#include "esp32-hal-timer.h"

hw_timer_t *timer = NULL;

void IRAM_ATTR blink() { digitalWrite(22, !digitalRead(22)); }

void setup() {
  Serial.begin(115200);
  Serial.println("Hello, ESP32");
  pinMode(23, OUTPUT);           // Red LED
  pinMode(22, OUTPUT);           // Blue LED
  pinMode(32, INPUT_PULLDOWN);   // Pushbutton

  timer = timerBegin(1000000);   // 1 microsecond
  if (timer == NULL) {
    Serial.println("Timer initialization failed!");
    while(1); // Stop if timer failed
  }
  timerAttachInterrupt(timer, &blink);  // Attach blink ISR
  timerWrite(timer, 0);                 // Reset count
  // Set alarm to trigger every 1 million ticks = 1s
  timerAlarm(timer, 1000000, true, 0);  
  timerStart(timer);                    // Start the timer
  Serial.println("Timer started");
}

void loop() {
  digitalWrite(23, digitalRead(32));
}