Caddx GM3 does not work with firmware > 3.4

ArduCopter Copter 4.6
1

My Caddx GM3 (actually it’s a XF C-20T which should be the same) works fine with firmware 3.4.
After upgrading to 3.6 it does not work at all.
The same happens with 3.8.

ArduCopter 4.6.2

2

Same here, but for Caddx GM2.

3

I think I am going to have to get one

4

Works perfectly with 4.6.2. I happened to fly with it this morning.

I followed the wiki: CADDX Gimbals — Plane documentation

As described in the wiki, I needed to update the gimbal firmware. The Caddx upgrade cable is not absolutely necessary; a normal UART-USB converter will also do the job.

Rolf

5

And which firmware version You have in Your gimbal?

6

I suspect it’s 3.4, but I can’t say for sure because I’m on the road right now. I would download the latest version (3.6).

Rolf

7

We have a issue for this, Caddx GM3 does not work with firmware > 3.4 · Issue #30958 · ArduPilot/ardupilot · GitHub

The working theory is that something changed on the changed on the Caddx side after firmware version 3.4 so our driver no longer works.

8

Sorry, I mixed up the ArduPilot firmware number with the gimbal firmware. Ouch. :frowning:

Rolf

9

I have been talking with caddx and this is what they have said so far, " Dear Customer

Thank you for your reply. Firstly, after numerous practical tests, we did not find the compatibility issue you described.

You can first confirm whether you have changed the channel to CH01 in the software after upgrading the firmware to V3.6, instead of leaving it blank.

Secondly, what is your control method, is it transmitted through PWM or UART protocol?"

Screenshot 2025-09-23 115225
Screenshot 2025-09-23 115225818×133 5.77 KB

1 Like
10

ArduPilot control is via the UART protocol.

11

Yes I am aware of it being controlled via uart. I am not home to test but they have said they have no issues using latest arducopter with the gm3 and 3.6 and they have changed “nothing” that would have broken compatibility from 3.4 to 3.6. Again that is caddx themselves saying that.

12

Did a quick test and indeed setting CH01 fixes this issue. I can again control gimbal over uart. But… only to first reboot after getting out of gimbal config tool. EDIT: Because I was too stupid and skip “Save params to flash” button. :slight_smile:

2 Likes
13

Awesome that what I was hoping for!

14

@406FPV,

Well done figuring out this issue! I’ll update the wiki

Thanks @Adam_Borowski for testing.

1 Like
15

All credit goes to caddx, they are really the ones!

16

I’ve created a new wiki PR which adds info about this new setting Common: Caddx input channel requirement added by rmackay9 · Pull Request #7133 · ArduPilot/ardupilot_wiki · GitHub

2 Likes
17

I have pushed a new PR that allows the gimbal lock mode to be changed. The default mode is HORIZ lock, which locks to the horizon, which is not very usable if you FPV via the gimbals camera…with an AUX switch you can now select either FPV (gimbal is locked to vehicle frame..ie just stabilized camera which can be yaw’d or tilted by RC) and PITCH_LOCK, which locks the tilt with respect to the horizon, but follows the vehicles roll which is sometimes preferred for more realistic stabilized video, as well as the current default of HORIZ_LOCK

here is the PR: Roll pitch ef mount lock aux sw option for CADDX mount by Hwurzburg · Pull Request #31461 · ArduPilot/ardupilot · GitHub

its been bench tested with CADDX 3.6 firmware, but should work with 3.4 or XFRobot 3.9…if someone needs a test firmware before it gets merged into master (aka “latest” on the firmware server) let me know and I will try to get some time to build it for you…but I expect it to be merged in a few days

1 Like