Amazon.com: Geekstory for ATMEL 51 AVR USB ISP ASP Microcontroller Programmer Downloader with Cable + 10Pin to 6Pin Adapter Board for Ender 3 or Ender 3 Pro : Electronics
Kanda - Guide to AVR ISP Circuit Schematics
Introduction to Atmega16 - The Engineering Projects
Introduction to ATmega328 - The Engineering Projects
Tiny AVR Programmer Hookup Guide - SparkFun Learn
Digital Input/Output Ports on AVR - Developer Help
ATMega328P Microcontroller Pinout, Pin Configuration, Features & Datasheet