// https://microcontrollerslab.com/esp32-pinout-use-gpio-pins/

// https://github.com/espressif/arduino-esp32
// https://github.com/espressif/arduino-esp32/tree/master/cores/esp32

// https://github.com/johnrickman/LiquidCrystal_I2C

//--------------------------------------------------
//--------------------------------------------------
// Includes:
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

//--------------------------------------------------
// Globals:

volatile int32_t gCounter = 0; // global volatile variable

// LCD Objekt erzeugen
// - I2C Adresse: 0x27
// - Zeichen pro Zeile: 16
// - Anzahl Zeilen: 2
LiquidCrystal_I2C myLCD = LiquidCrystal_I2C(0x27, 16, 2);

//--------------------------------------------------
// Interrupt Service Routine for pin 34
void IRAM_ATTR ISR_34() {
  gCounter++; // increase global counter
}

// Interrupt Service Routine for pin 35
void IRAM_ATTR ISR_35() {
  gCounter--; // decrease global counter
}

//--------------------------------------------------
void setup() {
  //---
  // Init USART:
  Serial.begin(115200);
  Serial.println("Hallo BBW !!!");

  //---
  // Init LCD:
  myLCD.init();
  myLCD.backlight();

  //---
  // Init Pin 34 als INPUT mit internem Pulldown-Widerstand.
  // Der Default-Zustand am Pin ist so LOW.
  pinMode(34, INPUT_PULLDOWN);

  // Init Pin 35 als INPUT mit internem Pulldown-Widerstand.
  // Der Default-Zustand am Pin ist so LOW.
  pinMode(35, INPUT_PULLDOWN);

  // Attach interrupt for pin 34 to interrupt function ISR_34
  attachInterrupt(digitalPinToInterrupt(34), ISR_34, RISING);

  // Attach interrupt for pin 35 to interrupt function ISR_35
  attachInterrupt(digitalPinToInterrupt(35), ISR_35, RISING);
}

//--------------------------------------------------
void loop() {

  // Wait 500ms (2Hz)
  delay(500);

  // Output gCounter to USART
  Serial.print("gCounter = ");
  Serial.println(gCounter);

  // Output gCounter to LCD
  myLCD.setCursor(15, 0); // set cursor to last position of first line
  myLCD.printf("%6d", gCounter); // print gCounter with 6 digits, right aligned
}