Hacking
Legacy documentation that focuses on extending the Arduino hardware and software, mainly for classic AVR-based boards such as the UNO and Mega.
Software
The bootloader is a small piece of software that allows uploading of sketches onto the Arduino board. It comes preprogrammed on the microcontrollers on Arduino boards.
Upgrading the firmware of the Atmega8U2 chip on an Uno or Mega2560. This chip acts as the usb-to-serial converter and can be updated via USB.
The Firmata library implements the Firmata protocol for communicating with software on the host computer.
Libraries are files which provide your sketches with extra functionality.
This tutorial shows how to play MIDI notes from an Arduino programmed to appear as a general MIDI device.
The bootloader is a small piece of software that allows uploading of sketches onto the Arduino board. This document explains how to bootload an Arduino Mini
Learn how to control pins on an Arduino through three different registers (DDR, PORT, PIN).
The Arduino preferences file contains many options for customizing the way Arduino compiles and upload sketches.
How to use the Arduino software with a hardware programmer (eliminating the need for the bootloader and saving program space on the chip).
Learn how to upgrade the firmware for your Arduino WiFi Shield.
Hardware
The pinout for the ATmega328P, the microcontroller used for Arduino UNO.
A diagram showing the correspondence between the pins on an Arduino board and those of the ATmega168 microcontroller.
This page will show you how to upgrade your Arduino NG to auto-reset when powered or uploaded to.
Instructions for making a cheap piece of hardware that lets you burn the bootloader to an Arduino board or upload sketches to a board with no bootloader.
A diagram showing the correspondence between the pins on an Arduino board and those of the ATmega8 microcontroller.
a diagram showing the correspondence between the pins on an Arduino board and those of the ATmega168/328P microcontroller.
A diagram showing the correspondence between the pins on an Arduino board and those of the ATmega2560 microcontroller.
A diagram showing the correspondence between the pins on an Arduino board and those of the ATmega32U4 microcontroller.
a diagram showing the correspondence between the pins on an Arduino board and those of the SAM3X microcontroller.
Instructions for replicating the circuit of an Arduino board on a breadboard.
This tutorial shows you how to build an Arduino compatible breadboard with an Atmel Atmega8/168/328 AVR microcontroller and FTDI FT232 breakout board from SparkFun.