Q: What are the key considerations for IoT OTA firmware update design and implementation?
Answer
IoT OTA update design must address: (1) Atomic update: use A/B partitions so update failure never bricks the device. (2) Delta updates: send only the diff between old and new firmware (bsdiff + bspatch) to reduce download size by 70-90%. (3) Integrity: use SHA-256 hash or Ed25519 signature before applying. (4) Versioning: store rollback version in OTP or eFuse. (5) Bandwidth efficiency: schedule downloads during off-peak hours (WiFi) or use LPWAN (LoRa) where every byte costs. (6) Progress tracking: report download progress and flash verification progress to the cloud. (7) Recovery: if boot fails 3 times fall back to previous partition. (8) Power failure resilience: design the flash controller so partial writes are detected and rejected. Implement using RAUC (embedded Linux) Mender (any OS) or custom delta-update daemon.
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