Wednesday, June 21, 2017

How I fixed my Cheerson CX-20 After Mission Planner Grounded Me

After many sessions with Mission Planner we were left with a drone that couldn't fly.
Someone suggested I needed to calibrate my transmitter.
  1. Drone weighted down during the throttle calibration process; no fear of a flyaway with that hunk of rusty tube threaded through the landing skids.
Calibration of the throttle completed and the rotors now seem to throttle up normally but after the session we check and find that the drone is still not able to lift into the air, so where do we go from here.

Our Internet browsing leads to this article which describes a familiar condition.

"CX20 not lifting off Posted by Rob Nielsen on February 20, 2015 at 2:15pm in QuadcoptersView Discussions I just got my CX20 yesterday, I have been reading up on all the details and quirks so I was ready for it's arrival. I did a complete inspection of the interior components (ensuring I had disconnected the magnetometer in the mast). Everything is secure and in it's proper position. all solder connections seem sound. APM and GPS are in place and secure (they are mounting the GPS on the opposite side from the USB now). I reassembled everything and reconnected the Mag. Checked the propellers for balance. By this tiem the stock battery on the stock charger was completely charged. I updated the firmware and made sure it knew where home is in the Mission Planner software, as well as did a full calibration of accelerometers, Mag and transmitter. Propellers on their proper arms. All set to go. Ok time to fly. I take the unit outside. connect the battery, switch on the TX. The system binds as it should. Everything seems good. I have a solid green (Sats visible). I unlock the motors and try to take off. the moment the throttle leaves the full off position, the motors kick in at moderate revs, not enough for liftoff but flattening the grass. The unit leans forward so i pull back on the cyclic (right stick) to compensate. As i rev to max throttle, there is not difference in the RPM of the motors. At 0 throttle it is off, at 1% and up it is at a fast idle, not enough to take off. If i move the cyclic, i can rock it side to side and front to back, but it doesn't have the power to liftoff. similar to and ICE with the choke applied. I have gone through every permutation of the calibration routines from the incorrect factory ones to the ones used by people who fly this unit successfully many times over. I tried the all at once ESC calibration but this seems to not be the APM that works with that method. The only thing I can think of is doing a manual 'one at a time' ESC calibration but at this moment I am waiting for word back from the supplier. I have been waiting for a while for this to show up and now I am waiting with the thing right in front of me. it's pretty frustrating as you can imagine. Great weather and I can't fly it. FPV and telemetry gear on the way for it. ARG! If anyone has some good suggestions, i am VERY eager to try them. Flying the little Walkera and the Syma is getting old.

Suffice to say that I have been having this very same problem and I could not have explained it any better myself. It has been a very frustrating series of experiences that I have been having ever since I became risky soul  by updating firmware for my drone using the Mission Planner Graphic User Interface (GUI). Those sessions left my Cheerson CX 20 with Throttle settings of 80 when the default value should be 1000, rendering it incapable of flight. Several flip-overs later the USB port has been damaged will no longer talk to my computer so you can imagine how excited I was to discover this YouTube video which carefully explained how to re-calibrate the drones throttles using only the controller (transmitter). In my case I didn't even have to remove the blades; I simply slipped a heavy length of steel through the landing skids and carried out the procedure exactly as explained in the video."

The problem still persists, I have tried everything I can think of. I have downloaded the factory settings, firmware and computer drivers but am reluctant to do it since the instruction video is in Chinese.

One more thing to try before I bite the bullet and try blindly to upload these files.

Lasse Lundberg says on February 26, 2015 at 3:05pm : "Your esc's are probably not calibrated, I go into mission planner, in the full list there is a setting that says esc calibrate and you can choose to enter calibration on the next I set that, write parameter, disconnect, unhook battery, take props off, move throttle on transmitter to max but keep it off, hook up battery to copter and quickly turn on transmitter. mine will beeb a few extra times than it normally does, i then lower throttle to minimum. disarm, unplug quad, and turn of tx....turn everything back on and see if the motors spin up like they are supposed to, then mount props and see if it will fly?"
The answer of course it would not.

Here is another |Guy who claims he has the answer.........maybe it's worth a try.

Reinstalling Factory Parameters on the Cheerson CX-20/Quanum Nova By: Joey Mirabelli:  "You disconnected while calibrating in Mission Planner and now your CX-20/Nova is stuck like this?

