#include "esp32-hal-timer.h"

hw_timer_t *timer1 = NULL;

void IRAM_ATTR blinkLED() {
  digitalWrite(23, !digitalRead(23));
  Serial.printf("[%ld]: %s\n", millis(), __func__);
}

void setup() {
  Serial.begin(115200);
  Serial.println("Lab 5.4");
  pinMode(23, OUTPUT);           // Red LED
  pinMode(22, OUTPUT);           // Blue LED
  pinMode(32, INPUT_PULLDOWN);   // Pushbutton

  timer1 = timerBegin(1000000);  // 1 MHz -> 1 microseconds
  if (timer1 == NULL) {
    Serial.println("Timer initialization failed!");
    while(1); // Stop if timer failed
  }
  timerAttachInterrupt(timer1, &blinkLED);
  timerWrite(timer1, 0);  // Reset the alarm
  timerAlarm(timer1, 5000000, true, 0); // 5 s, autoreload 
  // timer1 is automatically started by timerAlarm()
}

void loop() {
  // Switch blue LED based on pushbutton
  digitalWrite(22, digitalRead(32));
}