Blackbox

The Blackbox records flight data many times a second: stick inputs, setpoints, gyro, PID terms, mixer and servo outputs, motors, RPM, battery, governor and more. Logs are the most useful tool there is for tuning and for finding out what went wrong.

The Blackbox tab page covers the settings in the Configurator. This page is the background.

Where logs go

blackbox_device
SPIFLASH	The flight controller's flash chip -- 16 MB to 256 MB on Rotorflight boards.
SDCARD	An SD card on the flight controller.
SERIAL	An external logger on a UART -- see OpenLager.
NONE	No logging.

Getting logs off

• Mass storage mode (the Blackbox or Setup tab, or msc in the CLI) makes the flight controller a USB drive; copy the logs off as files. The fastest and most reliable way.
• Save to file in the Configurator downloads over MSP -- slow, and can corrupt large logs.
• With an external logger, take out its SD card.

Open the logs in the Blackbox Explorer (or the desktop version).

Logging rate and space

blackbox_rate_denom divides the PID loop rate: at a 2 kHz PID loop, 1 logs at 2 kHz, 2 at 1 kHz, 4 at 500 Hz.

For	Use
Filter tuning, vibration	The highest rate the device can manage -- 1-2 kHz.
PID and governor tuning	500 Hz - 1 kHz.
General flying, long logs	250 Hz or less.

Higher rates and more fields fill the flash faster. Every field you don't need (blackbox_log_* = OFF) leaves room for more flights.

Logged data

Setting	Logs
blackbox_log_command	Stick commands
blackbox_log_setpoint	Rate setpoints
blackbox_log_mixer	Mixer inputs
blackbox_log_pid	P, I, D, F, B and O terms
blackbox_log_attitude	Attitude estimate
blackbox_log_gyro_raw	Unfiltered gyro (for filter tuning)
blackbox_log_gyro	Filtered gyro
blackbox_log_acc	Accelerometer
blackbox_log_mag	Compass
blackbox_log_alt	Altitude
blackbox_log_gps	GPS
blackbox_log_battery	Battery voltage and current
blackbox_log_rssi	RSSI
blackbox_log_motors	Motor outputs
blackbox_log_servos	Servo outputs
blackbox_log_rpm	Motor and rotor RPM
blackbox_log_vbec / blackbox_log_vbus	BEC and bus voltages
blackbox_log_temp	Temperatures
blackbox_log_esc	ESC telemetry
blackbox_log_bec	BEC telemetry
blackbox_log_governor	Governor state, target and throttle

When it logs

blackbox_mode
ARMED	Whenever armed (default since 2.3).
SWITCH	While the BLACKBOX mode switch is on.
NORMAL	While armed and the switch is on.
OFF	Never.

blackbox_grace_period keeps logging for a few seconds after disarming. blackbox_rolling_erase (default on) overwrites the oldest logs when the flash is full; blackbox_initial_erase_kb erases enough space before a log starts.

Debug data

debug_mode adds eight extra values to the log for investigating one subsystem -- for example GOVERNOR, RPM_FILTER, RPM_SOURCE, TTA, AIRBORNE, DYN_NOTCH, ESC_SENSOR, CRSF_LINK_STATISTICS_UPLINK. debug_axis picks the axis for modes that work per axis. The full list is under debug_mode in CLI Settings.

The log format is described in the Technical Reference.