Hello,
I am building a micro heli using a PixRacer, which only has six outputs. Is there any way that I can set the main ESC to channel 5 or 6, instead of channel 8?
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In 3.5 you can. Set the desired SERVOx_FUNCTION param to HeliRSC (31)
Ugh, you told me how to do that before, and I was messing with RC_MAP instead.
If I ever get this thing into the air, I will try to add a N00B point of view to the wiki.
Thanks!
LOL! It will fly. It will still look for the RC input for the governor/throttle to be on RC8. Setting the SERVOx_FUNCTION to whatever channel you want will do the mapping of the HeliRSC output to your selected channel. Since your Pixracer only has 6 pwm outputs, probably on 6. But you could do 5 if you want.
Make sure your SERVO1 ,2, 3 and 4 FUNCTIONS are set properly too, to correspond with the servo positions in the H_ params (SERVO4 is rudder, or Motor 4). If you have to reverse one to get the collective and cyclic to go the right direction you can use the SERVOx reversing param - 0 is ânormalâ, 1 is âreversedâ.
The main difference between 3.4 and 3.5 is that in 3.4 those SERVOx_ params used to be H_ params for heli.
Thank you so much. I know have a working swash plate with collective and cyclic going in the correct directions. It also responds correctly in stabilize mode, moving in the correct directions.
However, I cannot get the main motor to spool up. I get through the pre-arming checks okay, and hold the button (which is blinking red) until it goes solid red and get a satisfying beep. I can then arm it through MP, and it arms. Except, the main ESC is not working. I could move on and get it into the air if I could get it to arm!
Edit: I donât understand everything the devs are doing with RSC, so I set up my throttle curves on my radio (Taranis XD9 Plus). I verified that they are working on channel 8, and they do show up on the radio calibration screen when I move the throttle stick up and down.
Edit 2: HOLD UP. For some reason channel 8 isnât getting sent through my transmitter anymore. I need to figure this out.
There is RSC mode 1 (direct thru channel 8), mode 2 (governor on/off), and mode 3 (software V throttle curve).
If you are using mode 1 you will have to whip up a mix in your radio that ties the collective to a channel 8 output. And make sure you are not using a heli mix in your radio. Just use airplane mode, or some radios will allow heli mode with no CCPM mixing in the radio with âstraightâ or âdirectâ swash for a fixed pitch heli.
I finally figured it out! Itâs the E-Flight 2 in 1 ESC for the Blade 130S. I did some trouble shooting by hooking up a different ESC to channel 5 (which is what I mapped RSC to). The motor spun up just fine.
For some reason, it doesnât like the signals it is getting from the PixRacer and wonât arm. I tried operating it from a simple servo tester, and it wouldnât arm until I had both signal pins in place. But when I hook it to servo 4 (rudder ESC) and servo 5 (RSC), it will not arm.
I think need to get two small ESCs, one for the tail, and one for the main rotor.
Any ideas?
OK, so this is a direct drive fixed pitch tail? Or a collective pitch tail? If itâs DDFP thatâs currently broken in 3.5 but @tridge put in a PR to fix it
And I got a build here that you can install so it works properly until the fix gets into master and backported to 3.5
https://drive.google.com/open?id=0B5oLpNzxih4tRjRJbk91MUozdDA
Yes, you need an esc for the main rotor, and another for the tail motor. The tail motor signal comes from SERVO4 and be sure to set the H_TAIL_TYPE to 3 for DDFP. If the tail blows the wrong way just swap two wires from the ESC to the motor. Donât try to reverse it with the SERVO param - that wonât work to reverse it. That just reverses the signal to the tail ESC.
It is DDFP. That makes a bunch of sense now. I looked at the servo outputs on channels 5 (RSC) and 4 (rudder). The RSC is outputting 1000, and 4 is outputting 1500, meaning that it would have done pirouettes at zero throttle.
I will load this firmware and see what happens.
I honestly cannot thank you enough for the amount of time you have helped me and hope to pass it on!
AAAAAHHHH. I tried, but the board rejected the firmware. I guess that I am sunk for a bit unless I can find a work aroundâŚ
Edit: The firmware Tridge posted doesnât work with the Pixracer. I changed the servo 4 minimum to 1000, and now everything arms okay, but as you stated, the tail rotor spins up because the signal is passed through at 1500 from the transmitter.
I built in a kill switch on my transmitter that sends a PWM of 1000 to the main and tail ESCs. I am going to stick the tail rotor on it and see if stabilize mode will stop the tail ESC or not.
Thanks again for your help. I will be watching for the next version of Copter.
Yeah, hold off a bit on that. I forgot that build is for a v2 Pixhawk. I got the code in a different computer from where Iâm at right now, and the computer Iâm on doesnât have the tools to build it. Iâll build a v4 version for your Pixracer tonight and get the link to you.
You are the best. I am at least able to get it everything to arm, and operate in the proper directions, so I know it will at least work. Iâve never been so happy to have a heli spin around on my kitchen floor!
Alternative, if you want to try building it yourself this is my branch that has the DDFP tail fix code in it
https://github.com/ChristopherOlson/ardupilot/tree/pr-heli-DDFP-tail-fix
When you build it for a Pixracer use âmake PX4-v4-heliâ
The instructions on how to build are here:
http://ardupilot.org/dev/docs/building-the-code.html
Otherwise Iâll get a build done tonight and upload it for you.
Yeah, the stock code enables the DDFP tail without the controller even armed. I got a DDFP on my Trex 500 with a 9" prop on the tail and it was really exciting to fire that one up the first time and find out she was âhotâ as soon as I turned on the power 
I will gladly wait for your link. I will take a look at the how-to you sent me though.
A 130S whirling around your kitchen is âcuteâ. A T-Rex 500 is âterrifyingâ.
Dave, here is the link to the v4 build for your Pixracer
https://drive.google.com/open?id=0B5oLpNzxih4tdk9Mcm8yRFhibUU
I donât know if it was terrifying or not. Sort of like the kids at school playing âhelicopterâ with a jump rope. Except with a real one. With the trim at 1500 I couldnât believe how fast that thing could spin on the cement floor in the hanger. And it didnât start spinning right away. I plugged it in and got up and turned around it just took off.
I recommend setting the trim to 1000 because some ESCâs require that in order to arm themselves. The takeoff procedure with the firmware with the fix in it is that the tail rotor wonât start until the FC is armed and you raise the motor interlock on channel 8. The main rotor will start spinning up and bump the rudder to the right a bit to start the tail rotor. Once you get the PIDâs tuned it will throttle the tail rotor and hold the heading by itself on liftoff. Before you tune the PIDâs for the tail rotor you may have to play with the rudder a bit so it doesnât piro on liftoff.
Thank you very much!!
I uploaded it this morning, and as promised, channel 4 is not in DDFP ankle chopping mode. It now reads 1000, so the ESC will boot up safely. Hopefully I can start tuning and leave you alone!
Thank you so much for your help!