Your BLHeli_S ESC Is Missing RPM Filtering. Bluejay Fixes It
Quick Answer
Bluejay is the firmware we would choose for a compatible 8-bit BLHeli_S ESC when you want bidirectional DShot, RPM filtering and Extended DShot Telemetry without replacing the hardware. It is not a BLHeli_32 or AM32 replacement for 32-bit ESCs: first identify the ESC processor and layout in ESC Configurator.
Bluejay vs BLHeli_S vs 32-bit firmware
The original BLHeli_S firmware can run DShot, but it does not return the fast eRPM data Betaflight needs for RPM filtering. Bluejay adds that return channel on supported EFM8-based BLHeli_S hardware. Betaflight now recommends Bluejay for 8-bit ESCs, while AM32 and existing BLHeli_32 installations belong to a different 32-bit hardware family.
| Firmware | Typical hardware | RPM filtering | Our recommendation |
|---|---|---|---|
| BLHeli_S 16.7 | 8-bit EFM8 ESC | No native bidirectional DShot | Keep only when Bluejay compatibility is uncertain |
| Bluejay | Compatible 8-bit BLHeli_S ESC | Yes, with bidirectional DShot | Our default upgrade for supported 8-bit hardware |
| BLHeli_32 | 32-bit ARM ESC | Yes on suitable versions | Do not flash Bluejay; BLHeli_32 licensing ended in 2024 |
| AM32 | Supported 32-bit ARM ESC | Yes | Buy it as AM32 hardware or follow a board-specific migration procedure |
This distinction matters in our catalogue. The SpeedyBee F405 AIO 40A is listed with an integrated 40A Bluejay ESC, while the T-Motor Velox V45A Lite V2 is listed as BLHeli_S hardware that can be upgraded. Do not choose firmware from the current rating or the flight controller name; read the detected ESC target.
What RPM filtering actually changes
With bidirectional DShot enabled, each ESC returns eRPM over its motor signal wire. Betaflight places narrow notch filters at the motor’s fundamental frequency and harmonics instead of asking broader filters to cover the same motor noise. This can reduce filter delay and improve motor-noise control, but it does not repair bad bearings, damaged props or a flexible frame.
Set the motor pole count correctly: Betaflight means magnets on the motor bell, not stator arms. Fourteen is common on 5-inch motors, but smaller motors may use twelve. A wrong value makes the filter follow the wrong frequency even when telemetry appears healthy.
How to flash Bluejay without guessing
- Remove the propellers, connect the flight controller by USB, then apply battery power so the ESCs are awake.
- Open ESC Configurator in a supported Chromium-based browser and read all ESCs before changing anything.
- Save or photograph the detected targets, motor directions and current settings. Flash the stable release offered for that exact layout; never substitute a similar-looking target.
- Avoid Bluejay 0.20.0. ESC Configurator warns that its stall detection and motor protection can damage ESCs or motors; the current stable GitHub release is 0.21.0.
- Copy the previous motor directions, then check each motor individually with propellers still removed.
- Enable bidirectional DShot in Betaflight, set the correct motor poles and inspect DShot telemetry errors before the first hover.
For 4k or 3.2k PID loops, Betaflight recommends DShot300 for reliability; DShot600 is needed for 8k8k. Older BB1 “L” ESCs are the exception: Betaflight recommends DShot150 with a 2k PID loop because their MCU is slower. Our fuller ESC firmware flashing guide covers the recovery and configuration sequence.
Choosing 24, 48 or 96kHz PWM
Do not treat a higher PWM number as a universal upgrade. Bluejay offers 24, 48 and 96kHz builds, but increasing frequency reduces undithered PWM resolution and changes motor behaviour. We would start with the hardware maker’s setting, use 48kHz as a measured middle option where appropriate, and change it only after checking motor temperature, startup reliability and flight logs.
If you are replacing hardware rather than reflashing it, browse our flight controllers and electronics by firmware and processor family, not merely by amp rating.
FAQ
Does Bluejay Configurator still exist?
Use ESC Configurator at esc-configurator.com. The old standalone Bluejay Configurator is not the recommended route for current releases.
Can Bluejay be flashed to a BLHeli_32 ESC?
No. Bluejay targets compatible 8-bit BLHeli_S hardware. A 32-bit ESC needs its existing BLHeli_32 firmware or a board-supported AM32 path.
Does flashing Bluejay enable RPM filtering automatically?
No. You must also enable bidirectional DShot in Betaflight, enter the correct motor pole count and confirm low telemetry errors. Keep the propellers off until motor order and direction pass.