AM32 configurator: every AM32 setting and firmware update

AM32 is firmware for 32-bit ARM brushless ESCs. It runs on several microcontroller families, including STM32F051, STM32G071, Artery AT32F421 and GigaDevice GD32E230, and it is the main alternative to BLHeli_32 on 32-bit hardware. Many ESCs ship with it, and many earlier BLHeli_32 boards can be converted by installing an AM32 bootloader.

AM32 releases are built per hardware target. A target name like FLYCOLOR_F051 or WRAITH32_F421 describes the board design and ends with the chip family. The target often does not match the brand on the box, which is why reading it from the ESC is safer than guessing from a product listing.

AM32 has a bootloader that understands the same 4-way passthrough as BLHeli. When you open the ESC configurator, FlySpark asks your Betaflight or INAV flight controller to enter passthrough and connects to each motor output in turn. For each ESC it reads the chip signature, the signal pin the bootloader uses, the 192-byte AM32 settings block and the target name stored just before it.

The settings block lives at the end of flash, and its address depends on the chip. FlySpark knows it for the STM32F051 family and for the 64 KB G071, AT32F421 and GD32 class. If an AM32 ESC reports another chip, FlySpark shows the chip code and says the settings location is unknown instead of guessing.

Timing advance runs from 0 to 30 degrees. Higher timing suits high-KV motors but runs hotter. ESCs flashed with old AM32 releases that stored timing in four steps (0, 7.5, 15 and 22.5 degrees) are shown with those four choices. Startup power runs from 50 to 150 percent; raise it only if motors stutter when starting. Motor KV and motor poles are used for the startup ramp and RPM limits, and most 5-inch motors have 14 poles.

Complementary PWM is active freewheeling, best left on unless the ESC maker says otherwise. Variable PWM frequency raises the PWM frequency with RPM; with it off, the fixed PWM frequency setting (24 to 48 kHz) is used. Sinusoidal startup gives a smooth, quiet start at very low throttle; sine mode range sets the throttle point where it hands over to normal running, and sine mode power sets its strength from 1 to 10.

Brake on stop holds the motor when the throttle is at zero, with brake strength from 1 to 10. Running brake brakes while the throttle drops; 10 means off. Stuck rotor protection cuts power when a motor is blocked. Stall protection is meant for crawlers and slow props, so keep it off on quads. The temperature limit reduces power above 70 to 140 °C (the top value means off), and the current limit needs a current sensor on the ESC. Low voltage cutoff turns on a per-cell cutoff voltage, settable from 2.50 to 3.50 V.

Input protocol Auto lets AM32 detect the signal itself; you can instead fix it to DShot, Servo PWM, Serial or EDT ARM. Beep volume runs from 0 to 11. Telemetry every interval sends ESC telemetry continuously instead of only when asked.

In the Firmware card, Download firmware lists recent AM32 releases for the targets on your quad. FlySpark downloads the file for each target, checks that the chip suffix matches, and flashes every matching ESC. The AM32 bootloader in the first 4 KB of flash is never written, so an interrupted update can be retried.

Before writing, FlySpark marks the settings so that a half-finished flash is visible, then writes and verifies the firmware, then puts your settings back with the version cleared. The ESC tile reads AM32 · power-cycle to finish until you unplug and replug the battery; AM32 then writes its new version number on its first start. If you choose a .hex yourself, a file for another target on the same chip can be flashed with Flash anyway; a file for another chip never is.

A blank ESC, or one that still runs BLHeli_32, has no AM32 bootloader. Installing that bootloader needs a debug probe such as an ST-Link or AT-Link wired to the ESC's programming pads, and the AM32 project documents it per chip. FlySpark cannot install bootloaders. Once the bootloader is on, FlySpark can flash and configure the ESC through the flight controller.