u-blox SARA-R4 Series, System Integration Manual

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SARA-R4 series - System Integration Manual
UBX-16029218 - R06 System description
Page 30 of 102
1.13.6 HTTP
SARA-R4 series modules provide the embedded Hyper-Text Transfer Protocol (HTTP) services via AT commands
for sending requests to a remote HTTP server, receiving the server response and transparently storing it in the
module’s Flash File System (FFS).
For more details about embedded HTTP functionalities see the
SARA-R4 series AT Commands Manual [2].
1.13.7 Firmware update Over AT (FOAT)
This feature allows upgrading of the module firmware over the AT interface, using AT commands.
The +UFWUPD AT command enables a code download to the device from the host via the Xmodem protocol.
The +UFWINSTALL AT command then triggers a reboot, and upon reboot initiates a firmware installation on the
device via a special boot loader on the module. The bootloader first authenticates the downloaded image, then
installs it, and then reboots the module.
Firmware authenticity verification is performed via a security signature. The firmware is then installed,
overwriting the current version. In case of power loss during this phase, the boot loader detects a fault at the
next wake-up, and restarts the firmware installation. After completing the upgrade, the module is reset again
and wakes-up in normal boot.
For more details about Firmware update Over AT procedure, see the
SARA-R4 series AT Commands Manual [2],
+UFWUPD AT command.
1.13.8 Firmware update Over The Air (uFOTA)
This feature allows upgrading the module firmware over the air interface, based on u-blox client/server solution
(uFOTA), using LWM2M.
For more details about Firmware update Over The Air procedure see
SARA-R4 series AT Commands Manual [2].
1.13.9 Power saving
1.13.9.1 Guidelines to optimize power consumption
The LTE Cat M1 / NB1 technology is mainly intended for applications requiring a small amount of data exchange
per day (i.e. a few bytes in uplink and downlink per day). Depending on the application type, the battery may be
required to last for a few years. For these reasons, the whole application board should be optimized in terms of
current consumption and should carefully take into account the following aspects:

Enable the power saving configuration using the AT+CPSMS command (for the complete description of the
AT+CPSMS command, see the
SARA-R4 series AT Commands Manual [2]).

Minimize current leakage on the power supply line.

Optimize the antenna matching, since an un-matched antenna leads to higher current consumption.

Use an application processor with UART interface working at the same voltage level (1.8 V) as the module.
In this way it is possible to avoid voltage translators, which helps to minimize current leakage.

Monitor
V_INT
level to sense when the module enters power-off mode or deep sleep power saving mode.

Disconnect the VCC supply source from the module when it is switched off (see 2.2.1.8).

Disconnect the VCC supply source from the module during deep sleep power saving mode (see 2.2.1.8):
using a host application processor equipped with a RTC, the module can execute a standard PSM procedure
and store NAS protocol context in non-volatile memory, and then rely on the host application processor for
running its RTC and triggering wake-up upon need
4
.
4 The use of an external RTC during deep sleep power saving mode is not supported by “00”, “01” and “02” product versions