#include <TimerOne.h>

static int ledou[] = {4, 5, 6};
void setup() {
  for (int i = 0; i < 3; i++) {
    pinMode(ledou[i], OUTPUT);
  }
  Timer1.initialize(1000000);
  Timer1.attachInterrupt(schaltung);
}

void loop() {

}

void schaltung() {
  for (int r = 0; r < 3; r++) {
    unsigned long zeit = millis();
    if (millis() - zeit < 5000) {
      digitalWrite(ledou[r], HIGH);
    }
  }
}