I'm constantly loading and testing code and the power setup of the 2560 can be a bit of a pain. Mainly, the radio does not receive power because the Servo rails are only powered via a Lipo, which can be very dangerous. I never do anything but fly with a Lipo connected and I certainly don't connect one indoors. I'm just paranoid that way.


This hack will power the radio half of the servo rail with 5V from the APM's USB connection. The idea is to spilt the 5V rail into two halves. If you use an X-Acto knife you can easily cut the trace connecting both sides. I cut the ground rail in half as well, then used some solder to repair the bridge. Then I connected the 5v from the APM to the input side as indicated below. Now I can power the radio with the USB.


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Comment by Jason Short on September 21, 2011 at 8:24pm

No it won't work exactly the same. I'm not entirely sure what mods would work for the 1280.


Comment by Jose Angel on September 21, 2011 at 10:19pm

In APM 1280 I remember that USB was enough to power my radio transmitter, so no nead to this hack!

The problem was that you cannot power at the same time from USB and a BEC ESC because you fry the board!

Comment by Sylvain on September 22, 2011 at 2:43am

One question.

does the receiver still poweres by the BEC when the LIPO is pluged with this mod?

Or does the BEC power the Board which power the receiver?

Comment by steve on September 22, 2011 at 5:41am

I'm using a 1280 on a quad with separate BEC and connect USB and LiPos at the same time. I've never burned the board doing it that way. I usually connect the LiPo power first and let it boot up (props off of course) and then plug in the USB. I have a 2560 also and am considering this mod. Were there changes in the way the rail is powered from the 1280 to 2560? Is there a list of overall changes?

Comment by Jose Angel on September 22, 2011 at 1:10pm

F11music, in the past I have blown one APM powering 1280 in that way, so please be careful and confirm that what you are doing is not dangerous for the board.

Comment by Olivier ADLER on September 23, 2011 at 12:57am


Another way is to connect Motors using the Lipo high power connectors, and use Lipo voltage connector to power the BEC.


So that when you want to test, just disconnect motor power, but keep the Lipo voltage connector powering the APM radio side.


I did one more modification : remove the USB fuse, because i never need to power the board through the USB connection. I've found that USB is more reliable like this (almost no more FTDI crashes).




Comment by Andre S on September 23, 2011 at 4:38am


I'm also very confused now. I remember in the times when there was only the 1280 it was said that it safe to power the APM from both USB and LiPo/ESC at the same time and even _required_ if one wants to avoid problems during code upload. Now it seems that with the 2560 things have changed? Since I'm planning to upgrade at some point it would be nice to know for sure.. Thanks!

Comment by Andre S on September 23, 2011 at 4:40am

..and yes, I'm powering APM 1280 from both USB and LiPo/ESC when doing upload, HIL simulation, etc., since that is the only way to keep the servos from jittering all the time even when there is no control input. So far it has worked fine for me. Could it be that there are differences between the boards or even the ESCs?

Comment by Jonathan Challinger on September 23, 2011 at 10:30pm

I power my APM and servos from a BEC (Western Robotics Hercules) connected to a 3s lipo's balance connector. Easy since I already have the balance connector going into the voltage divider.

On the bench, I have a 12v power supply (modded computer power supply with binding posts) and a banana plug to balance plug cable.

This way, I can also disconnect the ESC from the battery so that the motor cannot be powered without ever turning APM off. I'm also protected from ESC failure.

Comment by Glenn M on December 14, 2011 at 4:24pm

Is the cut in the photo at the top marked in the wrong place? Should it be between in0 and out7. The photo above has the cut between in0 and in1


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