Arduino Nano: PPT VOX

/*
  Rig PTT VOX
  Detect D4 dari Audio
  Output D3 ke Switch

  modified 2021 Dec 3
  by Onno W. Purbo
 */

boolean State=LOW;
boolean inPin=4;
boolean outPin=3; 

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin 3 as an output.
  pinMode(outPin, OUTPUT);
  pinMode(inPin, INPUT);
}

// the loop function runs over and over again forever
void loop() {
  State=digitalRead(inPin);
  digitalWrite(outPin, !State);
  delay(10);
}

Alternatif Lain

/*
  Rig PTT VOX
  Detect D4 dari Audio
  Output D3 ke Switch

  modified 2021 Dec 3
  by Onno W. Purbo
 */

int State=LOW;
int inPin=4;
int outPin=3; 

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin 3 as an output.
  pinMode(outPin, OUTPUT);
  pinMode(inPin, INPUT);
}

// the loop function runs over and over again forever
void loop() {
  State=digitalRead(inPin);
  if( State==1 )
     digitalWrite(outPin, LOW );
  else
     digitalWrite(outPin, HIGH );
  delay(10);
}