Betaflight

Betaflight is the open-source firmware that runs FPV flight controllers. It turns gyro data, your rates, and a PID loop into the motor commands that keep you in the air.

Quick reference

The essentials you reach for on every build and tune — each section below expands on one of them.

• Flash + Configurator — Firmware Flasher → pick target + latest stable (4.6), Load Online. Configurator is date-versioned (2025.12+).
• PID profiles — Up to 6 profiles; switch with profile N. Tune P → D → I → F per quad.
• Rates — rates_type = ACTUAL sets center + max deg/s directly; switch with rateprofile N.
• Filters & dynamic notch — RPM filter first (dshot_bidir = ON), then dynamic notch, then raise lowpass cutoffs.
• Modes — ARM on a dedicated switch; ANGLE self-levels, ACRO is default, AIRMODE on for freestyle.
• DShot — DShot300/DShot600 on the Motors tab; dshot_bidir adds RPM telemetry.
• CLI diff / dump — diff all is your whole tune; dump all is the full config. Back up before changes.
• Arming flags — status prints why it won’t arm — RX_FAILSAFE, THROTTLE, CALIBRATING…

⚡: Props off for every bench step. Flash, motor test, and first arm are the dangerous moments — no props, and no battery when USB is enough.

What Betaflight is

Betaflight is open-source firmware for flight controllers (FCs). It reads the gyro, runs the PID loop, and drives the ESCs — the brain between your radio and the motors.

1. Flight controller firmware

Runs the gyro → PID → motor loop at 4–8 kHz to control roll, pitch, and yaw.

2. Targets

Firmware is built per board target, e.g. STM32F405 (S4FO). The Configurator auto-selects it when you flash.

3. Configurator

The GUI (Betaflight Configurator 2025.12+ (date-versioned)) edits every setting; the CLI exposes the same values as text.

4. Board orientation

The FC’s arrow must face forward. If it’s mounted rotated, set Board & Sensor Alignment so up and forward match the quad.

Sticks (RC input) → Receiver (SBUS / CRSF) → FC · PID (gyro + loop) → ESC (DShot) → Motors (thrust)

KEY: Read the loop left to right. Your sticks become a requested rotation rate, the gyro measures what actually happens, and the PID loop corrects the difference up to 8,000 times a second. Rates set the target, PIDs chase it, filters clean the signal.

Setup & firmware

Flash the right target, set your ports and protocols, then confirm the gyro sees the correct axes before you ever arm.

1. Enter DFU mode — Hold the boot button while plugging USB, or type bl in the CLI.
2. Flash firmware — Configurator → Firmware Flasher: pick target + version, then Load Online (or a local hex).
3. Apply defaults — Press Apply Custom Defaults or restore the board’s factory configuration.
4. Configure — Calibrate the accelerometer, set board/sensor alignment, then ports and protocols.

SBUS CRSF ELRS IBUS F.Port DShot300 DShot600 Bluejay

!: Props off for the whole setup. A stray arm during flashing or motor testing spins all four motors at once. Remove props, and leave the LiPo unplugged when only USB power is needed.

PIDs

P chases the error, I holds attitude, D damps the response, and feedforward adds stick input straight to the motors.

Sample 5-inch PIDs

Betaflight 4.x defaults — a sane starting point for a 5-inch freestyle build.

# PID profile 1
set p_roll = 45
set i_roll = 90
set d_roll = 40
set f_roll = 100
set p_pitch = 50
set i_pitch = 90
set d_pitch = 40
set f_pitch = 100
set p_yaw = 45
set i_yaw = 90
set d_yaw = 0
set f_yaw = 100

PID profiles

Up to 6 profiles, switched with profile N or the Adjustments tab. Keep one per build — tune per quad, not per pack.

profile 1   # switch profile
set p_roll = 42
save        # persist to flash

1. Raise P — Increase until it feels crisp and just starts to oscillate, then back off a few points.
2. Raise D — Add D to kill bounce and propwash; stop when motors run hot or D sounds rough.
3. Set I — Raise I until it holds attitude against wind without slow wobble.
4. Add feedforward — Increase F for snappier stick response; reduce it on overshoot.

⌁: D amplifies noise. Raise D only after the filters are clean (see Filters); otherwise you trade propwash for hot, noisy motors.

Rates

Rates convert stick position into a requested rotation speed in degrees per second. They define how the quad feels, not how stable it is.

ACTUAL vs BETAFLIGHT

rates_type = ACTUAL sets the center deg/s and the max deg/s directly (recommended). BETAFLIGHT is the legacy RC rate + super rate + expo formula.

set rates_type = ACTUAL
set roll_rc_rate = 100   # deg/s at center
set roll_srate = 70      # super rate 0–100
set roll_expo = 0        # center softening

Rate profiles

Up to 6 profiles, switched with rateprofile N. Keep a race profile and a freestyle profile, or assign them per flight mode.

rateprofile 1
set pitch_rc_rate = 100
set yaw_rc_rate = 100
save

set rates_type = ACTUAL
set roll_rc_rate = 100
set roll_srate = 70
set roll_expo = 0
set pitch_rc_rate = 100
set pitch_srate = 70
set pitch_expo = 0
set yaw_rc_rate = 100
set yaw_srate = 70
set yaw_expo = 0

→: Start at defaults and change one axis at a time. A few points of super rate is a large change in feel; max rate is where most people feel the difference first.

Filters

Filters strip gyro and motor noise so the PID loop sees only real movement. Too much filtering adds latency; too little cooks motors.

