What bootloader is present by default on Arduino Uno?

Question

Or where can I find information about the default bootloaders present on each Arduino board? All I could look up was it could be one of these bootloaders on the ATmega chip:

• ATmega
• ATmega8
• bt
• Caterina
• Caterina-Arduino_Robot
• Caterina-LilyPadUSB
• gemma
• lilypad
• Optiboot
• stk500v2

This was the list present in the folder ~\Arduino\hardware\arduino\avr\bootloaders.

Answer 1

It is defined in the file "boards.txt" (arduino-1.8.7\hardware\arduino\avr\boards.txt).

For example, the Arduino Uno is called "Arduino/Genuino Uno", and it has the bootloader: uno.bootloader.file=optiboot/optiboot_atmega328.hex

You can find that .hex file in the folder arduino-1.8.7\hardware\arduino\avr\bootloaders\optiboot.

The official Arduino boards are shipped with the newest bootloaders. \ Sometimes the bootloaders are improved or changed. That is mentioned in the Release Notes. \ For example, the latest change to a bootloader is that the Arduino Nano now has the same Optiboot bootloader as the Arduino Uno.

When buying an Arduino clone board, anything is possible.

Some companies make their own Arduino-compatible boards with their own bootloaders.

• Battu007: Exactly what I was looking for. Thanks :)

Answer 2

Optiboot Bootloader for Arduino and Atmel AVR

https://github.com/Optiboot/optiboot/wiki

Take a look at this information.