Cannot connect to APM2 - No RX light? *solved*

Hello,

I am helping a friend setup his quadcopter with APM2. We have updated it to 2.7.1. We calibrated ESCs, we configured the Transmitter. It flew okay with unbalanced props. We flew it this one time.

We took the frame apart to move his ESCs inside the frame. After doing this it would not fly correctly. Throttle would jump from idle to over 50% somehow. As a result it hit the ground (perfectly flat on the landing gear) a little hard and he broke two props by hitting the legs on my BBQ.

We assumed ESC or Transmitter calibration needed to be redone. We redid the ESC calibration.

When we went to redo the Transmitter configuration the APM disconnected from Mission Planner during the configuration. WTH, eh? The Connect button in Mission Planner didn't reconnect it.

We reopened Mission Planner and tried again. Connect button still did nothing.

Disconnected APM from USB and reconnected. Then the Connect button worked. After just a few seconds, the APM again disconnected form Mission Planner. Connect would not work again until another unplug then replug into USB. However, the next time we got "USB device not recognized".

Unplug, plug in..."USB device not recognized". Unplug, plug in..."USB device not recognized".

Unplug, plug in.... Installed correctly (in Windows Device Manager), but Mission Planner won't connect.

Unplug, plug in....  Installed correctly (in Windows Device Manager), Mission Planner tries to connect but times out.

Each time we unplug it and plug it in again we get one of these three results. I have recorded several videos of this issue. Please check them out.

http://www.youtube.com/watch?v=ClA7FffSrdA

We never get a flash of the Rx light on the APM any more.

We tried another USB cable and that did not help. Tried another USB port. There is no USB hub...

Another AMP2 (mine) connects perfectly. This shows that it has to be an issue with my friend's APM2.

If I connect to my working APM2 i see mostly Tx light and the odd very short Rx light blink. Likely a command or request from Mission Planner.

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Permalink Reply by Derek Ernewein on August 11, 2012 at 7:13pm

Not that it matters, but Mission Planners I am using is v1.2.4 mav 1.0.

We also tried the Reset button on the board. It made no difference. I suspect a hardware issue.


DistributorPermalink Reply by Dany Thivierge on August 12, 2012 at 11:26am

One thing that I've seen when USB connection and MP does that is that I reboot the computer and it goes fine again! :) 

Strange but somehow super Windows gets confused.  happen for me often as I test several boards when assembling them but I dont know what is causing it... Once it starts doing that no APM boards would work fine until I reboot the computer... 

Try that first as I see your APM healthy (red/blue seems happy) 

Also if you see no red/blue led try to let the APM powered on for like 2-3 minutes without connecting it... it may be doing things like formatting the memory card... after a short while it will start blinking happily again. 

Permalink Reply by Derek Ernewein on August 12, 2012 at 2:24pm

Hey Dany,

We did reboot the computer. I have seen that issue before too. If that was the issue this time though then the other APM would not have worked.

I also uninstalled and reinstalled the Windows driver.

I also left the APM unplugged for over and hour and came back to it thinking it could be some one time issue that would go away as components discharged... That theory/test also didn't help.

I will try another computer right now, but I have zero faith in that doing anything as the other APM works fine of this computer.

I'll also test plugging the APM in powered but not connected for 30 minutes and see if that does anything.

Permalink Reply by Derek Ernewein on August 12, 2012 at 3:30pm

I left it plugged in for over 30 minutes. Then I unplugged the USB and plugged it back in.

It appears to be working! Connects to Mission Planner.

I suspect that you were right, it needed time to complete something. At least I suspect that was the last issue that it just worked through. I assume that work was a reset because I hit the Reset button on the board a while ago.

But the issue before that must have been something else. I suspect that we had a power loss due to the USB cord coming loose or something when doing the transmitter configuration. Perhaps the incomplete configuration caused the APM to not boot correctly. Just a thought...


DistributorPermalink Reply by Dany Thivierge on August 12, 2012 at 6:42pm

I've seen faulty USB cord doing a lot of bad things to APMs... We spent several hours on a particular customer setup, debugging and troubleshooting a lot of things... resoldering, cleaning the board... every times it was something different always leading to total corruption of the APM... And one day he contacted me telling me that is was "just" a faulty cable! 

These little buggers of APMs are really sensitive on the bootloader... something to improve in the future, maybe on USB connect we should introduce a delay to do nothing for 10 seconds? (but then again some people might just connect it and expect them to work right away...) 

So Derek, keep a good eye on that APM, to extensive testing with it before going on a long ride.

Let me know

Dany

Permalink Reply by Drone Savant on August 18, 2012 at 12:00am

Thanks for posting this video. I've been pulling my hair out tonight trying to figure out why one of my boards randomly stopped working. I had a spare APM2 on the shelf from Dany @CanadaDrones that I had never used. When I did the swap it too caused my ESC's to beep, and it would not boot to the point of flashing the A-B-C less for a gyro init. IF it would connect in Mission Planner it was usually so momentary I could not even catch a single parameter over MAVLlink. 

You've given me some hope! Hearing you say that it had to sit for 30 minutes makes me think the SD card / data-flash we being formatted. http://code.google.com/p/arducopter/wiki/AC2_Troubleshooting#My_APM... seems to hit that same point right on the head: "My APM 2 is locking up - The cause is probably that the dataflash card not initializing correctly".

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