APM2 does not connect to USB

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What steps will reproduce the problem?
1.it was working ok, on COM4
2.after a normal flight, does not connect to computer anymore. not using 
xbee/3dradio or any telemetry.

What is the expected output? What do you see instead?
when connecting to computer, it lights the leds and get GPS 3dfix, but doesn't 
open the COM port.

What version of the product are you using? On what operating system?
APM2, windows 7 64bits. worked ok for about 2 months.

Please provide any additional information below.
on the day it stopped working, i accidentally inverted aileron servo and 
airspeed sensor (connected airspeed on servo output and servo on airspeed 
input), but after this connection was still working.

Original issue reported on code.google.com by ze.may...@gmail.com on 10 May 2012 at 10:24

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does it appear in windows device manager any more?

Original comment by Meee...@gmail.com on 11 May 2012 at 5:13

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no, now it doesn't appear on device manager anymore. it powers from USB, but no 
notifications from windows appear. i also tried to connect with another cable 
and another computer, and still no connection.

Original comment by ze.may...@gmail.com on 11 May 2012 at 3:59

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by the way, i have a Prolific USB to TTL converter from Remzibi OSD. may i 
connect APM2 by  this device? if yes, i´ll need to connect Tx to Rx, Rx to Tx, 
gnd to gnd as remzibi. i believe than it´s better to power the apm by receiver 
5V rail, as in remzibi. right?

Original comment by ze.may...@gmail.com on 11 May 2012 at 4:38

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on apm2 the usb serial interface also controls the ppm encode. so that wont 
work. you might have to look at the wiki about uploading the ppm encoder 
firmware again using dfu

Original comment by Meee...@gmail.com on 12 May 2012 at 11:42

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oh crap...can you send a link to any step-by-step turorial? i made a quick 
search for "dfu" on the wiki, and found nothing that i seem to understand.

also, is there any hint for why did it happened?

Original comment by ze.may...@gmail.com on 13 May 2012 at 10:05

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i talked directly to 3DR, and here's a good tutorial they sent me:

http://code.google.com/p/arducopter/wiki/APM2Encoder

the only problem is that my APM2 does not disconect/reconect to usb when 
rebooting, and then cannot connect with flip. i still don't know what's wrong, 
and what can i do.

Original comment by ze.may...@gmail.com on 16 May 2012 at 11:32

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tryed the DFU, no luck. also tried ISP for reprogramming 32u2. programming was 
ok, but still no connection.

sent e-mail to 3dr help again saturday, i'm still waiting for an answer, but 
i'm quite sure i'll have to send it back for the factory.

Original comment by ze.may...@gmail.com on 24 May 2012 at 2:56

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ze.mayer0, I will mark this as "Done" as it appears to be a hardware problem. 
Re-open it if you suspect otherwise, please

Original comment by andreas@antonopoulos.com on 5 Jun 2012 at 5:51

• Changed state: Done

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This just happened to me for the 2nd time.  

1st time: Was attaching airspeed sensor.  Board had never been in the air.  
Xbee & USB worked great 10 minutes prior.  After installing airspeed sensor, 
couldn't connect via USB (or xb) any longer.  Still visible in windows.  
Mission planner just coudln't connect.  In fact, every time I attempted to 
connect, the board would reset: It'd go through the calibration lights & twitch 
the servos.

Tonight, the same thing happened.  This time I was trying to connect my xbees 
to the replacement board 3DR sent on Thursday.  I had been interacting with the 
board in stabilize 5 minutes prior.  Powered down, connected xbee (in same 
config as with previous board) and nothing.  Xb never connected, and USB no 
longer available.  Board resets when I try to connect to it via the Mission 
Planner.

Frustration is beyond measure this evening.

Original comment by hagfe...@gmail.com on 11 Jun 2012 at 4:37