or “software” reset
An abrupt “external” or “hardware” reset occurs when a low level is applied to the RESET_N pin.
The same compatible external reset circuit can be implemented for SARA and LISA modules even if there are
minor differences in the RESET_N input voltage levels ranges and in the low level time, as reported in Table 67
or in the relative datasheet of the module [1], [4], [5], [6].
Additional precautions are suggested for the RESET_N line of LISA-U series modules, depending on the
application board handling, to satisfy ESD immunity test requirements as described in the LISA-U Series System
Integration Manual [8].
External 32 kHz input and internal 32 kHz output
The EXT32K input and the 32K_OUT output are available only on the SARA-G300 and SARA-G310 modules to
provide the 32 kHz reference clock for the Real Time Clock (RTC) timing, used by the module processor to reach
the low power idle-mode and provide the RTC functions.
SARA-G340, SARA-G350 and LISA-U modules are equipped with internal 32 kHz oscillator to provide the same
functions.
LISA-C2 series do not provide RTC and the relative functions.