HC595_One_Pin

//-------------------------
void setup()
{
  pinMode(2, OUTPUT);
  digitalWrite(3, LOW);
}
//------------------------
void loop()
{
  for (int i = 0; i < 24; i++)        // 24 bits  = 3 x HC595
    {
     BitOn();
     delay(50);
    }
    for (int i = 0; i < 24; i++)       // 24 bits  = 3 x HC595
    {
     BitOff();
     delay(50);
    }
}
//---------------------------
void BitOn()
{
  digitalWrite(2, LOW);           // Down port
  delayMicroseconds(25);          // bit On  minimo 20 us maximo 70
  digitalWrite(2, HIGH);          // Upper port
  delayMicroseconds(50);          // Tempo minimo 50us
}
//---------------------------
void BitOff()
{
  digitalWrite(2, LOW);           // Upper port
  delayMicroseconds(120);         // bit off minimo 100 us maximo não tem
  digitalWrite(2, HIGH);          // Upper port
  delayMicroseconds(50);          // Tempo minimo 50us
}