AR7200BX DSMx issues.

I think I've run into an issue with running DSMx. Vitals:

Devo 8S, Nightly build deviation-devo8-e05abdefdc9d.dfu
AR7200BX
1 DSMx Sat
3x Align DS515m and 1 x DS525m
Powering off 5V BEC

I created a very simple 6ch AR7200bx compatible model config following the directions in the FBL setup sticky. 1 servo, all channels giving linear output with a linear pitch and throttle curve. The only other settings are for the gear channel values and the throttle hold. I just wanted something super simple for servo setup.

I was able to bind in DSMx mode using the normal bind procedure but wasn't getting any real servo response, just some twitching from the cyclics and very very delayed inputs on the rudder channel. Using the gear channel tho I was able to confirm that they were indeed talking because it would switch from HH to rate correctly. I can take a video if needed. Also, the channel inputs and outputs from the mixer are correct looking.

So I got frustrated and decided to give DSM2 a try. Re-bound the Ar7200bx in DSM2 mode and right away I'm getting correct servo action and everything's acting correctly just like it should.

I tried swapping back and forth a few times and the DSMx behavior was consistently wrong. I'm going to move forward with setup in DSM2 mode for the moment but any thoughts or advice would be helpful!

How about with no sat plugged in? Just the ar7200bx alone.

Behavior is the same without the sat. I've noticed that the only servo that seems to be "responding" is the ELE servo. It seems to respond roughly correlating with the THR/PIT channel however it seems to do it on about a half second delay so I move the THR stick and a moment later the servo moves some. Also when the THR is not all the way down the ELE/AIL stick will produce some twitching in the AIL/PIT servos.

Have you tried selecting different number of channels? 8 rather than 7?

Hexperience wrote: Have you tried selecting different number of channels? 8 rather than 7?

Ok that did the trick. I switched to 8CH and re-bound in DSMx mode and everything worked as expected.

Any ideas as to why 8 vs 7 makes such a huge difference? Would it be a good idea then to make 8CH the default for DSMx or is this a AR7200bx specific issue?

Not sure why, but I know the guys are working on a few things in the dsm area, regarding telemetry. Might be worth posting the issue in bit buck so it gets addressed before 3.0.

If it's specific to the ar7200bx then I don't think the default needs to be changed, but if PB and Vlad start looking into it, they may find that it does make more sense to set 8 as the default.

Good idea, I'll go ahead and post up the issue.

Hi guys... I'm getting my AR7200BX back from horizon hobby on Monday and wanted to confirm..

With deviation 3.0, ar7200bx, dsmX mode set to 8 channels we will get 11ms working correctly right?

Thanks.

So setting my tx to 8 channels dsmx it should work fine right?

I'm having a problem setting up my AR7200BX in my Devo 8s. I used the standard GUI for the setup, and also used the 6 ch heli template. I selected DSMX, and 8 ch on the main page. All servo's, and functions work properly except THR. The heli won't spin up. I'm using TH on the RUD/DR switch. One other thing is that on my DX6i I have the PIT servo reversed. In the Devo 8 I have it set to normal to get the swash to move up.
Any ideas?
I think it might have to do with ordering the channels, but I can't change the channel order in the standard GUI.

vlad_vy wrote: I think that now it will be fine with both 7ch and 8ch mode, if you don't use telemetry (by default DSM telemetry = Off). If telemetry = On, with AR7200BX will be better use 8ch mode.

But there is no 11ms mode right? No matter what combination of channels or telemetry on/off?

clearprop88 wrote: I'm having a problem setting up my AR7200BX in my Devo 8s. I used the standard GUI for the setup, and also used the 6 ch heli template. I selected DSMX, and 8 ch on the main page. All servo's, and functions work properly except THR. The heli won't spin up. I'm using TH on the RUD/DR switch. One other thing is that on my DX6i I have the PIT servo reversed. In the Devo 8 I have it set to normal to get the swash to move up.
Any ideas?
I think it might have to do with ordering the channels, but I can't change the channel order in the standard GUI.

Channel 1 is throttle on your config right? Post your model.ini file. I have mine working (as much as the 300x "works"). If you really need it I can post my model.ini file, but would prefer to get yours working.

