u-blox SARA-R4 Series System Integration Manual

Contents

SARA-R4 series - System Integration ManualUBX-16029218 - R06 System descriptionPage 30 of 1021.13.6 HTTPSARA-R4 series modules provide the embedded Hyper-Text Transfer Protocol (HTTP) services via AT commandsfor sending requests to a remote HTTP server, receiving the server response and transparently storing it in themodule’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 thedevice via a special boot loader on the module. The bootloader first authenticates the downloaded image, theninstalls 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 thenext wake-up, and restarts the firmware installation. After completing the upgrade, the module is reset againand 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 saving1.13.9.1 Guidelines to optimize power consumptionThe LTE Cat M1 / NB1 technology is mainly intended for applications requiring a small amount of data exchangeper day (i.e. a few bytes in uplink and downlink per day). Depending on the application type, the battery may berequired to last for a few years. For these reasons, the whole application board should be optimized in terms ofcurrent 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 theAT+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 procedureand store NAS protocol context in non-volatile memory, and then rely on the host application processor forrunning its RTC and triggering wake-up upon need4.4 The use of an external RTC during deep sleep power saving mode is not supported by “00”, “01” and “02” product versions