const byte ledPin = 12;
const int ledON = 200, ledOFF = 1000; // LED state intervals
unsigned long timer;

void setup() {
  pinMode (ledPin, OUTPUT);
}

void loop() {
  if (millis() - timer >= (digitalRead(ledPin) == 0 ? ledOFF : ledON)) { // read pin state, set interval
    timer = millis(); // set new timer for next interval
    digitalWrite(ledPin, !digitalRead(ledPin)); // set LED pin state to opposite (!) current pin state
  }
}