38 lines
2.2 KiB
Markdown
38 lines
2.2 KiB
Markdown
# Miscellaneous notes
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These are random AP-related notes that wouldn't fit anywhere else:
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## Performing an autotune
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The [ArduPilot Autotune documentation](https://ardupilot.org/plane/docs/automatic-tuning-with-autotune.html) and the [demo video](https://www.youtube.com/watch?v=Ud_YPu7fgXE) are very detailed on this, but here's the gist on how to run an autotune.
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Some things to know are:
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- Autotune does not tune the rotation rates, but does not really depend on them either.
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- You should set `AUTOTUNE_LEVEL` depending on the size of your aircraft. For small/agile craft, you can set `AUTOTUNE_LEVEL` to 7 or more. For larger, more sluggish craft, 6 (or less) is a good level. Under the hood, a higher `AUTOTUNE_LEVEL` decreases `*2SRV_TCONST` and increases `*2SRV_RMAX`).
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Before you switch into `AUTOTUNE` mode, complete a circle or fly in different directions to allow the airspeed estimator to get an accurate value before running the autotune (or tuning the TECS). After you switch into `AUTOTUNE`, start with left and right roll inputs at maximum stick deflection. You don't need to wait until you hit the max roll angle, what I tend to do is roll max right, leave it for half a second, then roll max left, repeat.
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The OSD will start showing you PID numbers, continue until a message saying `ROLL FINISHED` appears. Afterwards, do the same with pitch. Hit full stick deflection up and down, without reaching max pitch limits.
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After the `PITCH FINISHED` message appears, continue flying in `AUTOTUNE` for more than ten seconds, to make sure the tune values are saved.
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You're done, you can switch to any other mode and continue flying.
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_(Thanks to Mike for the above info.)_
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## DMA on the Matek F405-Wing
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If you want to get DMA on UART3 of the Matek F405-Wing FC (or, more relatedly, the Racerstar F405, because UART1 is Bluetooth there), you can open `libraries/AP_HAL_ChibiOS/hwdef/MatekF405-Wing/hwdef.dat` and comment out line 92ish, where PA15 is defined.
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That will enable DMA on UART3, at the expense of disabling the LED pad.
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* * *
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<p style="font-size:80%; font-style: italic">
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Last updated on January 22, 2022. For any questions/feedback,
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email me at <a href="mailto:hi@stavros.io">hi@stavros.io</a>.
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</p>
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