SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R11 System description Page 33 of 157
☞ The Internal Reset signal is not available on a module pin, but it is highly recommended to monitor the
V_INT pin to sense the end of the switch-off sequence.
⚠ VCC supply can be removed only after V_INT goes low: an abrupt removal of the VCC supply during
SARA-R4/N4 series modules normal operations may lead to an unrecoverable faulty state!
☞ The duration of each phase in the SARA-R4/N4 series modules’ switch-off routines can largely vary
depending on the application / network settings and the concurrent module activities.
1.6.3 Module reset
SARA-R4/N4 series modules can be cleanly reset (rebooted) by:
AT+CFUN command (see the SARA-R4/N4 series AT Commands Manual [2]).
In the case above an “internal” or “software” reset of the module is executed: the current parameter settings
are saved in the module’s non-volatile memory and a clean network detach is performed.
An abrupt hardware shutdown occurs on SARA-R4/N4 series modules when a low level is applied on
RESET_N input pin for a valid time period. In this case, the current parameter settings are not saved in the
module’s non-volatile memory and a clean network detach is not performed. Then, the module remains in
power-off mode as long as a switch on event does not occur applying an appropriate low level to the
PWR_ON input.
☞ It is highly recommended to avoid an abrupt hardware shutdown of the module by forcing a low level
on the RESET_N input during modules normal operation: the RESET_N line should be set low only if
reset or shutdown via AT commands fails or if the module does not provide a reply to a specific AT
command after a time period longer than the one defined in the SARA-R4/N4 series AT Commands
Manual [2].
⚠ Forcing a low level on the RESET_N input during SARA-R4/N4 series modules normal operations may
lead to an unrecoverable faulty state!
The RESET_N input pin is directly connected to the Power Management Unit IC, with an integrated pull-up
to a 1.8 V supply domain, in order to perform an abrupt hardware shutdown when asserted. Detailed
electrical characteristics with voltages and timings are described in the SARA-R4/N4 series Data Sheet [1].
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