Butterflight is a new flight firmware that was forked from the widespread Betaflight firmware. A few enthusiasts decided to fork and make their own version of flight firmware with a focus on flight characteristics and ease of configuration. Its OpenSource repository can be found here.
What is Butterflight?
Butterflight is a fork of Betaflight that aims to bring a renewed focus on Mini Quad Flight Performance. Developers want to push the envelope of what is possible in terms of raw flight characteristics keeping freestyle and racing pilots desires on the forefront. Clean flight performance and ease of use and that is what they plan to deliver.
Betaflight is currently on a feature freeze and many people have been left without access to the fast kalman filters they were once testing before. Butterflight repository will be a stop-gap until this all gets sorted so folks can continue to test and fly what they like.
Support for incorrect Smart Audio protocol
Butterflight has a compatibility mode for AKK VTX’es with incorrectly implemented Smart Audio protocol that was removed in the previous Betaflight updates (Betaflight 3.3). You can now select this mode via CLI and make your old AKK VTX’s compatible and fully operational via OSD.
set vtx_akk_hack = on | off
Enabling FAST KALMAN filter
If you want to test the Fast Kalman Filters you will have to change a couple of settings via CLI. Process is quite simple, open Butterflight Configurator (10.2.0) and enter these commands:
Make sure to set Dterm Lowpass filter to PT1
Enable Dynamic Filters | Airmode | Anti-Gravity (8k8k on a non 32k board)
Disable all Notch filters
set gyro_use_32khz = ON (32Khz IMU Only)
set cpu_overclock = 192MHZ (F4 Only | 32 Khz IMU)
set gyro_stage2_filter_type = FAST_KALMAN
set gyro_filter_q = 400
set gyro_filter_r = 88
And you should be good to go. First a quick hover test for hot motors then it’s too the sky!
Main website: http://butterflight.co/
You can get Butterflight firmware from here: https://github.com/ButterFlight/butterflight/releases Or you can upload the firmware straight from the Configurator.
You can get Butterflight Configurator from here: https://github.com/ButterFlight/butterflight-configurator/releases
EDIT 2018-03-01: If your quad refuses to arm, try this command:
also wait a little with the quad still before arming, the filter needs a little time to get it’s head in order.
Edit 2019-01-21: This graph shows the number of commits of Butterflight vs Betaflight. Not much movement seen lately on Butterflight.