Here's the .ini file.
name=TREX 450 PRO RJX BX@
mixermode=Standard
icon=HELI.BMP
[radio]
protocol=DSMX
num_channels=8
fixed_id=123456
tx_power=1mW

[protocol_opts]
Telemetry=Off

[channel1]
safetysw=!RUD DR0
safetyval=-110
template=complex
[mixer]
src=THR
dest=Ch1
curvetype=9point
points=-100,-60,-18,9,28,46,62,75,85
[mixer]
src=THR
dest=Ch1
switch=FMODE1
curvetype=9point
points=-100,80,80,80,80,80,80,80,80
[mixer]
src=THR
dest=Ch1
switch=FMODE2
curvetype=9point
points=-100,-75,-50,-25,0,25,50,75,100

[channel2]
template=cyclic1

[channel3]
template=cyclic2

[channel4]
reverse=1
template=expo_dr
[mixer]
src=RUD
dest=Ch4
curvetype=expo
points=0,0
[mixer]
src=RUD
dest=Ch4
switch=GEAR1
curvetype=expo
points=0,0

[channel5]
template=expo_dr
[mixer]
src=MIX0
dest=Ch5
scalar=30
curvetype=fixed
[mixer]
src=MIX0
dest=Ch5
switch=GEAR1
scalar=-60
curvetype=fixed

[channel6]
template=cyclic3

[virtchan1]
template=expo_dr
[mixer]
src=AIL
dest=Virt1
curvetype=expo
points=0,0
[mixer]
src=AIL
dest=Virt1
switch=AIL DR1
curvetype=expo
points=0,0

[virtchan2]
template=expo_dr
[mixer]
src=ELE
dest=Virt2
curvetype=expo
points=0,0
[mixer]
src=ELE
dest=Virt2
switch=ELE DR1
curvetype=expo
points=0,0

[virtchan3]
template=complex
[mixer]
src=THR
dest=Virt3
curvetype=9point
points=-35,-20,-13,-5,0,25,50,75,100
[mixer]
src=THR
dest=Virt3
switch=FMODE1
curvetype=9point
points=-40,-30,-20,-12,0,25,50,75,100
[mixer]
src=THR
dest=Virt3
switch=FMODE2
curvetype=9point
points=-100,-75,-50,-25,0,25,50,75,100
[mixer]
src=THR
dest=Virt3
switch=!RUD DR0
curvetype=9point
points=0,0,0,0,0,25,50,75,100

[trim1]
src=LEFT_V
pos=TRIMLV+
neg=TRIMLV-
[trim2]
src=RIGHT_V
pos=TRIMRV+
neg=TRIMRV-
[trim3]
src=LEFT_H
pos=TRIMLH+
neg=TRIMLH-
[trim4]
src=RIGHT_H
pos=TRIMRH+
neg=TRIMRH-
[timer1]
type=countdown
src=Ch1
time=270
[timer2]
src=Ch1
[safety]
Auto=min
[gui-qvga]
trim=4in
barsize=half
box1=Ch3
box2=Timer1
box3=Timer2
bar1=Ch1
bar2=Ch2
bar3=Ch3
bar4=Ch4
toggle1=ELE DR
tglico1=0,1,0
toggle2=AIL DR
tglico2=0,0,0
toggle3=RUD DR
tglico3=0,2,0
toggle4=GEAR
tglico4=0,4,0
quickpage1=Telemetry monitor

The only thing I can think of is that the AR7200BX thinks your throttle is not all the way down when you start up. Maybe it has something to do with your hold being -110 but your curves are all at -100. It may be confused about the throttle range.

Try putting your safe value back to -100, then set the "Scale -" value to -110. If that doesn't do it, try a little more.

The other way would be to set safe and scale values to -100 and re-calibrate the throttle, not sure of the procedure for it off the top of my head.

Is your ESC arming correctly? I had to use a TH value of -103 to convince my ESC to arm through the AR7200BX. -100 would work fine using a seperate RX but for whatever reason the AR7200BX wanted -103. Also have you set up your ESC throttle range? The failsafe to prevent hot starts on the AR7200 also means you have to finagle things to get your ESC into programming mode.