OTA via device shadow

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mongoose-os-libs/ota-shadow    

Overview

This library provides a way to update firmware Over-The-Air via the device shadow mechanism.

In the text below, AWS IoT Shadow will be used.

It works by observing the ota.url entry in the device shadow. That entry must be an URL with the valid Mongoose OS firmware, which is a .zip file. When that entry is changed, this library downloads a firmware from that URL and kicks off an OTA update. The sequence of actions is as follows:

  • Receive shadow delta for ota.url - a new ota.url value
  • Compare ota.url with file on flash. If it is the same as new value, stop
  • If it is different, save new ota.url locally on flash
  • Report new ota_url
  • Trigger an OTA by downloading the .zip
  • During the process, report numeric ota.code and string ota.message entries which indicates the status of the OTA in nearly real time
  • On any failure, stop with the failure ota.message
  • On success, reboot to the new firmware
  • After reboot, commit the new firmware after the successful AWS IoT handshake
  • If AWS IoT handshake does not happen during 5 minutes (the default commit timeout), rollback to the old firmare
  • OTA failure keeps the ota.url delta uncleared

How to trigger an OTA firmware update

Build and flash the https://github.com/mongoose-os-apps/demo-js app, start the console, and provision to AWS IoT. Open the shadow GUI for the device.

Upload built firmware to the Mongoose OS dashboard and copy the firmware URL.

Change the desired shadow state by adding a section ota with url key:

{
  "desired": {
    "ota": {
      "url": "https://mongoose-os.com/dashboard/ota/PATH/TO/APP.zip"
    },
    ...
  },
  ...
}

You can edit device shadow from the AWS IoT dashboard:

When it successfully finishes, it reboots and commits the firmware after the AWS IoT handshake:


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