The Full Arduino Uno Pinout Guide [including diagram]
Interfacing Arduino To A Touch Sensor - Makerguides.com
Arduino - Arduino Uno (R3) - ShareTechnote
How can the VCC pin (AKA "3.3V") be dual functioning as a regulated 3.3V output AND a secondary power input for the RTC module?
Is it okay to connect 5v pins from Arduino to an 'Rx' pin of ESP8266 without using a logic-level converter? The VCC is connected to 3.3v, though. - Quora
Introduction to Arduino Uno - The Engineering Projects
Installing a Bootloader on the MicroView - SparkFun Learn
SHORT USING Vcc LINE FOR BOTH HX711 AT 80Hz AND VOLTAGE SUPPLY - Project Guidance - Arduino Forum