James Bennet
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APM 2.0 - Unsolicited mode change when in Auto

Started this discussion. Last reply by James Bennet Feb 27, 2013. 2 Replies

Hello APM folks, I’m really stuck on this one and have searched the forums for ideas but I’m not getting very far. I’ve had my Bixler 2 flying well in Auto mode, generally it does a great job at…Continue

Tags: mode, change., Unsolicited, Change, Mode


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Please tell us a bit about your UAV interest
build my first "drone" when I was 14 with a chunky 35mm camera in a glider. Things have come a long way since then

Comment Wall (4 comments)

At 10:22am on August 2, 2012, Steven G said…

Hi James,

Re your radio. Basically, I suffered from a lot things that are not clearly published. I got mine working fine. Here is a list that might help you:

1. Triple check all your connections

2. Upload latest firmware

3. In MP, if you can "read" both radios, the radios ARE WORKING.

4. Make both radios settings are exactly the same

5. Make sure your port settings are set to the correct modem speed

6. While live, over the air, you can NOT be plugged into the computer on the air side, only the ground side. In other words, air has to be powered with battery like flight config.

Good luck. I am sure you will get through it


At 3:59pm on August 2, 2012, Steven G said…


All must be the same. ECC should be checked on both and OpResend. Make sure port settings match. Also, why 11 for power instead of 20?

It seems like your radios are working fine if you can get the read out above over air. Can you?

Hate to ask again but are you sure you have the APM2 to radio hooked up correct? Tx>Rx Rx>Tx? You should get bright flashing red on air and faint flashing on ground. You are connecting to right ports on ground and "hit connect button"?


At 4:49am on August 3, 2012, Steven G said…

Hi James,

Originally, I ended up with the no heartbeat when I hit connect. Yes the forums are full of helpful people, many with good advice and some not so good. I wish the Wiki was way more detailed with step by step and wiring block diagrams. Would have helped me a bunch at the beginning.

Back to you:

Yes the red LED on the air radio flashes immediately upon connection indicating the radio is sending data. It is bight red. It flashes continuously after the APM2 boots, as well.

Connect> For me and I don't think I am alone, you HAVE TO CONNECT to get telem. You would do this on the Flight Data screen only. Now, where the confusion comes in, on the Config screen, you don't hit connect, you just make sure you are on the right Com and hit Load.

I know you are a smart guy but so am I and I had fixed the radio and broke my fix by a misconnection. That's why I keep asking have you triple checked everything.

GPS lock is unimportant wrt radio telem.

Air on bat and hooked to right term block and polarity correct?

Com Ports on your computer set to same 57600? 8 0 1 on parity etc.

Are you sure you have the correct com port in the MP? You can check using Device Mgr and unplug your unit.

All that said, I do remember reading on the 433MHz radio forum, that there were some issues unique to that freq radio. You may want to check that out.

I wouldn't even bother with 3DR tech support, I have found it useless.

Good luck again. I know this can be maddening. For me, once I was sure the radios were working, I thought it would be unlikely that the APM2 was somehow dead.

The lack of a no Heartbeat msg may be a clue. When you hit connect, you should see a data load timer bar the same as when you connect to the APM2 through USB. The difference will be that it times out and says, no heartbeats detected.

Sorry to ramble,


At 10:47am on August 3, 2012, Steven G said…


I am glad you got it working! Once you know the radio is working, the rest is trouble shooting and taking nothing for granted.

Good luck with the rest of your project. Once you get all the bugs worked out this is awsome hardware and software.


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