Here are diagrams that show the pinout of the micro controller Arduino Atmega and most basic circuit diagram with the crystal. Also a pinning and tqpf ATmega328 with Arduino bootloader code. Many times we lost to the passage of Arduino + breadboard to design on paper and then on the PCB . AT MEGA 328 Arduino pinout Circuit Diagram Arduino bootloader Port B has pins B0 to B5 Port C pins have C0 to C5 Port D has pins D0 to D7 Arduino AT MEGA328 Pinout TQFP