Gyro (raw samples) → Lowpass (gyro_lpf) → Notch (dyn + RPM) → PID (P · I · D · F) → Motors (DShot)

Bidirectional DShot + RPM

Enables ESC → FC RPM telemetry, which the RPM filter locks onto. Needs BLHeli_S/32 (or Bluejay) ESCs.

set dshot_bidir = ON
set motor_poles = 14   # match your motor
# verify per-motor RPM:
dshot_telemetry_info

Clean baseline (5-inch)

A quiet starting point; raise cutoffs until it’s clean but not mushy.

set gyro_lpf1_static_hz = 250
set gyro_lpf1_dyn_min_hz = 250
set gyro_lpf1_dyn_max_hz = 500
set dterm_lpf1_static_hz = 75
set dterm_lpf1_dyn_min_hz = 75
set dterm_lpf1_dyn_max_hz = 150
set dyn_notch_count = 3

lowpass notch dynamic static RPM filter bidi-DShot

⚠: Under-filtering = hot motors and mid-throttle oscillations; over-filtering = a mushy, delayed quad. Set up RPM filtering first, then raise the lowpass cutoffs until it flies clean.

Modes & features

Modes are armed by AUX switch ranges on the Modes tab. Assign each to a switch position; only one flight mode (angle / horizon / acro) is active at a time.

Arm switch then Throttle lift off Disarm touchdown

• Disarmed — Motors off; arming checks pass before the switch arms.
• Armed — PID loop live; throttle controls thrust. AIRMODE keeps authority.
• Failsafe stage 1 — Link lost — wait failsafe_delay before acting.
• Failsafe stage 2 — Drop, land, or GPS rescue, depending on config.

✓: AIRMODE keeps fighting when the ground touches it. Land by disarming just before touchdown — otherwise the quad bounces and skitters. Assign arm to a dedicated switch, not the throttle.

CLI

Every GUI setting is a CLI variable. diff all is your whole tune in one paste; set changes a value; save writes it to flash.

• diff all — Only settings that differ from defaults — your saved config.
• dump all — The full config: settings, resources, aux, vtxtable.
• get rates_type — Read a setting, its current value, and valid range.
• set rates_type = ACTUAL — Change a setting (persist with save).
• save — Write current settings to flash.
• defaults — Reset everything to firmware defaults.
• bl — Reboot into DFU/bootloader for flashing.
• status — Arming flags, voltage, gyro, version — read first when it won’t arm.
• tasks — CPU load per loop/task (keep the busiest below ~60%).
• resource — List the pin → function map.
• resource MOTOR 1 B00 — Remap motor 1 to pin B00, then save.
• resource show all — Print the full resource map.
• vtx — Current VTX table, band, channel, and power.
• beeper — Trigger the beeper; beeper -GYRO_CALIBRATED lists flags.
• dshot_telemetry_info — Per-motor RPM telemetry (verify RPM filter).
• motor — Spin each motor in sequence — props off!
• version — Firmware, target, and configurator versions.

vtxtable bands 5
vtxtable channels 8
vtxtable band 1 BOSCAM_A A FACTORY 5865 5845 ...
vtxtable powerlevels 4
vtxtable powervalues 14 20 26 30
vtxtable powerlabels 25 100 400 800

resource
resource MOTOR 1 B00
resource MOTOR 2 B01
resource MOTOR 3 A03
resource MOTOR 4 A02
save

⌘: Paste your diff all into a text file before every major change — it’s a one-command backup of the entire tune.

Pitfalls

The five mistakes that turn a fresh build into a flipped quad — or a hospital trip.

Props off when testing

Arming spins all four motors instantly. Remove props before the motor tab, motor, or any bench tuning — and never arm a quad you’re holding.

motor   # motor test — PROPS OFF

Motor order & direction

Motors must match the wiring diagram and spin the right way, or the quad flips on arming. Reverse rotation in the BLHeli/Bluejay configurator — not in Betaflight.

dshot_telemetry_info   # verify RPM per motor

Board orientation

If the FC arrow isn’t forward, the gyro corrects the wrong axis and it flips. Set Board & Sensor Alignment, then watch the 3D model in Setup follow the real quad.

set align_board_yaw = 90   # if arrow is rotated

Failsafe not configured

Defaults may keep the motors running or drop without warning. Set Drop (or GPS rescue), and verify by switching the radio off while armed on the bench.

set failsafe_switch_mode = STAGE1
status   # check the arming flags

Filter over-tuning

Too-low cutoffs feel mushy and can still overheat; too-high amplifies noise into hot motors. Change one filter at a time and test in the air.

get gyro_lpf1_dyn_min_hz   # before you touch it

Arming disabled flags

“Why won’t it arm?” — status prints the exact reason as flags: RX_FAILSAFE (no link), THROTTLE (stick not down), ARM_SWITCH, CALIBRATING, MSP, CLI. Fix the flag, not the switch.

status   # list arming disable flags

ESC protocol mismatch

If the FC outputs DShot but the ESC is configured for Oneshot/PWM (or vice versa), motors can runaway or the quad flips on arm. Match the protocol in the Motors tab and the ESC configurator.

set motor_pwm_protocol = DSHOT600
save

RX_FAILSAFE THROTTLE ANGLE ARM_SWITCH CLI CALIBRATING

⚠: The rule again: props off. Nearly every Betaflight injury is a quad that armed with props on during setup. Remove them, and only arm with the quad secured.