Issues with DSMX?

I encountered some strange issues here with my KingKong 90GT (with DSMX receiver) and my Devo 10 (with 4-in-1 module and Deviation nightly build 2017-04-04):

The quad seems to have 'hiccups'. The motors stop every few seconds in mid-air and the quad does not respond to TX input then for a moment - that's just for the fraction of a second (maybe 0.25 sec). It's very annoying

Distance doesn't matter - it happens right in front of me or 50 meters away.

I tried to increase the TX power to 150mW but that made it even worse, the quad then just drops out of the sky every few meters. More TX power seems to double the duration of those blackouts.

Is this an issues with Deviation and the DSMX protocol? Or are there any settings / adjustments I could try to get rid of this?

In BetaFlight, the RX is set to "Spektrum 2048" (1024 refuses to bind) and RC interpolation to "Auto". Telemetry is off, UART2 set to "Serial".

The Devo 10 model profile is set to "8 channels" ("7 channels" refuses to bind), all DSMX protocol advanced options (filter, telemetry, OrangeRX etc.) are off.

Anything I could try here? Are there any improvements to the DSMX protocol in the latest nightlies?

My kingkong 90gt gave me nothing but problems on dsmx. Bound in dsm2 and not a single hiccup.

This was with a devo7e on stock module and 4in1 module. Dsmx on my kingkong 90gt would result in laggy response and range issues.

Dsm2 has no issues. As far as my kingkong is concerned, it actually only can be reliable in dsm2 mode. Even setting rx serial to spek2048 and binding dsmx did not alleviate the problem.

Spek1024 and binding in dsm2 seems to be what my receiver is actually operating under.

I also use dsmx satellites (lemonrx and redcons) with no issues. I am using vlads builds.

I'm sure you can bind in dsm2 and if you can that should resolve your issues.

I tried to bind the receiver that comes with the GT90 in DSM2 mode first, but it refused to bind. Then I tried DSMX and it worked instantly (but with hiccups). Maybe it refused to bind in DSM2 mode because the receiver type in BetaFlight is set to Spektrum 2048?

So you successfuly managed to use DSM2 protocol with the stock receiver? Are there any special settings (on the Devo or in BetaFlight) to keep in mind when trying DSM2 with the GT90?

Yes I use dsm2 exclusively on the kingkong 90gt. I was able to bind in dsmx but too many problems came around.

In betaflight before you try to bind set the serial protocol to spek1024.

In your tx make sure you are on dsm2 protocol. I bound in 7 channels on the tx and all 7 are recognized on the kingkong.

When I get back home I can take a snapshot of my betaflight settings for the rx and send them your way.

Whatsinaname wrote: When I get back home I can take a snapshot of my betaflight settings for the rx and send them your way.

That would be of great help, thanks!

With DSMX (Spektrum 2048) all channels work perfectly for me - at least in BetaFlight. But there are constant micro blackouts / hiccups / whatever-it-is every few seconds during a flight. That's pretty annoying.

If there was a change log for the nightly builds I'd know if it would be worth to upgrade to a newer nightly (in case the DSMX support was improved). But without any change logs available it's just a random shot

Whatsinaname wrote: I bound in 7 channels on the tx and all 7 are recognized on the kingkong.

So only 7 channels to use then? Hm, that's a little downer since I am used to 8 channels (one for arming, one for flight modes, one for the buzzer and one to switch LEDs on and off). So I guess I'll go without the LED switch then...

Kingkong 90gt betaflight 3.1.6 - I still have to update it to the latest.

Uart, configuration, and rx tabs

I held the sticks and moved one of the aux switches to low position for the screenshot

Thanks a lot!!

Switching to DSM2 instead of DSMX indeed seems to fix the issues. Did a short test flight with no problems at all. No stuttering anymore.

However, I wonder if it's the receiver that is not compatible with DSMX - or Deviation compatibility issues..?

It's the receiver that is not dsmx compatible even though the kingkong says dsm2/dsmx. I know the reason too.

As far as deviation and dsmx...there is no issue (at least with vlads builds) where latency and range are concerned. It actually does work.

