BLHeli_32 vs AM32 — melody support compared
Both are 32-bit firmwares with bigger melody slots than BLHeli_S, but they differ in subtle ways. Quick comparison from a music-pilot's perspective.
If your ESCs aren't on a SiLabs MCU (so Bluejay isn't an option), you're probably on BLHeli_32 or AM32. Both support startup melodies. Both give you more headroom than BLHeli_S. They're not identical, though, and the differences matter for music playback.
Slot size
- BLHeli_32 — varies by firmware version, but typically 64 bytes per ESC (~30 notes).
- AM32 — 128 bytes per ESC (~62 notes), same as Bluejay.
If your priority is fitting longer songs, AM32 wins handily. BLHeli_32's half-size slot puts you between BLHeli_S (~14 notes) and the modern firmwares (~62), which is enough for a longer hook but not a whole tune.
RTTTL parsing
Both accept standard RTTTL strings via their configurators. Both lowercase note letters and strip whitespace. Neither distinguishes itself in parser leniency.
One quirk: AM32's parser handles dotted notation in either order (8c. or 8.c). BLHeli_32 only accepts the post-note dot (8c.). The converter outputs post-note dotted notation by default, so this rarely matters in practice.
Playback quality
Subjectively, on identical hardware:
- AM32 sounds closer to Bluejay — clean attacks, stable pitch, consistent loudness.
- BLHeli_32 is slightly muddier. Notes have a small attack click. Pitch drifts a bit between fresh and tired batteries (similar issue to BLHeli_S, less pronounced).
This is at the level of "you'd notice in a side-by-side comparison" rather than "this sounds bad". For most pilots either is fine.
Volume
About the same. Both drive the motor at roughly the same PWM amplitude during tones. AM32 is maybe 1 dB louder if you pick the right release version, but it's within experimental error.
Configurator support
- AM32: AM32 Configurator. Web-based via esc-configurator.com, also a desktop build. Melody editor is straightforward.
- BLHeli_32: BLHeli_32 Suite. Desktop only. Melody field is buried in the advanced settings tab. Once you find it, works fine.
Flashing between them
If you bought ESCs that came with BLHeli_32 stock, you can usually re-flash to AM32 if you want. The reverse (AM32 → BLHeli_32) is rarely worth it.
The flash process for both is straightforward via the respective configurator. Both survive reboots and don't require re-flashing for melody changes (the melody is in a separate slot from the firmware).
My recommendation
If your ESCs support both — go AM32. Larger melody slot, cleaner playback, open source, actively maintained, web configurator works on any OS.
If you're stuck on BLHeli_32 because your manufacturer doesn't support flashing AM32, you can still do interesting things with 30 notes. Pick punchy hooks (Imperial March, Mission: Impossible, Star Wars opening) that don't need length. Avoid pop choruses that need to develop.
The converter lets you cap the per-output note count via the "Max notes / output" setting. Set it to 30 for BLHeli_32 instead of the default 62, and you'll get safe-to-flash output.
Side-by-side summary
| BLHeli_32 | AM32 | |
|---|---|---|
| Melody slot | ~64 bytes (≈30 notes) | 128 bytes (≈62 notes) |
| Playback quality | slight attack click, mild voltage drift | clean, Bluejay-like |
| Dotted-note parsing | post-note dot only (8c.) | either order |
| Configurator | BLHeli_32 Suite (desktop only) | web + desktop |
| Licence | closed source, development ended | open source, active |
| Loudness | baseline | ≈ +1 dB, within error |
One row of that table deserves emphasis: BLHeli_32 development has ended. There will be no more releases, and new ESC designs have moved on to AM32. That doesn't make existing BLHeli_32 hardware bad — it flies fine — but if melody features matter and you're choosing between the two on a fresh build, the direction of travel is one-way.
The 30-note reality check
What actually fits in BLHeli_32's smaller slot? From the song library, these arrangements come in under 30 notes per track and flash without trimming:
- Tetris — lead is 19 notes, bass 8.
- Nokia / Gran Vals — 13 notes. Practically free.
- The Imperial March — 24 per voice. The whole three-voice arrangement fits.
- Happy Birthday — 25 notes.
- Also sprach Zarathustra — 12-note fanfare, 20-note timpani part.
What doesn't fit: Für Elise (40 notes) and anything with long running passages. If a song you want runs over, crop harder rather than letting the firmware truncate mid-phrase — the advice in the fit-a-song guide applies doubly at half the budget.