This code cuts D by a specified percentage durning normal flight.
It lets D smoothly rise up to normal during rapid gyro moves like flips and rolls, and increase during prop wash events.
D should now be tuned to values the 'normal' 30-45 range.
If D is 40, a dterm_cut_percentage of 65 will cut D to 14 in normal flight, but the quad will still get full 40 of D to control bounce-back after flips and about 25 of D during strong prop wash.
The dterm_cut_percentage can be adjusted via the OSD, from the D filtering page.
Adding d_cut results in cooler motors, lower amounts of noise in motor traces and faster reactions to quick stick inputs.
Too high a dterm_cut_percentage may bring out P oscillation from lack of D. Values of 70% are generally OK.
Input is gyro differential (delta). Frequencies above 40hz (above propwash) are attenuated with a configurable (dterm_cut_range_hz) biquad filter. Lower values for range can be used if the quad is very noisy or gets low frequency D resonant oscillation. Up to 50 or 60hz may suit clean quads where prop wash control is the main priority. Too high a range value results in D being boosted from noise in normal flight.
The boost signal is 'integrated, smoothed and delayed' with a 7hz PT1 'dterm_cut_lowpass_hz' filter. The default of 7Hz gives about the right amount of smoothing and delay. Higher numbers cause the boost to come on faster, with less delay. Lower values delay the boost effect and cause it to last longer.
The dterm_cut_gain amount controls the strength of the boost effect by amplifying the input to the boosting effect. If the quad is flow gently, a higher gain value may be needed to gain full boost.
Logging with set debug_mode = D_CUT allows recording of realtime D values on roll and pitch into debug 2 and 3. The reatime D value should reach its set maximum during rapid turns, ideally at about the time D itself peaks. If it fails to reach the maximum, gain should be increased.
The D_Cut feature is not enabled on LUXV2RACE, OMNIBUS, SPRACINGF3NEO because there isn't enough flash space.
When using external XJT it annoyingly beeps when A1 drops below 3.7v (72 out of 255). I removed frsky_spi_use_external_adc and added frsky_spi_a1_source = VBAT, EXTADC, CONST. To prevent XJT from beeping ever set CONST and XJT will assume that the "reciever" is powered with 5v. I messed up previous PR #7305 branch so I decided that it's easier to open a new one.
Closes#7297
Adds support to persist the RTC (if set) across the reboot if entering mass storage mode for on-board flash. The value is then used as the timestamp for the files exposed in the virtual FAT32 filesystem. The files will then have reasonable creation dates when copied to the host computer.
If the RTC is not set (or supported), then the default timestamp of 2018-01-01 will be used (unchanged from previous).
Included some improvements to the RTC functions and exposed the `tz_offsetMinutes` in the `timeConfig` PG. Support already existed for timezone offsets but the parameter wasn't exposed to the user and couldn't be set.
Move timezone offset up a layer as a parameter to systemResetToMsc()
Adds support for specifying a custom timezone offset from both the CLI and MSP calls to enter mass storage mode.
Added an option timezone offset minutes to the CLI `msc` command. If no parameter is specified then the default as specified by `timezone_offset_minutes` will be used. So to reboot into mass storage mode and force the file timestamps to be in UTC, use `msc 0`.
Added reboot message `MSP_REBOOT_MSC_UTC` to support rebooting into mass storage mode and forcing the timestamps to use UTC time (0 offset). The Configurator will need to be modified to use this message for operating systems that expect UTC times for FAT file systems (like Linux).
