Open-Source ESC Firmware: AM32 vs Bluejay Explained

AM32 and Bluejay do the same job on different silicon. The chip on your ESC decides which one you can run, and that matters more than any feature list.

By the FPV Drone Essentials editors · Build · Published October 21, 2026

The "AM32 vs Bluejay" question usually gets framed as a contest. It is not one. Each firmware targets a different family of ESC processor, so the real question is what chip your ESC uses. Once you know that, the choice is mostly made for you. The remaining work is flashing the right version safely.

This column covers four things:

• which firmware runs on which hardware
• what each project's releases page shows
• how to approach a flash without bricking a board
• what the newer open-hardware flight controllers and 4-in-1 ESCs offer builders who want to repair or modify their boards

The short answer: it depends on the chip

AM32 is open firmware for ESCs built on ARM microcontrollers. It started in the AlkaMotors repository as firmware for ESCs using the STM32F051. Older write-ups still describe it as an F051-only project, but that description comes from the legacy repo. Development has moved to the am32-firmware organisation on GitHub, so check the current repository for the up-to-date list of supported processors.

Bluejay is open firmware for the older 8-bit ESCs in the BLHeli_S style, which use EFM8 BB21 or BB51 chips. If your ESC carries one of those 8-bit parts, Bluejay is the open option. If it carries an ARM chip, AM32 is.

The two projects are written for completely different processors. You cannot pick one on preference and flash it onto whatever ESC you own. Identify the MCU first. The ESC listing, the board markings or the existing firmware's target name will tell you.

If you are still fuzzy on where the ESC sits between battery, flight controller and motors, the FPV Drone Components Explained guide lays out each part's job. The Power Chain covers why the ESC takes the hardest electrical punishment on the quad.

Where AM32 stands

When we checked, the AM32 releases page listed version 2.21 as the latest. Releases move, so look at the page yourself before you flash in case something newer is out.

The 2.21 release notes carry one instruction worth taking seriously. If you are coming from an older AM32 version, run 2.21 on default settings rather than carrying your old values across. Write down your current values before you flash, then begin from defaults.

The main tool is the AM32 Configurator. It runs in a web browser and handles both configuration and firmware updates. Older guides point you to the AlkaMotors repo and a tool called Multi_ESC. Treat those as history. The current project and the Configurator are where updates come from.

AM32 also has a bootloader, maintained as its own project with v19.0.0 as the latest release. The README in the older AlkaMotors repo described this sequence:

1. The bootloader goes onto the ESC first.
2. The main firmware can then be loaded with the configuration tools through a Betaflight flight controller.

That README belongs to the legacy repo, so read it as background. For current procedure, follow the am32-firmware documentation and the Configurator.

Where Bluejay stands

Bluejay lives in the bird-sanctuary/bluejay repository. The newest build on its releases page is v0.21.1-RC1, and it is flagged as a pre-release.

A release candidate is a test build. It may be perfectly fine, but it has not been declared stable. For a quad you rely on, look down the releases list for the most recent build that is not marked pre-release. Use that unless you have a specific reason to test the RC.

Release v0.18.1 includes adaptations for EFM8BB51 hardware. That alone does not confirm that every stable build fully covers the BB51. If your ESC uses a BB51, read the notes for the version you plan to flash and confirm your target is covered before you commit.

One fix in the release history is worth knowing about. It improves how the firmware protects motors and ESCs when a motor is stuck, which is a good reason to check that the build you choose includes it.

Bidirectional DShot, RPM filtering and startup tunes

These three features drive much of the interest in open ESC firmware. We have not confirmed, from the projects' own documentation, exactly what each firmware offers for each of them, so this column does not list support either way.

Do not take a forum post's word for it either. Read the README or wiki for the exact AM32 or Bluejay version you intend to flash. Then check the Betaflight documentation for the flight controller side of bidirectional DShot and RPM filtering. Verify both ends before you turn anything on.

The ESC chapter of FPV Drone Essentials covers how the ESC talks to the flight controller, if you want the background before you start changing protocols.

