unsigned long onperiod = 1000;        // variable - set this to desired on time
unsigned long offperiod = 2000;       // variable - set this to desired off time
byte led = 2;                         // led connected to this pin

/* 

- I call this "millistime" because I use the variable "time1" often in my other code
- millistime1 can be assigned to a trigger

*/

byte ledstate = LOW;
unsigned long millistime1;
unsigned long millistime2;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("power on");
  pinMode(led,OUTPUT);
}

void loop() {
  millistime2 = millis() - millistime1;
  if(millistime2 == offperiod && ledstate == LOW){
    Serial.print("ON FOR:");
    Serial.print(onperiod);
    Serial.println(" MILLIS");
    millistime1 = millis();
    ledstate = HIGH;
    digitalWrite(led,HIGH);
  }
  if(millistime2 == onperiod && ledstate == HIGH){
    Serial.print("OFF FOR:");
    Serial.print(offperiod);
    Serial.println(" MILLIS");
    millistime1 = millis();
    ledstate = LOW;
    digitalWrite(led,LOW);
  }

}