This is a pin map for the Arduino Mega 2560 Rev3. All used ports are

RAMPS 1.4 - RepRap

Arduino Mega 2560 Rev3 Pinout, Atmega2560 Pin Mapping, EAGLE Files, Schematics, and More! - element14 Community

Uses the same ATmega16U2 USB as the original Arduino Mega 2560 R3.

Mega 2560 R3 with ATmega16U2 USB

Arduino Mega 2560 Rev3 — Arduino Online Shop

Discontinued - you can grab Adafruit Grand Central M4 Express featuring the SAMD51 instead!

Arduino Mega 2560 R3 (Atmega2560 - assembled)

Inland Mega 2560 MainBoard Arduino Compatible; 16MHz Clock Rate; 256KB Flash Memory; 8KB SDRAM - Micro Center

Keyestudio MEGA 2560 R3 Development Board For Arduino + 1Pcs USB cable+Manual

Arduino Mega 2560 Rev3 - AndyMark, Inc

Arduino Mega2560 R3 pinouts photo - Microcontrollers - Arduino Forum

Arduino Mega 2560 - R3

Arduino Mega 2560 Pinout, Projects & Spec