Tuesday, February 23, 2016

Quanum Nova & Cheerson CX-20 (Open Source APM-FC version) - Tech Addendum

As you know, most of my posts here are about my experiences with my Quanum Novas (a clone of the Cheerson CX-20 with the same Open-Source APM Flight Controller). Please search this blog (top left) if you are looking for something specific. This post will hold summaries and misc info that hasn't been posted before about this quadcopter. It will likely be added/edited frequently.

Verified as Working Custom Firmwares:
These are verified by me to work. I think pilots should be reminded that even if a posted archive is described as being some ArduCopter version, don't assume all posted custom-hex firmwares on the Internet are the same (chances are 99% they are not ... due to custom code changes and compiler settings).

v3.1.5 - VinnieRC's Custom ArduCopter v3.1.5
- http://www.rcgroups.com/forums/showpost.php?p=31678509&postcount=24678

(Original posted archive holding ArduCopter.3.1.5-quad-apm2-CX20.hex)
MD5 Checksum: A24C2871AE252108E5B24D9BC438D2A8
SHA-1 Checksum: 568BC233BAFDD94CB903D2ED166B8379CB88589A
Generated by MD5 & SHA-1 Checksum Utility

MD5 Checksum: 9C124499E57906CC6F4FF4060290B66F
SHA-1 Checksum: 143EEC489C451832F33C75D6EBA7CAE3F5A60B71
Generated by MD5 & SHA-1 Checksum Utility

This specific v3.1.5 works fine (including data-flash memory and logging feature) on two different versions of Cheerson installed APM-FC (in my Quanum Novas). Since my quads are working, I haven't found a need to look at the actual source-code. However, if the source-code was different (from any other posted archive) it would not pass MD5/SHA-1 verification.

- http://quadcopter-robotics.blogspot.com/2015/05/upgrading-firmware-to-315-cheerson.html
- http://quadcopter-robotics.blogspot.com/2015/09/new-nova-modding-for-flight.html

v3.2 - v3.2.1 - If I ever eventually get around to doing something with 3.2 or 3.2.1 , I will post it here also. If I do run v3.2.x, I will likely pro-actively reduce the logging to help ease the demands on this little APM-252 ... to prevent it from becoming over-burdened by the more complex code (as compared to v3.1.5). See above links for a couple of 3.1.5 setup-guide posts.


Looks like either Cheerson or GlobalFly actually designed this little APM_v2.52 FC and shared it with the other. Here is a manual that GlobalFly released. (Thanks to RobotShop_com and DKEmxr for finding it).


I've never owned a the RTF version (with the stock white radio gear pre-installed) but these pics might be helpful to some pilots. Thanks to PietPech.

This next pic applies to all models (including PnF)

Another drawing of stock radio connection.
Finally, a pilot's pic from the forum.


  1. Hey Tesla, quick question. Are you still in custom 3.1.5? If yes, why? Also do you have a minimosd installed? Was it easy?

    1. Just because it works fine for me. Don't really have time to lately to install v3.2.1, calibrate, tune, test, etc ...
      No, no MinimOSD yet.

  2. Hello, i tried the 3.1.5 and it works much better tha 3.2.1 (latest) in which althold is buggy. However, in the abive 3.1.5 i am unable to read logs using either MP or ApmPlanner. I have sure turned on the log bitmask but the GCS are simply unabke to read the logs. Any idea why?

    1. Logs aren't created or MissionPlanner can't read them? Do they look ok when you open them with Windows NotePad or similar ? (they are just ASCII files) If not created, is your Log Bitmask saving or "sticking" properly (inside the FC)? You are downloading them with Terminal, right?

  3. I think logs are not generated at all. Not files in FC at all..

    I tried restarting quad and MP and after reading values MP shows the correct bit mask.

    No, i did not try downloading through terminal.. Only tried MP and ApmPlanner GUI.. And they cannot see any logs in FC. Do i have to use terminal? Why? How?

    Thanks for ur kind help..

