SARA-R42 - Application note
UBX-20050829 - R02
PSM, eDRX and deep-sleep mode
Page 29 of 58
C1-Public
Command
Response
Description
+CSCON: 0
At expiry of inactivity time on the network side, the RRC
connection is released by the eNodeB. Both T3324 and T3412
timers are started with the assigned values.
+UUPSMR: 1,1
or
+UUPSMR: 2,3
+UUPSMR: 1,1
At T3324 expiry the module can enter the PSM deep-sleep
mode directly or with a delay as soon as it has completed any
pending activity. The +UUPSMR URC allows to monitor the
PSM deep-sleep mode entry.
+UUPSMR: 0
At T3412 expiry the module exits the PSM deep-sleep mode to
perform a TAU.
The PSM deep-sleep mode exit can be also anticipated by the
host application through an early wake-up via the PWR_ON pin.
In both cases the PSM deep-sleep mode exit can be monitored
via the +UUPSMR URC.
ATD*99***1#
CONNECT
At exit from PSM, PPP mode shall be locally restored. IP
address will be the same assigned during attach, and uplink
data can be sent to the network without the need to re-
register.
8.2
Deep-sleep mode
In deep-sleep mode, enabled via
AT+CPSMS=1
command, the module keeps running at negligible
current (for definitions and power consumption characterization, see the SARA-R4 series system
integration manual
). The module is in minimum functionality, not responsive to AT commands.
When the host application needs to interact with the module in deep-sleep state, e.g. to use the GNSS
receiver, issue AT commands or to send MO data, it can either wait the module to exit deep-sleep
state autonomously, e.g. at periodic T3412 timer expiry in case of PSM deep-sleep, or trigger an early
wake-up via the PWR_ON pin. From a power consumption point of view the first solution needs to be
preferred, if possible, for GNSS receiver usage and AT commands issuing, whereas the second one
should be used for MO data, waking-up the module just before it exits PSM deep-sleep by itself when
possible.
To keep power consumptions in deep-sleep extremely low the only running module component in this
state is a low power low accuracy clock. Being this clock inaccurate, it can be affected by an always
negative drift, causing the time in deep-sleep to be shortened by no more than 1% of the expected
deep-sleep duration. When exiting deep-sleep the module checks the network time and, eventually,
can immediately re-enter in deep-sleep if convenient from power consumption point-of-view.
When the module enters deep-sleep mode, it locally deactivates MUX and PPP and is not responsive
to AT commands. Any non NVM saved settings are lost. Timers including application timers are reset
except for T3412 and throttling timers: T3402, sever network failure (SNF, Verizon specific), T3346,
T3396, and T3245 (if it is configured in USIM), which are saved and restored at deep-sleep exit. PIN
check should not be used along with deep-sleep since it would prevent cellular connectivity restore at
deep-sleep exit until PIN re-insertion. In case the autonomous wake-up would be scheduled in less
than 1 minute the UE does not enter deep-sleep to compensate for boot penalty.
8.2.1
Deep-sleep aware applications and deep-sleep postponing
Some embedded applications and features can temporarily postpone entrance into deep-sleep mode
until they have completed any pending activity. Activities that can delay deep-sleep mode entry are
LwM2M, GNSS receiver usage and security, which might be waiting for a response from the server, as
well as the AT interface, which restarts a 6 s guard timer any time a character is received over the
UART interface. Deep-sleep aware applications preventing deep-sleep entry can be monitored via the
+UUPSMR:2,<client_id>
URC.
Coverage Extension (CE) modes can be another cause for entering deep-sleep with delay. In extended
coverage the network may release the RRC connection later than in normal coverage to accommodate
