I live in Poland and I might do not do the best job describing my problem I also don’t have a lot of knowledge so It makes it even harder for me, so please be forgiving. What is going to be more painful is schematic that I’ll attach please note its my first project. Obviously I’m open for any criticism.
I’m 17 and studying /learning computer science so I decided to designed flight controller for drone (operating on open software Betaflight) without any electronic background what so ever. It wasn’t easy (switching miso with mosi or d+ with d-, or just soldering mcu rotated by 180 degrees

) but I got drone to fly. Now I have problem with power supply to my electronics i know for the fact that my input voltage is pretty noisy, because after connecting directly analog camera to it, I saw those typical artifacts/lines. Whole control setup is rather OK but biggest noise creator are brushless motors (5k-21k rpm with 12 magnets I have know idea what frequencies are generated by those) which are powered by the same li-po. which is problematic by it self because in Blackbox is saw on heavy load it can drop from 12,2V to 9V in 1ms(during two cycles at 2kHz). The TPS62133RGTR 5V regulator cant handle it alone and my RCreceiver which is connected to it is shutting down during that dropout.
After flying for longer (and some crashes) my gyroscope and accelerometer started to freak out, output of those even during small movement was increased( was showing much to big values) in addition it seemed really noisy/not stable. Reason why I think its caused by the 5V rail is that at the same time I noticed significant decreased in RClink strength. Those are things I need to know:
1.do I need oscilloscope to get to the source of those problems(It might be to weak battery, defective motor driver, or most likely my bad design because I didn’t add any additional filtering like “capacitance multiplayer”, lc filter, inductor between bat+ and regulator input. Just some decoupling capacitors and components needed from datasheet of regulator)
2. are there any specific methods with such a noise input voltage( I think its pointing out that I’m using max 2A on that 5V rail)
3. I noticed that by stopping brushless motor physically while it’s driven by ESC it courses huge power waste/consumption for short amount of time => short voltage sag. i guess that voltage regulator reacts to lover voltage but it doesn’t react fast enough while voltage of battery go backs to normal and kills electronics that was able to destroy my previous flight controller which I bought online I’m assuming that was similar problem occurred that I have now. How can I protect mcu, and other sensitive electronics from such a short voltage drop on battery rail.