I've been testing my purple board through the USB and it works good enough to replace an ArduPilot Mega 1 on an EasyStar.  Everything is connected and the power jumper is in so the ESC is supplying system power.

But, the APM2 will not start up on either ESC or UBEC power.  Even wired in, it still boots on the USB power, as it has always done.  The APM1 never had any problems with power on this plane and another APM1 always works on a T-28.

Has anyone seen this problem with ESC/UBEC power? 

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I believe this has been found and solved.  When using APM2, it will not start if there is any traffic on the telemetry channel.  I had Mission Planner open and waiting for the startup info while applying power to APM2.  This method consistently prevented APM2 from booting.  I changed the procedure to have Mission Planner disconnected and the APM2 now boots normally when power is applied.

That's quite an edge case--it never occurred to us that anyone would try to boot up with Xbees already connected! But I have verified that what you describe does happen. I'll post this as an issue and we'll fix. 

According the dev team, this is a known issue with the Arduino Optiboot bootloader. It's really is an usual use case and easy to get around, as you say, so it's not a high priority for us to address. But perhaps worth reporting to the Arduino team. 

Since your team is actually the "developer" and knows the internal details, I will defer to you to make any report to Arduino. 

In the meantime, I feel this is reproducible enough that it should be in the Setup/APM2/First-Time Setup section and again in the Flying/Starting Up pages in the Repository.  I'll create an Enhancement Request for this issue.

It turns out that this is the way the Arduino bootloader is supposed to work. It registers any serial activity immediately after a reset as an request to load new firmware. It applies to all 2560 boards, so not only 5,000+ APMs, but also any other Arduino-Mega based board out there, of which there are hundreds of thousands. 

I think you're the first person to ever try the particular set of circumstances necessary to trigger it! 

Try this sequence out with an APM1, ie, apply power with Mission Planner connected and waiting on the telemetry link.  APM1 never acted this way even with the latest Planner version.  That's why it looked to me like a difference between USB reset and battery reset.

I'm still suggesting that this should be noted in the ArduPlane instruction pages.

If you're using a 1280 APM 1 it has a different bootloader. Optiboot only kicked in with the 2560 chips.

These are all 2560 (recent) APMs.

Yes, but on APM1 the telem port is on Port 3. On APM 2 it's shared with the USB on Port 1 via a serial multiplexer. 

I just received my APM2. I connected the jumper to power through the output rail. Once configured I was able to fly quadcopter a little. But for some reason the board stopped being able to be powered by the ESCs. The output rail has 5v when the battery is connected and jumper has continuity. Is there workaround besides adding an extra battery for APM2?

Hi Chris,

Actually I have the same issue. The APM2 does seem to have some problems booting up. I have a Xbee connected (Remote is powered off) and it still does happen. It boots and just the blue GPS light  on the main-board stays on solid (as well as the green power light and the blue GPS light blinking on the daughter board.

Two solutions:

1) Pressing reset starts the APM properly which indicates that it might not just be a bootloader issue.

2) Unplugging, replugging power many times... Eventualy it boots up.

Never happened with mit my APM 1 2560 in the same hardware config.

Let me know if there is anything in particular you would want me to test/verify. The issue is quite reproducible.


Same Issue for me too.

Only blue led will power on and stay solid.

To boot the APM2 I've to press the reset switch or power it by USB cable.


I've no xbee connected, only APM2 and 5V on output rail.

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