How to setup the mode switch for APM/AC2

This tutorial was created using the Futaba 12fg, but keep reading and it may give you some ideas on your radio. If you already have your particular radio figured out, write a tute like this and maybe we can get a collection of them added to the APM/AC2 wiki's.

You will need two spare switches, a 2 position and a 3 position to be able to get all six flight modes for the APM/AC2. We are aiming to get pulse widths of 1165, 1295, 1425, 1555, 1685, and 1815.

If you have a device which can measure pulse width, it is much more convenient than watching numbers scroll on the cli. The pulse-width readout is now conveniently located on the Radio Calibration page of the Planner. Some servo testers can measure what is coming out of the receiver.


1. Start with end points at 100 and subtrim 0 on the gear ch.


2. Go to the AFR screen #2 and set the function to Gear.


3. Put Gear switch in middle the position. Now backup to AFR screen #1 and set the offset to get a pulse of 1490. This is not the normal centre pulse width but is right in the middle of the range we are trying to setup. This could be done with subtrim on other radios.


4. Go to the Prog Mixes screen, pick a mix and set it to Offset, then activate it to get to the next step.


5. You should now be in the setting screens for your chosen mix. Go to screen #5 to assign a switch to use as your secondary mode switch and remember to activate it. I chose SF as it was a 2 position switch.


6. Go to Mix screen #1 and set the function to Gear.


7. Set the secondary mode switch to the rear and Gear switch to centre and adjust Offset Off for a 1425 pulse.


8. Set the secondary mode switch forward and adjust Offset On for a 1555 pulse.


9. Go back to AFR screen #1 and make sure you are still in the Gear function. Put both switches to the rear and adjust Rate B for an 1165 pulse. This can be done with gear endpoints on other radios.


10. Flick both switches all the way forward and adjust Rate A for an 1815 pulse.


11. That’s it. If you flick through all 6 combinations, it should be pretty close to what the APM/AC2 expects to see. I ended up with 1165, 1296, 1426, 1555, 1684 and 1814.


Here is the file for my complete model. I would suggest using it as a guide only because my switch assignments may not suit you.



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Comment by DaveyWaveyBunsenBurner on May 13, 2011 at 5:04am

Awesome post Gordon!


I keep trying to get my head around Futaba mixes but fail!

Comment by Tom on May 13, 2011 at 5:37am
Wow you lost me on this why are they making it so hard to set your modes i have a Aurora-9 and im having a very hard time with setting modes but thank you for putting this up im sure it will help a lot of guys with a futaba radio but im still lost  Tom
Comment by Gordon on May 13, 2011 at 6:16am

I switched over from a DSX-9 about 6 months ago and am only just now starting to get my head around Futaba programming as well. Futaba's best point is that it is so flexible and customizable, its worst point is that it is so flexible and customizable


I really hope other people will post something similar for the other brands. I have a Turnigy 9X with ER9X firmware that I would like to know how to setup so it can become my LRS system when I eventually get a second APM to do a long range plane.

Comment by Olivier on May 13, 2011 at 6:22am

Here is same for Turnigy 9x (ER9X firmware) with "F. mode (AUX3)" 3 positions switch mixed with "AIL. D/R" 2 positions switch.


pos 1 : Aux3 up, Ail up

pos 2 : Aux3 middle, Ail up

pos 3 : Aux3 down, Ail up

pos 4 : Aux3 down, ail down

pos 5 : Aux 3 middle, Ail down

pos 6 : Aux 3 up, Ail down


Here is a snapshot from eepe software.

Comment by Darren on May 13, 2011 at 6:25am

I did a similar write up (sans pictures) for the Turnigy with ER9x firmware. I also saw recently a Turnigy 9x with stock firmware  writeup. (although you lose a dial with stock firmware)

But the biggest advice I can give when setting up modeswitch mixing is; that it is way easier to setup your switch mixes while watching the "cli mode, test, pwm" text output. Try to get your modeswitch(s) tweeked to ouput pwm as close to published as possible.


Always remember that the MUX (APM Control) is only engaged (Amber LED on mainboard Lit)  when pwm is below 1750, else its in Hardware Manual.

Comment by Ritchie on May 13, 2011 at 6:34am
Dave use the CLI to read your radio output. Once you know the PWM for your switches you can tell which of the reading you can select. As I have a 6EX I have two switches spare so one is for hardware failsafe and the other switches between two modes grouped as 123 and 456. Ive also change the sides of the switches to make it easier to switch.
Comment by Gordon on May 13, 2011 at 5:21pm

Great stuff, that has the Turnigy with ER9x covered. I so wish there was an eePe for every brand. Now how about the vanilla Turnigy, Hitec and JR/Spectrum. Lets get this all in one place to make it easier for the DIY community.



I wrote this mainly with AC2 in mind which uses ch5 for mode selection. Could you confirm that 1815 will not put AC2 into hardware manual because it doesn't use ch8. You are spot on about using the cli, I first started by guessing at mixing numbers. Once I started using real pwm values it was easy. The hard part for most people is understanding the radio, which is why I would love to see this stuff end up in the wiki. More info = more users = more money for DIYDrones to use on R&D for even more cool toys.

Comment by Luke on May 14, 2011 at 10:08am

There's a JR9303 tutorial here, though I agree, it doesn't cover all JR. This here is a great addition since many people are using Futaba, though most use the 7C/9C. In the comments over on the other thread there still seemed to be some confusion for the 7C.

I agree this should be added to the wiki - hopefully Chris will see it. I think it would be better too if the links in the wiki could indicate which tutorial to use for which radio, instead of having the link buried in the text as it is now.


Comment by Gordon on May 14, 2011 at 5:16pm

@Luke excellent writeup for the 9303. Just shows how fast good info gets buried in blog/forum systems, your post was only a month before mine and I completely missed it. I even missed the link buried in the wiki page because I only really scan through the APM wiki as I am more a copter person. I think these tutes should have their own sub heading in the flight mode section and APM & AC2 should both point to the same place for the tutes.


To the AC2 team, I do realise that AC2 is still young and the wiki is still very much in development.

3D Robotics
Comment by Chris Anderson on May 14, 2011 at 6:23pm
Gordon: Good idea. I've linked these tutorial in the APM manual, and linked to that in the AC2 manual, too. Please let me know if you've found some more that I should add.


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