Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 System description Page 24 of 119
1.6.2 Module power-off
SARA-R4/N4 series modules can be cleanly switched off by:
• AT+CPWROFF command (see SARA-R4/N4 series AT Commands Manual [2]).
• Low pulse on the PWR_ON pin for a valid time period (see the SARA-R4/N4 series Data Sheet [1]).
These events listed above trigger the storage of the current parameter settings in the non-volatile memory of the module,
and a clean network detach procedure.
An abrupt under-voltage shutdown occurs on SARA-R4/N4 series modules when the VCC module supply is removed. If
this occurs, it is not possible to perform the storing of the current parameter settings in the module’s non-volatile memory
or to perform the clean network detach.
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☞☞
☞ It is highly recommended to avoid an abrupt removal of the VCC supply during SARA-R4/N4 series modules normal
operations.
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⚠ An abrupt removal of the VCC supply during SARA-R4/N4 series modules normal operations may lead to an
unrecoverable faulty state!
An abrupt hardware shutdown occurs on SARA-R4/N4 series modules when a low level is applied on RESET_N pin. 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.
☞
☞☞
☞ It is highly recommended to avoid an abrupt hardware shutdown of the module by forcing a low level on the RESET_N
input pin during module 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 reply to a specific AT command after a time period longer than the one
defined in 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!
Figure 10 and Figure 11 describe the SARA-R4/N4 series modules switch-off sequence started by means of the
AT+CPWROFF command and by means of the PWR_ON input pin respectively, allowing storage of current parameter
settings in the module’s non-volatile memory and a clean network detach, with the following phases:
• When the +CPWROFF AT command is sent, or when a low pulse with appropriate time duration (see the SARA-R4/N4
series Data Sheet [1]) is applied at the PWR_ON input pin, the module starts the switch-off routine.
• Then, if the +CPWROFF AT command has been sent, the module replies OK on the AT interface: the switch-off routine
is in progress.
• At the end of the switch-off routine, all the digital pins are tri-stated and all the internal voltage regulators are turned
off, including the generic digital interfaces supply (V_INT).
• Then, the module remains in switch-off mode as long as a switch on event does not occur (e.g. applying a low level
to PWR_ON), and enters not-powered mode if the VCC supply is removed.