const uint8_t switches_pins[] = { 9, 8, 7, 6, 5, 4, 3, 2 };


void setup()
{
  Serial.begin( 115200 );

  for ( uint8_t i = 0; i < 8; ++i )
  {
    pinMode( switches_pins[i], INPUT_PULLUP );
  }
}


void loop()
{
  uint8_t address = 0;

  for ( uint8_t i = 0; i < 8; ++i )
  {
    if ( digitalRead( switches_pins[i] ) == LOW )
    {
      address |= 1 << ( 7 - i );
    }
  }

  static uint8_t address_previous = !address;
  
  if ( address_previous != address )
  {
    address_previous = address;
    Serial.print( "Address changed : " );
    for ( uint8_t i = 0b10000000; i > 0; i >>= 1 )
    {
      Serial.print( ( address & i ) != 0 );
    }
    Serial.println();
  }
}