Tech@Carnot
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Tech@Carnot

Everything about Firmware Over The Air Update

The most powerful OTA in human history
Life without FOTA

Benefits of FOTA in manufacturer’s perspective:

  1. Manufacturer gains the ability to remain compliant with evolving industry standards. This expands product lifetime.
  2. It helps to reduce warranty/recall costs by reducing/eliminating service center visits or help desk calls for vehicles or IoT devices. It reduces costs, and complexity by executing new updates quickly.
  3. With the ability to resolve issues remotely, techie doesn’t have to waste valuable time traveling on-site to fix bugs or other problems.
  4. It offers the advantage of speed by shortening the length of time it takes to upgrade installations as you can upgrade multiple devices at the same time.

Well, the first question would come to your mind: how and from where do you start building the OTA mechanism?

Blocks of FOTA Mechanism :

Block Diagram of Firmware Over The Air Update
  1. OTA flow
  2. Bootloader development cost and time
  3. Memory issue
  4. Peripheral access issue
  • Button press
  • Software jump
  • Condition check on reset
CRC16 Calculation
  • You can’t fix the issue using over the air update if the device is not connected to the internet due to software fault. We won’t be able to do any other progress until this is fixed.
  • Bricking a fleet of devices with a bad firmware update is much more possible, and a drastically worse situation to find yourself in.
  • Most important is to test the firmware in all possible situations locally before doing global OTA. So, the above two-issue would be less likely to happen.
  • Keeping track and making sure that firmware rollout goes smoothly can be a major challenge.
  • We have to make sure that, size of the latest firmware should be enough to be fit in storage, or in case of dual bank flash memory, the size of firmware should not be more than half of the total internal memory of the device.

FOTA at Carnot

  1. Target Controller downloads and the host controller updates the target controller’s firmware
  1. Backup FOTA
  2. Factory Reset
FOTA Recovery Options
  • Loop FOTA test:
    In this test, we keep a device standalone and send firmware updates in a loop. On every update, the system downloads, flashes and jumps to the new firmware. Once it is in the application, it again gets a Firmware update request and the cycle continues. We monitor that device for ~300 FOTA, to check whether it is successful on every attempt.
  • System reset:
    In this test, we forcefully reset the system number of times during various processes of FOTA to check whether it is still able to complete FOTA.
  • Invalid file test:
    Forcefully we send some parameters wrong to check our error handling working.

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