Pro Micro pinout

The Arduino Pro Micro is cheap (~3$) and perfect for small boards (less than 81 keys). With a little hack though, it can drive a keyboard with up to 100 keys.

Arduino Pro Micro - ePro Labs WiKi

Pro Micro ATMEGA32U4 Arduino Pins and 5V, 3.3V Explained - Robojax

STeMCell - STM32 based pro micro pinout : r/ErgoMechKeyboards

OSOYOO 1x Pro Micro Board ATmega32U4 Leonardo 5V/16MHz Module Board Type C Port for Arduino : Electronics

Arduino Pro Micro Pinout: Connection Pins for the ATmega32U4-Based Microcontroller

Pro Micro RP2040 Hookup Guide - SparkFun Learn

flashtree 4pcs Pro Micro Atmega32U4 5V 16MHz Bootloadered IDE Micro US

Fixing an Arduino Pro Micro: the USB Port Came Off !! : 17 Steps - Instructables

Pro Micro & Fio v3 Hookup Guide by SparkFun Electronics Datasheet