/*--------------- by JediRick -----------------
  boolean        (8 bit)   -  [true/false]
  byte           (8 bit)   -  [0-255] unsigned number
  char           (8 bit)   -  [-128 to 127] signed number
  unsigned char  (8 bit)   -  [-128 to 127] signed number
  word           (16 bit)  -  [0-65535] unsigned number
  unsigned int   (16 bit)  -  [0-65535] unsigned number
  int            (16 bit)  -  [-32768 to 32767] signed number
  unsigned long  (32 bit)  -  [0-4,294,967,295] unsigned number usually for millis
  long           (32 bit)  -  [-2,147,483,648 to 2,147,483,647] signed number
  float          (32 bit)  -  [-3.4028235E38 to 3.4028235E38] signed number
  uint8_t        (8 bit)   -  [0-255] unsigned number
  int8_t         (8 bit)   -  [-127 - 127] signed number
  uint16_t       (16 bit)  -  [0-65,535] unsigned number
  int16_t        (16 bit)  -  [-32,768 - 32,767] signed number
  uint32_t       (32 bit)  -  [0-4,294,967,295] unsigned number
  int32_t        (32 bit)  -  [-2,147,483,648 - 2,147,483,647] signed number
  uint64_t       (64 bit)  -  [0-18,446,744,073,709,551,615] unsigned number
  int64_t        (64 bit)  -  [−9,223,372,036,854,775,808 - 9,223,372,036,854,775,807] signed number
  --------------------------------------------*/
  
#define led (13)

unsigned long currentMillis;

//------- first timer stuff --------
const unsigned long onTime = 1000;
const unsigned long offTime = 2000;
unsigned long previousMillis = 0;
unsigned long interval = onTime;
boolean triggerState = true;
//------- end first timer stuff --------

void setup() {
  delay(2000);
  Serial.begin(115200);
  pinMode(led, OUTPUT);
}

void loop() {
  checkTimer();
}

void checkTimer() {
  digitalWrite(led, triggerState);
  currentMillis = millis();
  if ((unsigned long)(currentMillis - previousMillis) >= interval) {
    if (triggerState) {
      interval = offTime;
      Serial.println("LED1 off");
      digitalWrite(led, LOW);   // turn the LED on (HIGH is the voltage level)
    } else {
      interval = onTime;
      Serial.println("LED1 on");
      digitalWrite(led, HIGH);   // turn the LED on (HIGH is the voltage level)
    }
    triggerState = !(triggerState);
    previousMillis = currentMillis;
  }
}