First of all: Arducopter is a really great an sophisticated project.
This is my fourth multirotor and my first Quad with APM 2.0 (others: Quad multiwii, Tri multiwii, Quad Naza, Blade mqx :) ) and the apm2 flies really well in stab mode - though acro seems to me is still the domain of multiwii, even compared to the - in my opinion - highly overrated naza (btw i will def. not buy another naza unit for several good reasons, but thats only me). I will dig in tuning the GPS-thing after the next FW release because i only use RTH as failsave and that works quiet well for me on stock settings.
After googling and reading the wiki i still have some points:
1. I use the FrSky D4FR in ppm mode (jumper) on my apm2 (jumper). It also puts out the rssi signal as pwm. From my understanding the apm needs an analog voltage as rssi input. Is there a software way without extra components to put the pwm rssi directly into the apm? It would be nice for the OSD.
2. I have the FrSky Ampere Sensor (FAS-100) sometimes connected to my other setup with FrSky D8R-II receiver. This ampere sensor puts out a serial data stream. Is there a way to connect it to some serial port on the apm and get it read out by the software? It also would be nice for the OSD.
For the first time i use the very cheap Hobbywing SkyWalker 20A ESC in my quadsetups (9,50€). They use the SIL chip - so no flashing at the moment. Sometimes not all of them will arm at 490Hz PWM frequency so i lowered it in the missionplanner to 400 Hz and the issue is resolved. Besides this they fly very well don't heat up (with 12A rated motor) and i didn't notice a different flightbehaviour from the lowered pwm freq. What are your experiences with these ESC at 490Hz?
4. For voltage monitoring of my 3S (max 12,6V) setup i use the diy voltage devider in the picture below. I calibrated it in the missionplanner with a multimeter and it seems to work. Is it ok like this or is it dangerous that way?
Thanks for your patience reading this stuff!