allow serial baudrate and show usage in example

README.md

@@ -5,6 +5,6 @@ alphasign is a Python library for
 [Betabrite](http://www.betabrite.com/). It implements the
 [Alpha Communications Protocol](http://www.alpha-american.com/p-alpha-communications-protocol.html).
 
-[Read the Docs](http://readthedocs.org/docs/alphasign)
+[Read the Docs](https://alphasign.readthedocs.io/en/latest/)
 
 ![Betabrite Prisom displaying the time and temperature updated by a program using the alphasign library.](http://farm9.staticflickr.com/8010/7151560649_2d5f04955b.jpg)

alphasign/__init__.py

@@ -7,6 +7,7 @@
 
   def main():
     sign = alphasign.USB(alphasign.devices.USB_BETABRITE_PRISM)
+    # sign = alphasign.interfaces.local.Serial(device='/dev/ttyUSB0', baudrate=38400) # serial version
     sign.connect()
     sign.clear_memory()
 

alphasign/interfaces/local.py

@@ -10,12 +10,15 @@ class Serial(base.BaseInterface):
 
   This class uses `pySerial <http://pyserial.sourceforge.net/>`_.
   """
-  def __init__(self, device="/dev/ttyS0"):
+  def __init__(self, device="/dev/ttyS0", baudrate=4800):
     """
     :param device: character device (default: /dev/ttyS0)
     :type device: string
+    :param baudrate: baudrate (default: 4800) 
+    :type baudrate: integer
     """
     self.device = device
+    self.baudrate = baudrate
     self.debug = True
     self._conn = None
 
@@ -25,7 +28,7 @@ def connect(self):
     # TODO(ms): these settings can probably be tweaked and still support most of
     # the devices.
     self._conn = serial.Serial(port=self.device,
-                               baudrate=4800,
+                               baudrate=self.baudrate,
                                parity=serial.PARITY_EVEN,
                                stopbits=serial.STOPBITS_TWO,
                                bytesize=serial.SEVENBITS,