void HardwareSerial::end()
{
// wait for transmission of outgoing data
while (_tx_buffer->head != _tx_buffer->tail)
;
cbi(*_ucsrb, _rxen);
cbi(*_ucsrb, _txen);
cbi(*_ucsrb, _rxcie);
cbi(*_ucsrb, _udrie);
// clear any received data
_rx_buffer->head = _rx_buffer->tail;
}
