Boot problem fix for M4 V2

[JussiH]

The AQ team has identified a boot problem with the M4 V2 hardware and worked out a fix for it.

Boards that was shipped before Dec 22nd 2014 can be affected by this problem. It only happens on some boards.

In some cases boards will not boot properly or have problems with booting in bootloader mode under a USB only supply. In most cases the boards will boot normally with a battery connected, but a few users has been reporting problems with that too.

The cause has been identified to be R26 and the Fix is to remove it. There is no adverse effects to doing this, so it can be done safely on any board.

R26.jpg (164.85 KiB) Viewed 12000 times

It is not very hard to remove with a soldering iron, using the technique outlined in this video:



Anyone not comfortable with doing this can send a email to Viacopter to arrange sending it back to be fixed under warranty. But pls post problems here, maybe we can find a solution closer to your neighbourhood.

[Patnet]

R26 is already removed. When entering bootloader by holding the Bootloader button and switching on by touching the on/off switch, I only get a solid red, not the yellow and blue LEDs solid. I'm using a 1S lipo. Please advise.

[Max]

Just hold the boot button and plug in USB. You should get one solid red LED in the corner, other corner lights will be off. You're now in bootloader mode. You do not need to press the on/off button. With R26 removed you also do not need a battery attached (though it should work that way also).

-Max

[Patnet]

Thanks for you help, would you happen to know how to get a bootloader serial port? In QGC when I go to Communicate by Add Llink when in Bootloader mode, QGC won't pull a Serial Port. However, it does find one in non-bootloader.
I have STM32 Bootloader showing up in the Windows 7 Device Manager and have re-installed it using Zadig per the wiki.

[LPR]

Pat

The good news is that you don't need to have a bootloader port when flashing using a USB connection. You just chose the firmware you want and click on "Flash Firmware".

Larry

[Patnet]

Thanks so much.