Parameters
        ----------
        port : str or list-like, optional
            Port (or list of ports) to try to connect to as a DMF Control
            Board.
        baud_rate : int, optional

        Returns
        -------
        str
            Port DMF control board was connected on.

        Raises
        ------
        RuntimeError
            If connection could not be established.
        IOError
            If no ports were specified and Arduino Mega2560 not found on any
            port.

def connect(self, port=None, baud_rate=115200):
        '''
        Parameters
        ----------
        port : str or list-like, optional
            Port (or list of ports) to try to connect to as a DMF Control
            Board.
        baud_rate : int, optional

        Returns
        -------
        str
            Port DMF control board was connected on.

        Raises
        ------
        RuntimeError
            If connection could not be established.
        IOError
            If no ports were specified and Arduino Mega2560 not found on any
            port.
        '''
        if isinstance(port, types.StringTypes):
            ports = [port]
        else:
            ports = port

        if not ports:
            # No port was specified.
            #
            # Try ports matching Mega2560 USB vendor/product ID.
            ports = serial_ports().index.tolist()
            if not ports:
                raise IOError("Arduino Mega2560 not found on any port.")

        for comport_i in ports:
            if self.connected():
                self.disconnect()
                self.port = None
                self._i2c_devices = {}

            # Try to connect to control board on available ports.
            try:
                logger.debug('Try to connect to: %s', comport_i)
                # Explicitly cast `comport_i` to string since `Base.connect`
                # Boost Python binding does not support unicode strings.
                #
                # Fixes [issue 8][issue-8].
                #
                # [issue-8]: https://github.com/wheeler-microfluidics/dmf-control-board-firmware/issues/8
                Base.connect(self, str(comport_i), baud_rate)
                self.port = comport_i
                break
            except BadVGND, exception:
                logger.warning(exception)
                break
            except RuntimeError, exception:
                continue
        else:
            raise RuntimeError('Could not connect to control board on any of '
                               'the following ports: %s' % ports)

        name = self.name()
        version = self.hardware_version()
        firmware = self.software_version()
        serial_number_string = ""
        try:
            serial_number_string = ", S/N %03d" % self.serial_number
        except:
            # Firmware does not support `serial_number` attribute.
            pass
        logger.info("Connected to %s v%s (Firmware: %s%s)" %
                    (name, version, firmware, serial_number_string))

        logger.info("Poll control board for series resistors and "
                    "capacitance values.")

        self._read_calibration_data()

        try:
            self.__aref__ = self._aref()
            logger.info("Analog reference = %.2f V" % self.__aref__)
        except:
            # Firmware does not support `__aref__` attribute.
            pass

        # Check VGND for both analog channels
        expected = 2 ** 10/2
        v = {}
        channels = [0, 1]
        damaged = []
        for channel in channels:
            try:
                v[channel] = np.mean(self.analog_reads(channel, 10))
                logger.info("A%d VGND = %.2f V (%.2f%% of Aref)", channel,
                            self.__aref__ * v[channel] / (2 ** 10), 100.0 *
                            v[channel] / (2 ** 10))
                # Make sure that the VGND is close to the expected value;
                # otherwise, the op-amp may be damaged (expected error
                # is <= 10%).
                if np.abs(v[channel] - expected) / expected > .1:
                    damaged.append(channel)
            except:
                # Firmware does not support `__aref__` attribute.
                break

        # Scan I2C bus to generate list of connected devices.
        self._i2c_scan()

        if damaged:
            # At least one of the analog input channels appears to be damaged.
            if len(damaged) == 1:
                msg = "Analog channel %d appears" % damaged[0]
            else:
                msg = "Analog channels %s appear" % damaged
            raise BadVGND(msg + " to be damaged. You may need to replace the "
                          "op-amp on the control board.")

        return self.RETURN_OK