How to set up blackbox logging for tuning
A tune is only as good as the flight log behind it. Before any tool, or any person, can tell what your quad needs, the log has to record the right data at the right rate.
What a tuning log needs
- Somewhere to record. Onboard flash or an SD card. Boards without either can’t log a flight.
- About 2 kHz logging. That shows noise up to about 1 kHz, which filter tuning needs. On boards with a BMI270 gyro, 1.6 kHz is the practical rate. PID tuning alone works from 1 kHz.
- Unfiltered gyro. It shows the noise before the filters, so you can see what the filters are doing. Betaflight 4.5 and newer log it as standard. On 4.3 and 4.4, set the debug mode to
GYRO_SCALED. - Room for a whole pack. Turn off the log fields tuning doesn’t use (accelerometer, attitude, GPS, magnetometer, altitude and RSSI) so the memory lasts longer.
- Empty memory. Save any old logs you want to keep, then erase the flash before the test flight. FPV PID Tune does both for you at Connect, and clears the memory again after each flight it has read.
Settings by firmware
| Firmware | debug_mode |
Logging rate |
|---|---|---|
| 4.3, 4.4 | GYRO_SCALED |
About 2 kHz; 1.6 kHz on BMI270 gyros |
| 4.5 | NONE |
About 2 kHz; 1.6 kHz on BMI270 gyros |
| 2025.12, 2026.6 | NONE |
About 2 kHz; 1.6 kHz on BMI270 gyros |
GYRO_SCALED no longer exists in 2025.12, so don’t carry it over from an old diff. After a settings reset on 4.5 and newer, the blackbox device is set to none, so check it’s pointing at your flash or SD card.
Fly the test pack
Fly these in any order, with a short hover between each set. Fly in Acro mode: Angle mode limits the tilt, so the snaps don’t give a usable step response.
- A slow throttle sweep, about 10 seconds from low to full, then back down.
- About 10 snap rolls: full stick, held until the quad has rolled all the way round.
- About 10 snap flips: same on pitch, backwards is fine.
- About 10 yaw spins at full stick. A longer spin is fine.
- A few split-S and two punch-outs (full throttle for about a second, then chop). They show propwash and how the quad holds up at full throttle.
Pick a calm day. Wind shows up in the log as noise you can’t tune away.
Or let FPV PID Tune do it
When you plug in, FPV PID Tune backs up your settings and sets up logging for your firmware and gyro, without touching your tune. When you’re done tuning, it offers to put your original logging settings back, since tuning-grade logging uses extra processing.