3D Robotics

3689600537?profile=originalI just got a Quanum Nova, which is a fantastic APM-powered copter that in many way outperforms the DJI Phantom for less than $300.  Although it's capable of full autonomy, just like any other ArduCopter, the one thing it's missing for easy field mission planning and DroidPlanner compatibility is telemetry. 

In this great tutorial, Jean-Louis Naudin shows how to add that:

Here an explanation for connecting the real time telemetry to the CX-20 or to the Quanum Nova

The telemetry port is located on the I/O board of the APM (the second board at the bottom and pluged to the main CPU board) where all the I/O plug are connected. The telemetry port is fully compatible with all the telemetry transmitter (3DR and all the compatible boards) and also with the Bluetooth boards commonly used with the APM boards.

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Below the pinout which shows the telemetry port I/O (back to the I/O board).

Note from the comments: depending on which radio you're using, you may have to reverse the TX and RX lines. Dmitry in the comments reports: "You must connect RX from the radio to TX on the APM! And vice versa for Radio TX. So I've changed green and yellow wires and it works!"

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sold 4 cables on the telemetry ports alt textthen protect the connections with hot glue alt text

Check the functioning alt text

The 4 pins telemetry plug is installed on the back of the fuselage alt text

Check the connection (at 57600 baud) with the mission planner or the Droid Planner 2 alt textalt text

Then, you may enjoy to use the telemetry... alt text

NEXT CHAPTER: Full autonomous mission with the Cheerson CX 20


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  • Hi !
    Just for Info: In case you upgrade the firmware and use Telemetry, you will likely end up with a broken mavlink connection "No heartbeat received" -

    The problem is that the original APM firmware of the cheerson was modified and they use RX2/TX2 for Mavlink. After upgrading to a later version, telemetry does not work directly. If you want to use a reasonable new firmware, you have to flash the following firmware - i've just tested it and it works great ! - Maybe worth adding to the tutorial.

  • 3D Robotics


  • Here is one of the post that talk about telemetry hack ScottFlys' mini how-to for Telemetry on CX-20

    Here is one of the post that talks about how to do it for the Nth times from Dogdude Dogdude's telemetry hack

    Just be careful if you don't have a good Weller solder.  You don't want to burn your IC on the board.

  • Here is the link to the thread, but this has been mentioned many times in multiple post so use the search function on the forum.

    RCGROUPS Forum for CX-20 Cheerson Auto Pathfinder

  • 3D Robotics

    Thanks, Vinnie. Do you have a link to the thread on RC Groups that shows which resistors to resolder? 

  • I am surprised people are still talking about firmware and telemetry here.  Folks please go to rcgroups.com and read up on it there.  We have had the solution for telemetry by resoldering to resistors and have been on 3.2 firmware since beta and now on RC and telemetry had been working.

    @Matt Elias, you know you can actually use Mission Planner to download firmware from your FC without having to mess with AVRISP MKII or like.

  • Thanks Guys,

    As I already have a spare APM 2.6, I think I will just swap it out for now. Having said that,my search will continue for the CX-20 original firmware HEX file.I contacted CX Hobby ( manufacturer ) and requested firmware. Fingers crossed. Thanks again PF and Matt for your input.
  • Mister T, you need a device like a AVRISP MkII or AVR Dragon or I believe this from Pololu should work too. I have not done it myself, but you want to do a hex dump from the atmega2560 to your computer. The other pololu links are for a firmware update to support the 2560's larger memory footprint.




    Here's the pinout for the ICSP header, https://dl.dropboxusercontent.com/u/14121640/CX20%20FC%202560%20ISP...

  • Mister T,

    Sorry, I never got the original firmware. I might just swap the AP to an APM 2.6. I don't know if you can retrieve the fw out of the Nova. Connecting with the Atmega directly and read content directly could be a solution if it is not protected. 

  • Hello Pal,

    Did you end up finding the original stock firmware? This evening I also made the mistake of upgrading to AC 3.1.5 and have lost my telemetry and the ability to tilt my Quanum Q2D gimbal. A friend of mine has an unmodified Hobbyking Nova. I wonder if it is possible to upload the original firmware from his Copter so I can post it and help others in our position.

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