Firmware
What is an OTA update?
Over-the-Air Update
An over-the-air (OTA) update delivers new firmware to a deployed device remotely over its network, letting manufacturers fix bugs and add features.
Secure OTA — with signed images, rollback protection, and dual-bank storage — is now a baseline expectation for connected products and a requirement under emerging IoT security regulations.
How OTA updates work
The device downloads a new firmware image over its network link, verifies its integrity and signature, writes it to a second flash slot, and a bootloader swaps to the new image on reboot. If the new image fails its self-test, the bootloader rolls back to the previous one.
What makes OTA secure and reliable
Sign images and verify them in the bootloader (secure boot), encrypt images in transit, reserve flash for A/B slots or a swap area, handle power loss mid-update, prevent downgrade to vulnerable versions, and stage rollouts to a small group of devices first. MCUboot, Mender, SWUpdate and vendor services such as AWS IoT and Azure Device Update are common building blocks.
Why OTA is now expected
Regulations such as the EU Cyber Resilience Act expect connected products to receive security updates for their support period, so OTA is increasingly a design requirement rather than an extra.
OTA Update FAQ
- What does OTA mean?
- OTA means over-the-air: delivering a firmware or software update to a device through its wireless or network connection.
- How much extra flash does OTA need?
- A dual-slot (A/B) scheme needs roughly twice the application size plus the bootloader; delta updates and compression can reduce download size but not the need for a safe fallback image.