ELRS Dual-OTA Flasher

Put two ELRS firmwares on one ESP32 at once — app0 = v3.x and app1 = v4.x — and switch between them. Chrome or Edge only.

⚠️ Web Serial isn’t available in this browser. Use Chrome or Edge over https (or http://localhost).

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ESP32 flash map

“On board / active” reflect what you do in this session (and Read active); the tool doesn’t auto-read the chip.

Bootloader 0x1000 —

Partition table 0x8000

NVS settings 0x9000

OTA data 0xe000

app0 · v3.x ACTIVE 0x10000 staged: — on board: —

app1 · v4.x ACTIVE 0x1F0000 staged: — on board: —

SPIFFS / filesystem 0x3D0000

Connect your board

Plug the board in over USB and connect. Hold BOOT while connecting if it won’t sync. Flashing tools unlock once connected.

Baud

“Detect target” reads firmware already on the board and pre-selects it below (won’t work on an empty/stock board).

Configure firmware

Pick a version + your board, set the region and (optionally) a bind phrase. It downloads the matching pre-built firmware and personalises it in your browser (the bind phrase never leaves this page).

Version

Vendor

Type

Device

Region/domain

Bind phrase

Stage into slot

Two slots, kept side by side. Staging v3 into app0 and v4 into app1 does not erase the other — both firmwares live on the board and you choose which one boots (Step 3 → Active slot, or 3 quick power-cycles with the slot-switch bootloader). Stage one slot to keep the other untouched, or stage both to load v3 and v4 together.

Flash to the board

Flash the firmware you staged (from the cloud)

Use these after Step 1.

Install slot-switch bootloader (3 power-cycles switch slots)

Provision both sets up a new/stock board — it writes the bootloader, partition table and both slots (needs both v3 and v4 staged), then boots app0. Update appN replaces just that one version, leaving the other slot, the bootloader and the active-slot choice untouched.

📂 Advanced — flash your own local .bin files

v3.x image (→ app0):

v4.x image (→ app1):

For images you configured yourself with the ELRS Configurator / official web flasher.

📥 Read firmware back from a slot

Downloads the full slot to a .bin (≈1 min each).

Tools

⇄

Slot switcher

Choose which firmware boots. Read active shows the current one.

app0 (v3.x) app1 (v4.x)

⚙

Slot-switch bootloader

Installs a custom second-stage bootloader (to 0x1000 only; app slots untouched). Then 3 quick power-cycles (each off/on within ~2 s) flip the active slot — no computer needed. Normal boots wait ~2 s. 4 MB ESP32 / min_spiffs.

📡

RNode Provision

Three-step process matching rnode-flasher: Provision → Write firmware hash → Configure radio.

Band 433 MHz 868 / 915 MHz