I started down a similar path with my
V-22 Project and found that none of the off-the-shelf drone controllers would do VTOL or helicopter modes. I don't know the first thing about programming for F3/F4 flight controllers, but I'm pretty adept at Arduino, so I took
Tom Stanton's idea and used an Arduino to provide servo mixing based upon the stabilized output from my Frsky S8R receiver.
There are several methods to use an Arduino to read RC PWM servo signals, but most are limited to a few inputs and they are quite slow. The best one I found is based on
pin-change interrupts that can handle many channels at once and is very responsive.