I use dsmx with my lemonrx and redcon satellites all the time on my 200+ sized quads. Haven't had a brown out yet except for the issues I had when using the nightly build.

I also have a makerfire inductrix flight controller that states dsm2/dsmx compatible but refuses to work correctly in dsmx mode even with my dxe or dx6e. Dsm2 has to be used.

I believe the reason these receivers are stated as dsm2/dsmx compatible is because genuine spektrum tx's (most of them and not including the dxe) are "supposed" to be able to auto negotiate the protocol specified by the rx. The dxe only binds in dsmx...no dsm2 capability. The dx6e is "supposed" to be able to bind in dsm2 mode based on the rx but I have seen otherwise.

Enter the devo7e where I was able to actually switch to dsm2 and my rx issues disappeared. On the makerfire and kingkong these scenarios are repeatable. Bind in dsm2 and fly with no issues. Bind in dsmx and I get brownouts and range dropouts. This is testing power from 10mW up to 150mW...dsmx on these two setups just does not exist.

That's interesting to know - thanks for sharing your experience! Your help saved me lots of headaches

I too am having issues with dsmx range. Last wednesday I almost lost my Trex 470L, it went into fail safe due to lost radio signal, according to Brain 2 log. It was only about 30 meters away, horzontal distance, from where I was stood and 10 meters high up. Luckily the heli floated and at about 5 centimetres from the ground, the motor started spooling, I have very slow spool up so wouldn't have helped, as it regained radio connection but I hit throttle hold and auto rotated as I didn't want too much energy to be left on the blades as it was going down. Landed gently no damage at all. I am using two Lemon Rx satellites with diversity antennas on the 470 so it shouldn't be anything to do with radio shadowing.

When I put the Devo 10 into range test, I can see the receiver lights start flickering even though I am only a meter from the receiver. At 24 paces, the receiver light completely goes off meaning signal completely lost. I have two LemonRx sats on my other heli and they do the same thing. I also have a spare OrangeRx full range diversity receiver and it also does the same thing. I have a OrangeRx simulator dongle, on the PC, and it does the same thing too. So this means that the Tx is at fault.

Can someone direct me to where I can download vlads build so I can test that? As I read that he fixed the dsmx range issues?

www.deviationtx.com/forum/builds/6407-de...-protocols?start=200

@denis747

Try giving the tx and the rx a bit of time to complete their pairing. My behavior with the devo7e is to load my model and wait a couple of seconds before I power up my quad. Then I wait again for the tx and rx to pair before I use the sticks to recalibrate my gyro and accelerometer.

Once the calibration is complete (led blink verifications) I fly with no issues.

I do this on my spektrum and flysky gear too.

Thanks. I think I already do that as by the time the Brain 2 FBL does all its self checks and initialises by giving 3 pitch pumps, the Tx and Rx should have had enough time to pair properly. I have installed one of the nightly builds which I hope will solve the problem.

I'm having the same issue with my setup... not with the 90GT, but with F3 brushed boards and redcon Rx, devo7e with 4in1

I'l have to give this a shot and hopefully it helps

To be honest, these issues have made me not to trust this Tx to fly my Trex 470L anymore due to the random drop outs. It is dangerous flying a heli of that size with an unreliable radio link. In the mean time, I have ordered a new rf module for the Devo 10 and hopefully that should improve my 24 paces range test. If not then time for a new different Tx.

@denis747

Have you used your dsmx rx's with any other tx? It sounds like you are mostly a heli flyer.

Where are your receivers located on your rigs? Carbon fiber (true cf as there are knock off cf parts) is notorious for rx signal breakup, disruption or blockage which could lead to dropouts of signal.

On all my 200+ sized quads my dsmx diversity satellites are mounted as high up as possible with antenna mounts that direct the antenna wires up and away even more.

Take a look at this link
www.gearbest.com/brush-fpv-racer/pp_609677.html

That is one of the kits I fly. At the rear end you will see two antenna tubes sticking up and out. It is also mounted above the cf plate (where all other electronics are sandwiched inside). I fly that kit with my devo7e with the 4in1 module and a redcon dsmx satellite and I have no issues or worries flying even at full range distance.

