Let's take an in-depth look at each part of the Arduino Uno's PCB to get a better understanding of how the Arduino works at the hardware level.
An In-Depth Look at the Arduino Uno PCB - Circuit Basics
How to Turn Arduino Prototype into PCB Production
Arduino Uno is a microcontroller board based on the ATmega328P (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM
Arduino Uno Rev3
Arduino Uno Specification – TOMSON ELECTRONICS
Arduino UNO Pinout Complete Guide [With Diagram]
Made an AT Tiny programming shield for an UNO. SLA printed the resist onto some copper clad then acid etched the board. : r/arduino
Arduino UNO - JavaTpoint
Make: Arduino Projects, How-Tos and More
What Is Arduino? – Simply Explained
PCB Basics - SparkFun Learn
Rugged CircuitsRugged Circuits Home of the Ruggeduino and Rugged MEGA