How to flash without bricking a board

The steps below follow from which hardware each project targets. They are a starting checklist, not a substitute for the official procedure: we have not checked them against the AM32 or Bluejay docs, so confirm each step there before you flash.

1. Confirm the MCU. AM32 is written for ARM ESCs and Bluejay for EFM8 BB21 or BB51 ESCs. Matching firmware to hardware is the first check.
2. Confirm the exact target. Read the official docs for how to identify the right build for your ESC, and do not guess from a similar-looking board.
3. Use current tools. For AM32, that means the browser-based AM32 Configurator, not old tools from the legacy repo.
4. Pick a stable build. Skip release candidates on a quad you depend on.
5. Record your settings, then reset. Note what you had, then flash. For AM32 upgrades from an older version, start on defaults as the 2.21 notes advise.
6. Test props-off. Remove the props and spin each motor from the Betaflight Motors tab. Confirm direction and smooth running, and only then put the props back on.

ESC flashing usually happens alongside flight controller updates. If you are doing both, How to Update Betaflight Firmware Without Losing Your Tune covers the FC side. The Installing Betaflight chapter of the book walks through the configurator workflow.

Open hardware: when the board itself is open

Open firmware lets you change what an ESC does. Open hardware lets you see, repair and modify the board itself.

The OpenDrone project from Belgium (GitHub organisation OpenDrone-hw, 29 repositories) publishes FPV designs under the CERN-OHL-S-2.0 open-hardware licence. It sells the boards through its webshop at opendrone.be. If you have a damaged board, a published schematic and layout mean you can trace the fault rather than guess.

The flight controllers run Betaflight on Raspberry Pi RP2354 chips, and the ESCs run AM32.

The OpenFC Lite product page lists a microSD slot for blackbox logging, a switchable 10 V VTX rail and UF2 firmware flashing over USB-C.

On the OpenESC-30x30, each of the four motor channels has a dedicated MCU, gate driver and set of six MOSFETs. The board accepts DShot over the usual 8-pin connector. The 60 A figure is the maker's own claim; we have not seen independent testing of it.

Watch the voltage ratings. Only the 30.5x30.5 mm ESC goes to 8S. The OpenESC-20x20 and the OpenAIO top out at 6S.

Not everything in the lineup is open:

• The motors are OEM parts sold with published bench tests and incoming quality checks, but the motor design is not open.
• The GPS board is still only a plan, with no schematic, layout or chosen GNSS module.

The open parts are the flight controllers, ESCs, receivers and AIO boards.

One naming trap: an unrelated GitHub project called OpenDrone_HW_AIO_FC_F405 pairs an STM32F405 flight controller with EFM8BB21 ESCs. It has nothing to do with OpenDrone-hw, so check the organisation name before you download files.

Which one should you run

Let the hardware decide:

• ARM ESC: use the latest AM32 release through the browser Configurator, starting from defaults if you are upgrading. That was 2.21 when we checked; confirm on the releases page.
• BB21 or BB51 ESC: use the newest stable Bluejay build for your target.

If you want to go further and own a board you can fully inspect and repair, open-hardware boards running AM32 and Betaflight are now available. Just match the voltage rating to your build.

Sources

• GitHub – am32-firmware/AM32 releases
• GitHub – am32-firmware/AM32 README
• GitHub – am32-firmware/AM32-bootloader releases
• GitHub – AlkaMotors/AM32-MultiRotor-ESC-firmware (legacy)
• GitHub – bird-sanctuary/bluejay releases
• GitHub – bird-sanctuary/bluejay v0.18.1
• GitHub – OpenDrone-hw organisation
• GitHub – OpenDrone-hw/OpenDrone-Web
• OpenDrone – OpenFC Lite product page
• GitHub – OpenDrone-hw/OpenESC-30x30
• GitHub – OpenDrone-hw/OpenESC-20x20
• GitHub – OpenDrone-hw/OpenMotor
• GitHub – OpenDrone-hw/OpenGPS
• GitHub – OpenDrone-hw/OpenAIO

Facts checked against the sources above as of October 14, 2026. Drone rules and firmware change; check the current version before you rely on a detail.