[Frank1001]

Installed CC3D Atom in a fixed wing.
Everything works fine. When I disconnect the USB everything keeps working until I cut the main power.
When I put the main power back on without connecting the USB nothing works.
The USB port has not to be connected to the computer, a simple USB charger is enough to make everything work fine.
It seems that the CC3D Atom also needs power through the USB port.

Is there a problem with the CC3D Atom or what am I doing wrong?

[TheOtherCliff]

Another user was saying the same thing a few weeks ago.  I don't recall seeing a fix.  Search the forum...

Is this current 16.09 LibrePilot or something else like OpenPilot?  And your GCS and firmware versions must match.

Is that a smart charger (talks to the device like some cellphones require) or a stupid simple power supply (unauthorized charger will display on some cellphones).

What does your Hardware page look like?  Do you have an OSD (that acts like a telemetry stream, like USB)?  Have you used the virtual Comport stuff or other strange stuff on the Hardware page?

Nothing works...  Have you tried to arm and throttle it or just looked at an OSD or GCS?

[Frank1001]

Thanks for the reply.
I'm using the latest version (16.09) of LibrePilot on a MAC
As far as I can see the hardwarepage shows no abnormalities. No abnormal virtual com.
GCS looks fine when I arm en throttle it, but I can only see GCS with an USB connection... No way to see it with without the USB connection, I have no OSD.
It does not matter whether the USB is connected to my laptop, a phone charger, the charger of my Ipad.
I think it just needs the 5v on the USB port

[TheOtherCliff]

Are you sure your ESC puts out 5 volts on the black (/brown) and red wires?  Can you measure the voltage it puts out while connected to the CC3D?  What you describe would happen if the ESC did not have a BEC in it.  Some are made that way.

If the ESC/BEC puts out 5V even when connected to the CC3D, then the CC3D may have a problem.  I recall that a few months ago a user had a similar problem.  I am pretty sure he finally just wired 5V power into the USB port and flies it that way.  I would guess that you could splice together a USB cable and a servo cable to take power from an unused ESC (/servo) connector and put in into the USB port.  Only do this if you are comfortable with tracing the connections with an ohm meter.

This would be a very specific hardware problem.  There is a pair of diodes that allows current to flow into the circuit from either the USB or the ESC bus.  If the ESC bus diode was fried it would do exactly what you describe.