AM32 ESC Firmware – An Open Source Alternative to BLHeli32

by Oscar
Neutronrc At32f435 Am32 Aio Flight Controller Fc Esc Board Top

If the term AM32 has caught your attention recently, you’ve landed in the right place. In this article, we’ll dive deep into the world of AM32 ESC firmware – understanding its core features, unique advantages, and how you can leverage its power for your next FPV drone build.

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But first, let’s quickly brush up on our basics. An Electronic Speed Controller (ESC) is a device used in the RC hobby to control the speed of your motors. To do this, every ESC must be loaded with a piece of software – the ESC firmware. Amongst the software available for 32-bit ESCs, BLHeli_32 has long reigned supreme. But there’s a new kid on the block – AM32. Let’s get to know it a bit better, shall we?

Understanding the Constraints of BLHeli_32

For years, BLHeli_32 has been a staple in the FPV community, favoured for its reliability, efficiency, and rich feature set. But, like any technology, it has its challenges. Despite working fairly well, there’s a sense that it doesn’t tap into the full potential of what’s possible with ESCs.

The primary concern with BLHeli_32 is its closed-source nature. The firmware code is not accessible to the public for tinkering or improvements.

And it doesn’t stop there. For ESC manufacturers, there’s a price tag attached to using BLHeli_32 – a cost typically passed down to us, the consumers.

Enters the AM32 Firmware

This brings us to the AM32 firmware – an exciting development in the drone community. AM32 is an open-source ESC firmware, designed with modern ARM-based ESCs in mind.

What’s great about AM32 is that it doesn’t just trying to match BLHeli_32; in several aspects, it outshines it, such as efficiency and torque generation. This makes AM32 a viable and attractive alternative to the BLHeli_32 ESC. And there’s an added bonus: ESC manufacturers aren’t required to pay for licensing. Consequently, AM32-equipped ESCs can be more cost-effective.

Now, if you’re curious about what AM32 brings to the table, here are some of its compelling features, straight from its official description:

  • Open Source firmware
  • Firmware upgradable via betaflight passthrough (only support G4, F4 and F7 FCs, and make sure your betaflight
  • firmware is up to date when you try to use passthrough)
  • Servo PWM, DShot300, DShot600 ESC protocol support
  • Bi-directional Dshot
  • KISS standard ESC telemetry
  • Variable PWM frequency
  • Sinusoidal startup mode, which is designed to get larger motors up to speed
  • Stuck motor protection

A Word of Caution

Before you dash off to download the AM32 ESC firmware, I feel it’s only fair to offer a word of caution. Remember, this is open-source software. On the one hand, that’s a brilliant thing because it’s continually being refined and improved. On the other hand, it’s a relatively new firmware that you might encounter bugs and issues that are still being worked through.

If the prospect of troubleshooting and problem-solving leaves you a little uneasy, you might be better off sticking with the tried-and-true BLHeli32 ESC for the time being.

Hardware Compatibility

In terms of hardware compatibility, AM32 currently supports several MCUs including the STSPIN32F0, STM32F051, STM32G071, GD32E230, AT32F415, and AT32F421. It’s pretty versatile, which is yet another feather in its cap.

For a complete list of supported ESCs, I recommend taking a look at this link:

If your current ESC is on that list, you’re good to go! If not, don’t fret. Remember, this is an open-source project, which means new hardware is being added to the compatibility list all the time.

How to Flash AM32

If you’ve decided to give AM32 a try, there’s some good news. Some new ESCs are available on the market with AM32 firmware pre-installed! You can find them here: In this case, you won’t need to do any firmware flashing at all.

Neutronrc At32f435 Am32 Aio Flight Controller Fc Esc Board Bottom

To configure settings or update the AM32 firmware, you can use the ESC-Configurator tool: This tool is the same one used for flashing Bluejay firmware, in case you’re familiar with that.

Want to try AM32 on your existing 32-bit ESC? You certainly can. AM32 firmware is compatible with many BLHeli32 ESCs. But first, you will need to install the AM32 bootloader using an ST-Link V2 programming adapter. You can purchase the ST-Link V2 Tool from:

Stm32 St Link V2 Program Usb Tool Pinout 3.3v 5v Dio Clk

But beware: flashing AM32 to BLHeli_32 ESC will erase the MCU memory, and it’s irreversible. This means that once you make the switch to AM32, you won’t be able to revert back to BLHeli_32.

Now, when installing the bootloader, it’s crucial to match it to the MCU type and signal input pin of the ESC. The compatibility chart lists the bootloader pinouts. You can find the current bootloaders here:

If you need to update an existing AM32 bootloader, you can find an update tool here:

Once the bootloader is installed, you can install the main firmware either using the configuration tools and a Betaflight flight controller (via Betaflight Passthrough) or a direct connection with a USB serial adapter modified for one wire.

To flash or configure AM32 firmnware, you can use the online ESC-Configurator tool:

The latest release of the firmware can be found here:

Wrapping Up

So, there you have it. AM32 is not just a great alternative to BLHeli32 ESC; it has the potential to become a game-changer in our hobby. By driving down ESC prices and fostering competition, it’s sure to spur innovation.

Personally, I’m always excited to see new open-source initiatives like AM32. They truly put the power in the hands of the user, providing us with the flexibility and freedom to explore and optimize our systems.

However, a final reminder if you’re considering this move: once you transition your existing BLHeli_32 ESC to AM32, there’s no turning back. So weigh your options carefully, and make sure you’re ready for this commitment.

Regardless of the path you choose, I hope this overview has helped you understand AM32 a little better. Here’s to enjoying the ride as we continue to explore new frontiers in this exciting hobby!

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Marcy 27th October 2023 - 10:43 am

Buongiorno, desideravo chiedere una informazione tecnica, ho acquistato un esc flycolor francy 2 da 50A, vorrei cambiare il firmware da blheli32 a am32, per poterlo fare devo caricare un nuovo bootloader tramite st-link v2, la mia domanda è nel circuito dell’esc quali sono i pin swc e swd, desidero sapere anche se non è facile però spero voi potreste aiutarmi chiedendo qualche informazione? grazie

hamlet 11th October 2023 - 5:07 am

is there any boot-loader available for AT32F435 (I found one for AT32F421 from Alka motors – github). >?

Marek 19th August 2023 - 10:33 am

Can you please write an article about AM32 settings and options?

A Reader 29th July 2023 - 10:07 am

This line suggests that the closed source software does not contain bugs. That’s not a fair comparison. If the reader is less experienced with software they may conflate this with open source is bad. The truth is the same types of people are making both, just that some are not sharing their work openly, not accepting community contributions, and charging for their work. Both can have amazing developers. Often open source developers have other jobs which is why they don’t feel the need to charge for their work.