Also, let me know if you do plan to get rid of your devo10 as I wouldn't mind acquiring that tx. I have an extra 4in1 module (ordered one too many by mistake) that I would put into it. I am really interested in how it feels compared to my 7e. My 7e is the perfect size for my hands which is why I use it exclusively now.

Whatsinaname wrote: @denis747

Have you used your dsmx rx's with any other tx? It sounds like you are mostly a heli flyer.

Where are your receivers located on your rigs? Carbon fiber (true cf as there are knock off cf parts) is notorious for rx signal breakup, disruption or blockage which could lead to dropouts of signal.

On all my 200+ sized quads my dsmx diversity satellites are mounted as high up as possible with antenna mounts that direct the antenna wires up and away even more.

Take a look at this link
www.gearbest.com/brush-fpv-racer/pp_609677.html

That is one of the kits I fly. At the rear end you will see two antenna tubes sticking up and out. It is also mounted above the cf plate (where all other electronics are sandwiched inside). I fly that kit with my devo7e with the 4in1 module and a redcon dsmx satellite and I have no issues or worries flying even at full range distance.

Also, let me know if you do plan to get rid of your devo10 as I wouldn't mind acquiring that tx. I have an extra 4in1 module (ordered one too many by mistake) that I would put into it. I am really interested in how it feels compared to my 7e. My 7e is the perfect size for my hands which is why I use it exclusively now.

Thanks. To be honest, the only drop out I had was when using Deviation 5.0.0 at about 30 meters away from me. The heli went into fail safe and luckily floated down, from 10 meters up and landed gently on the skids without any damage at all. I installed one of the Nightlies and switched off the OrangeRx option. Due to unsuitable weather, I flew the heli once with the nightly deviation in the Tx but I was afraid to take it far away just in case, as it lost radio link once before with the previous Deviation 5.0.0 and also after reading about other people having drop outs.

The heli is an Align Trex 470LP with two LemonRx diversity antenna satellites mounted on each side. The worrying issue for me is that when I put the Tx into range test mode, I only get up to 24 paces and I loose signal after only 24 paces. I would be happy if I got 30 paces at least. I also did a test inside my house with the Tx upstairs and I placed it into range test mode. I have a spare OrangeRx long range diversity Rx with a non diversity spare LemonRx sat connected to it and when I did a test they all lost range at about the same distance as the two Lemon sats on my heli so I don't think those sats are bad. I am thinking it is a slightly weak RF module in my Devo 10. I have ordered a new one which should come next week and hopefully I should get more than 30 paces in range test mode.

Here is how I have the two sats mounted on my 470

Left side satellite



Right side satellite

I would try to get the antennas away from your cf plate as best as possible. I see you used some kind of material to act as a barrier but you never know until you try. I also understand space may be at a premium on a heli rig.

I printed a bunch of these for my satellites
www.thingiverse.com/thing:2073912

My redcons and lemonrx's can hold signal to my 7e when I leave the tx in the garage and walk to the other side of the second floor with my quad armed and motors spinning at idle.

Another thing i would try, if you can, is let your recievers dangle from your rig while you walk it around and see if you still lose signal.

I am really just trying to help you sort it out.

Thanks, I will re position the antennas and try move them further away. Also the new RF module should arrive next week and hopefully should improve things.

I have been having similar problems on dsmx on a few of my models with redcon receivers some seem to work great on dsmx others are just getting constant dropouts the worsted destroying a helicopter build. The sat receivers seem to work fine on their own but the main ones some suffer some don't. After reading this I'll try dsm2 on the dodgy ones

Try vlad's builds. My Devo 10 was flakey as hell bound via DSMX to a Lemon DSMX diversity receiver. Range issues as described... blinking light even at 1m. It worked fine with an Orange R111Xn and with any sat on DSM2.

But those problems went away a few months ago when I used vlads builds. Until his mods the Devo only supported 22ms. (Which is why I eventually bought a DX9). Now I have 11ms and expected range with the same sat that was so problematic previously.