How to Insert 'print float support' text in Arduino 1.8.5

Hi, I'm trying to edit Prusa MK3S printer code (, but to do so I need to be able to enable 'print float supprt' in the Arduino platform.txt file.

Arduino 1.6.9 platform.txt contained a line: "compiler.c.elf.flags=-Wl,--gc-sections", to which was added "-Wl,-u,vfprintf -lprintf_flt -lm" thus enabling 'print float support'.

Arduino 1.8.5 platform.txt compiler.c.elf line reads: "compiler.c.elf.flags={compiler.warning_flags} -Os -g -flto -fuse-linker-plugin -Wl,--gc-sections".

Does anyone know how to enable 'print float support' in Arduino 1.8.5? I've contacted Prusa's support forums, so far no help, and their build instructions are outdated.

Fair farren

Did you try adding the same flags? If so, did it work? If not, why not?

No, I didn't add any flags, because I don't know what flags are or how to add them, or what to add them to...

YoungR0se: because I don't know what flags are

"Flags" is another term for are options passed to a program via the command line. You already know what the flags are that need to be added:

YoungR0se: to which was added "-Wl,-u,vfprintf -lprintf_flt -lm"

Those are flags.

YoungR0se: or how to add them

  • Open the file in a text editor.
  • Paste the flags into the file in the correct place.
  • Save the file.

YoungR0se: what to add them to...

Add them to the line in platform.txt that starts with compiler.c.elf.flags=.