Forced to use flashlight mode to upload code

When launching my code from the IDE everything works fine, until my “dynamic memory used” exceeds 73%. After that I can only upload a new build by first putting my Arduboy into flashlight mode. Is this problem unique to me or is it a known issue? I can live with it, but it is a little annoying. Any advice on this?

Most likely you’re encountering the Arduino “magic number” problem. There isn’t much you can do about this for an Arduboy with the standard Leonardo bootloader. If this is the problem, replacing the bootloader with one of @Mr.Blinky’s Cathy bootloaders should fix it.


Unfortunately this is a bug that was inherited by using the Leonardo bootloader for the Arduboy. Before flashlight mode was built into the library, it bricked peoples units and was a huge problem in the early days.

And as noted, the new bootloader in the FX fixes this. I’d like to offer you a mod chip, as using that will upgrade and fix it but they are all sold out again… And it was supposed to be the last batch…


Any of the non-FX Cathy bootloaders should also fix it. You just need an In Circuit Serial Programmer (ICSP) to install one.