LEXI-R422 - System integration manual
UBX-23007449 - R02
System description
Page 24 of 108
C1-Public
show the LEXI-R422 modules switch-off sequence started by means of the
AT+CPWROFF command and by the
PWR_CTRL
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 is applied at the
PWR_CTRL
input
pin with appropriate time duration (see the LEXI-R422 data sheet
), 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_CTRL
input pin), and it enters not-powered mode if the
VCC
supply is removed.
VCC
PWR_CTRL
V_INT
Internal Reset
System State
BB Pads State
Operational
OFF
Tristate / Floating
ON
Operational → Tristate
AT+CPWROFF
sent to the module
0 s
~2.5 s
~5 s
OK
replied by the module
VCC can be
removed
Figure 12: LEXI-R422 modules switch-off sequence by means of AT+CPWROFF command
VCC
PWR_CTRL
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 13: LEXI-R422 modules switch-off sequence by means of 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
LEXI-R422 modules normal operations may lead to an unrecoverable faulty state!
☞
The duration of each phase in the LEXI-R422 modules switch-off routines can largely vary
depending on the application / network settings and the concurrent module activities.