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The ARK 4IN1 uses AM32_F051_BOOTLOADER_PB4. You can find the latest release here.
Use the latest release of AM32.
Low KV motors swinging large props on higher cell counts (e.g. 6S with 10"+ props) can experience desync events during rapid throttle changes. The root cause is motor coil demagnetization time extending past the BEMF sensing window when current spikes during a fast throttle transient — the ESC temporarily loses rotor position and the motor stutters. Limiting how fast the duty cycle can change keeps the transient current in check and preserves the sensing window.
Option 1 — lower the ramp rate via configurator. As of AM32 v2.19, ramp speed is adjustable in the AM32 Configurator (Config Tool v1.93+). This is sufficient for most high-inertia configurations — lower the ramp rate until desync events stop.
Option 2 — ARK_4IN1_RAMP_F051 firmware. A dedicated build with a much lower ramp ceiling baked into flash. Use this when the configurable ramp rate on standard firmware is still too aggressive, or when you want the cap locked so a configurator session can't override it.
Differences vs standard firmware:
Main loop rate halved (20 kHz → 10 kHz). Side effect: 2× coarser BEMF sampling.
Ramp rate ceiling reduced ~12× at low RPM and ~32× at high RPM.
Uniform ramp across the RPM range (no high/low-RPM split).
Not suitable for systems that need fast throttle tracking (e.g. interceptors, competition acro) — the reduced ramp rate limits mechanical response authority.
When flashing back and forth between the standard ARK_4IN1 and the RAMP firmware, select "Ignore current MCU layout" in the configurator.
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