Ublox SARA-R4 Series - Page 32

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R11 System description Page 32 of 157
⚠ 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.
VCC
PWR_ON
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 10: SARA-R4/N4 series modules switch-off sequence by means of AT+CPWROFF command
VCC
PWR_ON
RESET_N
V_INT
Internal Reset
System State
BB Pads State
OFF
Tristate / Floating
ON
Operational -> Tristate
Operational
0 s
~2.5 s
~5 s
The module starts
the switch-off routine
VCC can be
removed
Figure 11: SARA-R4/N4 series modules switch-off sequence by means of PWR_ON pin