#include "Wire.h"

#define ADDR 0x20

uint8_t writeBits = 0x00;
uint8_t readBits = 0x00;
uint8_t writeByte = 0x00;
uint8_t readByte = 0x00;
bool ascending = true; // Controla si el conteo es ascendente o descendente

void init_pcf8574() {
  Wire.begin(21, 22);
  Wire.beginTransmission(ADDR);
  uint8_t registers = writeBits;
  Wire.write(~registers);
  Serial.println("writed");
  Serial.println(registers);
  Wire.endTransmission();
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);

  writeBits = 0b11111111;
  init_pcf8574();
  delay(1000);
  writeByte = 0;
}

void loop() {
  Wire.beginTransmission(ADDR);

  // Verificar el límite y cambiar la dirección
  if (ascending) {
    writeByte++;
    if (writeByte == 0xFF) {
      ascending = false; // Cambiar a descendente al alcanzar el máximo
    }
  } else {
    writeByte--;
    if (writeByte == 0x00) {
      ascending = true; // Cambiar a ascendente al alcanzar el mínimo
    }
  }

  Wire.write(writeByte);
  Wire.endTransmission();
  delay(100);
}