I have an octo and am installing a gimbal using the wiki. I've done this before on quads but not with an octo.
Since I'm using digital servos, I wanted to set to another channel since A10 and A11 are 50hz. In the MP it doesn't allow choosing A9 but does allow A5-8. So I moved my pitch and roll to A7 and A8 and chose RC8 and RC9 in the MP. First it didn't work so I decided to change it back to A10 and A11. I'm just using the servo's signal wire and powering the servos via 6v BEC. I first changed the signal wires to A10 and A11 and then booted up the APM2.5 so I could change it to RC10 and RC11 in the MP. After about a minute or less, some of the motors spun up. Not so much to lift off but if someone was near one, they would have had some problem. Note that the Tx was on, MP was auto reconnecting and copter was of course disarmed. I had just plugged it in. So I pulled the battery and tried again. It happens every time. The only solution was to have someone hold down the octo while I changed the MP to use A10 and A11, then the motors stopped.
Is it possible the octo code is occupying these channels for some of it's motors? I noticed it was the same few motors each time.
What should I use for digital servos? A5 and A6?