Inspired by an example question before beta, can I make the Leonardo bootloader take less that 8 seconds to run? It is very slow and I want to speed it up somehow.

  • 1
    Can you give us more details about your development environment (IDE you use). Did you burn the bootloader yourself, or did the board came with the bootloader already loaded? Do you have a link to the bootloader code on the net? Also, do you know if this delay is normal of all Leonardo boards? Because 8s seems to be an awful lot of time for a dev board to boot.
    – Ricardo
    May 6, 2014 at 13:36
  • It's the default IDE (this wouldn't make any difference, but OK), and i used the stock bootloader that came with the board.
    – TheDoctor
    May 6, 2014 at 13:57
  • What version of the official Arduino IDE? I'm trying to determine the exact bootloader code base. But it won't be helpful because the bootloader you're using didn't come from your IDE. Since it came installed from factory, we may never know which one it is. The only hope is for you to burn the bootloader from your IDE into the board and report the same delay. If you decide to do it, just beware of what you're doing.
    – Ricardo
    May 6, 2014 at 14:00
  • Or someone may give it a try and post an answer assuming one given version of a given bootloader out there. It's possible, but not optimal.
    – Ricardo
    May 6, 2014 at 14:03
  • 2
    Yes, you can shorten the value of TIMEOUT_PERIOD in caterina.c - see leonardomiliani.com/2013/… But beware that a shorter value may make it harder to recover if you load a sketch that breaks the USB support. May 8, 2014 at 16:24

1 Answer 1


Detailed instructions on how to shorten the bootloader time of Leonardo etc. are explained [here] (as stated by @Chris Stratton).

The crux of the matter was to redefine the timeout period

/* ./arduino/hardware/arduino/bootloaders/caterina/Caterina.c */
#define TIMEOUT_PERIOD 8000

to a lower value.

However I do not have such issues with Leonardo it boots very fast. So this issue depends on your environment.

There is also OptiBoot, an alternative bootloader that really boots faster link:

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.