!
        GPIO initialization.
        Set GPIO into BCM mode and init other IOs mode

def _init_io(self):
        """!
        GPIO initialization.
        Set GPIO into BCM mode and init other IOs mode
        """
        GPIO.setwarnings(False)
        GPIO.setmode( GPIO.BCM )
        pins = [ self._spi_dc ]
        for pin in pins:
            GPIO.setup( pin, GPIO.OUT )