/*
  Read pwmIn on pin 4 (100 Hz, 10 ms period) and replicate on pin 3 (pwmOut)

  Using delayMicroseconds(1000); // 1 ms
  Up to 10 % jitter on pwmOut as expected due to blocking delay. 
  pwmIn 100.00 Hz (Wokwi Logic Analyzer)

  Using delay(1); // 1 ms
  Up to 10 % jitter on pwmOut as expected due to blocking delay. 
  pwmIn 100.00 Hz (Wokwi Logic Analyzer)

*/

const uint8_t pwmIn = 4;
const uint8_t pwmOut = 3;

void setup() {
  pinMode(pwmIn, INPUT);
  pinMode(pwmOut, OUTPUT);
}

void loop() {
  digitalWrite(pwmOut, digitalRead(pwmIn));
  //delayMicroseconds(1000);
  delay(1);
}