SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
Appendix
Page 199 of 217
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 67. 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 67: 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 68 or in the relative data sheet 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 68 or in the relative data sheet of the module [6].
Module reset
SARA and LISA modules reset can be performed in the following way:
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 68
or in the relative data sheet of the module [1], [4], [5], [6].
Additional precautions are suggested for the
RESET_N
line of LISA-U2 series modules, depending on the
application board handling, to satisfy ESD immunity test requirements as described in the
LISA-U Series System
Integration Manual
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-U2 modules are equipped with internal 32 kHz oscillator to provide the same
functions.
LISA-C2 series do not provide RTC and the relative functions.
