Make builds portable
Packaged the ESP IDF build setup in Docker so the toolchain and its configuration travel together across development environments.
CASE STUDY · 2026
Dual Partition OTA Bootloader.
Update firmware remotely and keep a rollback path ready.
A custom ESP IDF bootloader and flash layout that downloads firmware blocks over WiFi and switches between two application slots for rollback.
01THE PROJECT
OVERVIEW
What it is
and who it helps.
This project adds a custom application bootloader to an ESP32 update flow. A containerized Docker toolchain builds the firmware, a headless Debian server provides remote image blocks over WiFi, and the device uses two application slots so it can switch execution to the alternate image instead of overwriting the only working firmware.
2 slotsIndependent app images
0x9000Partition table offset
WiFi OTARemote firmware delivery
THE CHALLENGE
A remote firmware update has to survive layout mistakes, interrupted transfers, and a newly installed image that cannot boot. The flash partition map and execution pointer must agree exactly, or the device risks writing across a sector boundary or losing its last working application.
HOW I APPROACHED IT
From the first
interaction to the edge cases.
Reserve safe flash regions
Moved the active partition table offset to 0x9000 to avoid sector collisions and defined separate application slots at 0x10000 and 0x1F0000.
Fetch updates from the edge
Built a background deployment path that downloads remote firmware blocks over WiFi from a headless Debian host.
Keep a working boot target
Added explicit execution pointer switching between the two application slots, preserving the alternate image as the rollback destination.
OUTCOME
A remote update with a second chance.
The layout and boot flow provide two explicit application destinations and a remote download path. Execution can move to the alternate slot while the previous application remains available for recovery.
02TOOLS USED
BUILT WITH