Programming the Arduino Uno bootloader

[kaycebasques]

optiboot

use the legacy arduino ide 1.8.19

assume it's at ~/arduino/arduino-1.8.19

this info seems fine or at least not completely outdated:

• https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP
• https://www.electronicwings.com/arduino/basics-to-developing-bootloader-for-arduino

Programmer

• File > Examples > ArduinoISP > ArduinoISP

Tools > Board > Arduino Uno

Tools > Port > /dev/ttyACM0 (Arduino Uno)

Tools > Programmer > ArduinoISP

Upload

Bootloader

put the AVR tools in your path:

export PATH="$PATH":"$HOME/arduino/arduino-1.8.19/hardware/tools/avr/bin"

get the latest optiboot code: https://github.com/Optiboot/optiboot

build latest optiboot code:

make ENV=arduino LED_START_FLASHES=2 atmega328

Copy that optiboot_atmega328.hex file over to
~/arduino/arduino-1.8.19/hardware/arduino/avr/bootloaders/optiboot/optiboot_atmega328.hex

Arduino expects this path and filename. Can't change it.

"old style wiring" mentioned on arduino.cc page was fine

Tools > Arduino as ISP

Tools > Burn Bootloader

Try also LED_START_ON=1 to verify that things are
changing

It's the orange LED labeled L (somewhat close to TX and RX
LEDs)