Ublox SARA-N2 Series, Руководство по системной интеграции

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SARA-N2 / N3 series - System integration manual
UBX-17005143 - R13 System description Page 20 of 95
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1.6.2 Module power-off
The SARA-N2 series modules enter the non-powered mode by removing the VCC supply.
The switch-off routine of the SARA-N3 series modules can be properly triggered, with storage of
current parameter settings in the module’s non -volatile memory and clean network detach, by:
• AT+CPWROFF command (see the SARA-N2 / SARA-N3 series AT commands manual [4] ).
• Low level on the PWR_ON input pin, i.e. forcing the pin (normally high due to internal pull-up) to a
low level for a valid time period (see SARA-N3 series data sheet [2] ).
An abrupt under-voltage shutdown occurs on the SARA-N3 series modules when the VCC supply
drops below the extended operating range minimum limit (see the SARA-N3 series data sheet [2] ),
but in this case it is not possible to perform the storing of the current parameter settings in the
module’s non -volatile memory as well as a clean network detach.
Figure 10 shows the switch-off sequence of the SARA-N3 series modules started by means of the
AT+CPWROFF command, 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, the module starts the switch-off routine.
• Then, the module replies OK on the AT interface: the switch-off routine is in progress.
•
At the end of the switch-off routine, the internal voltage regulator generating the V_INT supply rail
is turned off.
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.
VCC
PWR_ON
RESET_N
V_INT
System state
OFF ON
AT+CPWROFF
sent to the module
OK
replied by the module
VCC can be
removed
Figure 10: SARA-N3 series modules switch-off sequence by means of AT+CPWROFF command
☞
It is highly recommended to monitor the V_INT pin to sense the end of the switch-off sequence.
☞
It is highly recommended to avoid an abrupt removal of the VCC supply during module normal
operations: the VCC supply can be removed only when the V_INT rail is switched off by the module.
☞
The duration of each phase in the SARA- N3 series modules’ switch-off routines can largely vary
depending on the application / network settings and the concurrent module activities.