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SARA-R4 series - System integration manual
UBX-16029218 - R20
System description
Page 30 of 128
C1-Public
describe the SARA-R4 series modules switch-off sequence started by means
of the AT+CPWROFF command and by means of the
PWR_ON
/
PWR_CTRL
input pin respectively,
allowing storage of current parameter settings in the modul
e’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 series data sheet
) is applied at the
PWR_ON
/
PWR_CTRL
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
/
PWR_CTRL
input pin), and it enters not-powered mode if the
VCC
supply is removed.
VCC
PWR_ON / PWR_CTRL
RESET_N
V_INT
Internal Reset
System State
BB Pads State
Operational
OFF
Tristate / Floating
ON
Operational → Tristate
AT+CPWROFF
sent to the module
OK
replied by the module
VCC can be
removed
Figure 15: SARA-R4 series modules switch-off sequence by means of AT+CPWROFF command
VCC
PWR_ON / PWR_CTRL
RESET_N
V_INT
Internal Reset
System State
BB Pads State
OFF
Tristate / Floating
ON
Operational -> Tristate
Operational
The module starts the
switch-off routine
VCC can be
removed
Figure 16: SARA-R4 series modules switch-off sequence by means of PWR_ON / PWR_CTRL pin
☞
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 series modules normal operations may lead to an unrecoverable faulty state!
☞
The duration of each phase in the SARA-R4 series
modules’
switch-off routines can largely vary
depending on the application / network settings and the concurrent module activities.