Frequently asked questions are about powering an APM2.5 or why the same does not work or why it has failed.

Here is a simplified schematic showing the major components of the 5V/Vcc circuit on the APM2.5

Target Audience: Readers who do not have Eagle or are confused about using it.

You Need: Basic electronic schematic reading ability

Note that I have separated the PWM Output section into the upper left corner with a heavy purple line that is bridged by the jumper JP1 on the APM2.5. This is to emphasize that diode D1 passes current through JP1 (and drops voltage). The remaining energy is then called 'Vcc'.  Everything outside the purple corner is Vcc.

This is why the USB will power the APM2.5 when connected to a computer/USB hub. Note the fuse on the APM2.5 side of the USB connector AND another fuse on the output of D1. Another change from APM2.0 is the D4 6.0V Zener diode. If an over voltage is applied to the board, D4 will crowbar what it can to protect devices.

As with APM2.0, any 5V source connected to any of the indicated Vcc/5V points outside the purple corner (with GND of course) will power the APM2.5.

Also of note is the 'Mystery Port'. This port takes 5VDC before D1 and the fuse and is called 'JP_VCC'. Other clues to the mystery are the lines to 'ADC 12' and 'ADC 13'. A mystery indeed!

Any errors in this drawing from editing are mine.

I hope this can be used as reference for solving problems.



27-FEB-2014 Eagle files are now located HERE


Tags: (UAV)-autopilot-hardware, APM2.5

Views: 40807


Reply to This

Replies to This Discussion


I have about 20years experience looking at CAD and multilayer PCBs.

Not sure why you feel that 2.5 is the same as 2.6?

Look at the 2.6 board.

Above U3 the 3.3v regulator (APM2.5)

U$15 Has changed chip??

2.5 chip is not as big as the 2.6 chip??

Next to U3 the capacitors and chip components are all in a line on the 2.6 not on the 2.5

I don't have the Eagle files for 2.6 but the tracks seem to be different?

IC2 has moved right by about 0.1 inch.

The arrow for FRONT is in a different location.

Biggest change is that I cannot find some of the surface tracks.

The MP6000  - U5 has moved relative to U$12

U$14 has rotated 90degrees

The board has been re routed.

I can sort of understand if the designer does not want copies coming from other suppliers.

However, I am trying to fix mine!


Maybe mine is a copy!!!!

But I got it from UnmannedTech?

All the best,



The 2.5.2 and the 2.6 are the same. ( on the 2.6, there is no placement of the mag)
Have a look at the picture on Randy's blog above, you will notice they are both 2.5's the sot23-5 outline reg is the 2.5v2

Is the one you are looking at a 3DR one? And when did you get it?

Sorry, saw that, Unmannedtech.
So you need to ask for the 2.5 drawings, but need to specify, Not the 2.5.2 or 2.6.

Ok Philip,

So it is just called 2.6 because it has no mag chip?

The board is really a 2.5 not 2.5.2 (for which I have the Eagle files)

Confusing eh?

Big chages in the board from 2.5 to 2.5.2.

Thanks for this really critical clarification.

All the best,


>>>So it is just called 2.6 because it has no mag chip?

Correct.  The whole assembly is called a 2.6, but the board is just a 2.5 w/o the mag stuffed.

Ok, next question.  Where can find the Eagle files for 2.5 (not 2.5.2).


John, I've got zip of 2.5 from 2012.

Let's be friends so we can exchange pleasantries and email address. I can then attach the zip and email it to you.


Hey guys, I'm looking to build an APM 2.6 with a small modification. Anyone have a Digikey BOM for the 2.5 or 2.6 by chance? 

Is this just for you? Or are you making lots of them? What modifications are you planning? Some info would be great! You can pull the BOM off the Eagle files. It's not too hard to list it out for Digikey. Though for just a few boards it will be quite expensive.

Just remember to post your changes back here.
Reminds me of the time someone built a VW beetle completely from the Parts Department. He had a new beetle with a Cadillac price tag! A better approach would be getting a $20 atmega2560 and going from there with the sensors. Good luck.



Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Drone Delivery Challenge, is here

© 2014   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service