The board that started Arduino's Nano family, the Nano is a classic platform ... Their onboard LEDs are connected to pin D13, and their serial RX/TX pins are on pins D0 and D1, respectively.

Nano Sensor Interface * Arduino Nano (v3) in Sleep Mode * T.K.Hareendran/2018 */ #include <avr/sleep.h> #include <avr/power.h> int tgrPin = 2; // Trigger Input_Interrupt 0 Pin int drvPin = 13; // ...

also compatible with Arduino Uno/Nano, that reads the voltage from the sound sensor module connected to A0 which is then displayed on the Arduino IDE’s Serial Monitor. Further, the D13 output goes ...