Follow this tutorial to solve the above problem or to just restore to factory settings

STEP 1: Download this file and save it somewhere that is easy to access, like the desktop. We will be loading this into the quadcopter shortly.

In case this link disappears sometime I have the file saved in the cloud for downloading here

STEP 2: Plug a Mini USB (OR power up the telemetry) into the belly where it says "USB" and then plug in the battery.

STEP 3: Plug the other end of the USB into the computer and start up Mission Planner.

STEP 4: Click the connect button on the top right and allow it to connect.

STEP 5: Locate the CONFIG/TUNING tab at the top and then click "Full Parameter List" on the left.

STEP 6: Click "Load from file" on the top right and select the file we downloaded at the beginning of the tutorial.

STEP 7: Select "Write Params" and wait 20 seconds. Then click the disconnect button at the top right of Mission Planner. The quad is likely still beeping at this point.

STEP 8: Once you've clicked "Disconnect" and have waited a few seconds, unplug the USB from the computer, unplug the battery from the quadcopter, then unplug the USB from the quadcopter itself.

STEP 9: Plug the battery back into the quadcopter to confirm that the consant beeping has stopped. DO NOT GO AND FLY YET.

STEP 10: Now you must go through the calibration wizard. This is a crucial step."

Mission Planning in my opinion is a complete disaster. I now wish that I had never heard of the program.....I should have left well enough alone and stuck with the factory settings. 

Mission Planner behaves differently each time I use it; sometimes it will connect and other times it will not, no matter how many times I try. The screens are nothing like what others tell you, for example I could never find options like  "Full Parameter List" or "Load from file" no matter how many times or versions of the program that I tried.

The last time I used Mission Planner these were the two setup pages that were displayed:

 If I were a conspiracy plan believer I might say that this would be a clever plot to render millions of camera drones useless and grounded forever: simply make the default maximum throttle parameter 200 (in my case 80) when it would normally be 1000 and none of them would ever fly again.

The key to fixing the throttle problem is found in this video.

Link to video showing how to back up and install firmware using Mission Planner

Complete guide to CX 20 Calibration and Binding:

Perhaps I was a little harsh with my comments on Mission Planner, I can now find the options mentioned above after discovering the Layout Button which when pressed uncovered the Basic/Advanced option.

Screen shot of Mission Planner screen that shows where options to list all parameters shows up.
THR_MAX at the bottom of the list of parameters was changed from the default of 80 to 1000.
THR_MIN was changed from 250 to 0.

These parameters were written to the drone and arming was tested but failed to unlock the motors.
At this frustrating point it was time for a break to and wait for further inspiration.
I remembered the Arming Check; a series of check boxes requiring a tick to include a particular arming condition. Maybe this is why the drone isn't arming? When I got around to looking for it, it wasn't showing up any more. Perhaps we have to go back to Basic option before the check boxes will show up?
Changing the Advanced Layout back to Basic and re-clicking the CONFIGTUNNG icon Standard Params the page we are looking for suddenly appears. Then we notice that the All box has been selected, which confirms our suspicion on why our drone is not arming. After on-checking the All box and writing the parameters we are anxious to see if the drone will arm and........Surprise surprise! the drone immediately arms and the motors unlock on command.
  The motors respond with full range throttle as they did when it was new. Now we are anxious to put it back together and see how it will fly.

Finally a taste of success after being grounded for over a year; downloading and installing factory parameters proved to be the key to success.

In Conclusion: I now think the flawed parameter files found in Mission Planner are not the result of some conspiracy, but rather the work of a few malicious individuals (who else would create files where maximum throttle is of a lower value than minimum throttle) hoping to lure as many drone newbies into loading their tainted parameter files and sit back and watch the havoc created; in much the same way that hackers operate. Everyone using Mission Planner to update their drone's behavior should be aware that tainted files exist and exercise extreme caution when attempting to load a new parameter file.



  1. i used mission planner now i have no Pitch control at all !!
    a bit like your throttle i presume , I have a flysky remote and receiver on order will be interesting to see if it is the same as i am pulling my Hair out trying to get this drone to work ..

    1. Yes! It sounds like the same sort of problem, you just have to be persistent and and adjust the pitch to your, desired amount in the full parameters list or download the default settings as I discuss in the blog page. Hope this helps!