    1. I've just always used Terminal in v3.1.2 and v3.1.5. I also use an actual USB cable.

  4. Great post and blog too. I have question.
    How can i connect my gimbal to apm? I have stock 2.52 apm on CX-20 and storm32 3axis gimbal. When i connect gimbal signal's to bottom connectors all work perfectly and i can control gimbal whit my CX-20 remote controller but i cant see anything in mission planner. I want that mission planner can control my gimbal (region of interest - pitch).
    Question is how can connect gimbal signal to RX and FC same time?
    Can i parallel connect (thru Y or T one pin signal cable) my gimbal to RX and APM same time?
    This is my default connections to APM and RX. Thx for advices.

    1. You have to pick one-or-the-other for control.

      I connect mine to radio. Works fine for me because I only use Taranis controls to level camera or point down sometimes. Mainly, I just want the gimbal to stay level with horizon.


      I've seen those controls in MP, but have never used them.

  5. Hi,
    I'm using the PNF Quanum Nova with open source controller from HobbyKing with a Turnigy i10 Transmitter (or the 9X).

    I have followed your helping instructions and succeed to have everything calibrated and working. Everything seems OK in the mission planner, GPS and other sensors, TX&RX channels etc...And yet, one final but critical step doesn't work: I just can't arm the motors! No error or any message, the screen just shows "Unarmed". I'm sure it is just a small forgotten step somewhere but still I can't find it.
    Please help.

    1. Is everything set for Mode-2? Is (left stick) throttle not reversed? Try while connected to MP. An "arming error" message should appear in main HUD, or I think there is a "Messages" tab or similar. Try outside on porch so GPS will get fix and DHOP will be 2.0 or better.

    2. I can see that all the channels are set correctly, each stick is showed correctly in the radio calibration screen, including the throttle. I also tried to arm the motors outside after I got the green GPS LED stable. I also tried different flight modes...
      How can check the DHOP? Is green LED not enough?

    3. Green light just means you have some kind of GPS-Fix, but HDOP might be too high. Satellites and HDOP shows in at bottom of MP main map-screen.

  6. Hi,
    The best HDOP I could mesure (in my garden) was 2.0-2.1 and I could not arm the motors. I tried on different flight modes with same results.
    I tried then on the roof (6th floor) and yet unsuccessfully. Unfortunately my laptop has no battery so I'm not able to mesure the HDOP there. I'll try to find an Android app that can help and I'll keep you posted.
    It seems to me very wiered that the quad prevent me to arm the motors on Acro mode because of the GPS signal...
    Thank you.

    1. Be sure GeoFence is OFF. You can try lowering DHOP Arm requirement to 2.2 (GPS_HDOP_GOOD,220) or 2.3. Use laptop with lawn extension cord to porch or roof.

    2. Good GPS Android app is:

  7. FYI, I was trying to configure PPM with my Cheerson CX-20 on stock 3.1.2 firmware and could not get it to arm like someone else mentioned above. Updated to 3.2 in Mission planner and had success. Tested POSHOLD and ALTHOLD field last night and was very stable. I have two of the Cheerson APMs so I can still compare a "stock" flash to the modified. (1st CX-20 didn't last long due to bad tx/rx and very questionable soldering)

  8. Hello,
    can you help me please with following question:
    Im using a CX 20 open source
    I connected a single servo on port "G +5V S2".
    I can control the servo, with my remote control - no problem.
    Now I want to control the servo with in planned wayoint mission by mission planner.
    How I can adress the servo within mission planner? Can you give me please a hint?
    Thank you very much.
    BR Alexander

    1. I've never done that, but sounds cool. If you figure it out, let us know. I have to manually control the camera pitch myself with the radio during missions.

  9. I am new to quadcopters. My recent prototype worked, but it hit a tree and got damaged. Do you have any suggestions for a replacement? I found some unique designs here: http://mydronelab.com/accessories/diy-quadcopter-kit.html


The stupid spammers have now forced me to approve each Comment before it appears (but I am usually pretty quick about it).