/*
  Blink BUILTIN LED example

  Author: Alexander Popov
  License: Unlicense
*/

int user_input;
int delay_time = 1000;
bool led_state = HIGH;
unsigned long timer = 0;

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // read blink delay
  if (Serial.available()) {
    user_input = Serial.parseInt();
    if (user_input >= 100) {
      delay_time = user_input;

      Serial.print("Delay set to ");
      Serial.print(user_input);
      Serial.println(" ms");
    }
    else if (user_input > 0 && user_input < 100) {
      Serial.println("Error: set delay time >=100ms");
    }
  }

  // blink LED
  if (millis() - timer > delay_time) {
    led_state =! led_state;
    digitalWrite(LED_BUILTIN, led_state);

    timer = millis();
  }
}