SARA-R42 - Application note
UBX-20050829 - R02
Application design and development
Page 10 of 58
C1-Public
Similar considerations hold for the security client.
Power saving features (+UPSV, PSM, eDRX) shall be configured based on the target power
consumption profile, based on the suggestions in section
) to be used depends on the type of application and SIM card (regional or
global roaming). If the SIM card belongs to an MNO for which the module has gained the type approval,
the MNO profile is available in the FW and shall be used. For more details about this, see the SARA-R4
series data sheet
Debuggability can be provided via test endpoints, access to the USB interface, and in general a prolific
application log containing all AT command strings exchanged with the module and diagnostic
information sent by the module with timing information. Monitoring the module status is a
requirement to implement recovery procedures via HW or SW, as described in section
☞
To evaluate the disabling of the LwM2M client, especially in the scenarios in which the related
features are not explicitly required by the MNO and not needed by the user.
3.2
Application stages
3.2.1
Persistent configurations
Some module settings are persistent, that is, they are stored in the module Non-Volatile Memory
(NVM). Among these are the MNO profile (see section
), APN for Internet connectivity, and active
LTE bands.
The host application should implement a persistent configuration setting phase, performed once and
then at an as-needed basis, where all AT commands related to the required settings are issued.
☞
See the SARA-R4 FW update application note
for persistence of settings after a FW update. If
settings are not retained, they shall be reapplied as per section
3.2.2
Power on/boot/PSM exit
In general at each boot, the application should read configurations and make sure they are correct. If
not, persistent configurations can be reapplied.
Not all the module configurations are persistent. Therefore, the application, after each module boot,
should again set these volatile configurations (for example,
AT+CMEE=2
, URC enabling).
It is very important that the application has a robust mechanism to detect when the module is ready
to communicate via AT commands at the power-on: a solution is to enable the greeting message
(
+CSGT
AT command); alternatively, the host application can wait for a response to
“
AT
”
command.
The application should configure module time. Automatic update of local time with the network time
information is the factory setting (
+CTZU: 1
), so after LTE attach, the time of the module is generally
updated.
☞
When using PSM, at exit from low power mode, the volatile settings as well as the current
communication port mode (MUX, dialup) shall be restored too.
3.2.3
Network registration
For details about the network registration stage, see section
3.2.4
IP acquisition
For some details and guidelines on this topic, see the Internet applications development guide
application note
