Matrix Orbital Python Class

gistfile1.py

import os
import re
import serial
import sys
import thread
import time

class Display():
    '''
    Display class for Matrix Orbital MX LCD Screens.
    Essentially a wrapper for serial.Serial with Matrix Orbital functions.
    >>> d = Display(2)
    >>> d.clear()
    >>> d.send("Hello World!")
    '''
    #constants
    ## basic utils
    NULL = '\x00'
    CLEAR = '\xfe\x58'
    CMD = '\xfe'
    BACKLIGHT_ON = '\xfe\x42\x00'
    BACKLIGHT_OFF = '\xfe\x46'
    ## bar graphs
    INIT_VBG_THIN = '\xfe\x73'
    INIT_VBG_THICK = '\xfe\x76'
    INIT_HBG = '\xfe\x68'
    ## input
    KEYS_IN = []
    LISTEN_FOR_KEYS = True

    def clear(self):
        '''Clears the screen'''
        self.send(self.CLEAR)
   
    def __init__(self, port, baud=19200):
        self._serial = serial.Serial(port, baud)
        self.clear()

    def send(self, data):
        '''Wrapper for our serial instance's write method'''
        self._serial.write(data)

    def close(self):
        '''Wrapper for our serial instance's close method'''
        self._serial.close()

    def draw_vbg(self, cols=[], kind="thin"):
        '''Method to draw a vertical bar graph
        cols is an array of two-tuples [(column, height)]
        example usage:
            my_display.draw_vbg([(1,2),(2,4),(3,6)])
        The example would draw a bar graph with bars on
        columns 1, 2, & 3 with heights 2, 4, & 6 (respectively)
        '''
        if kind == "thin":
            self.send(self.INIT_VBG_THIN)
        else:
            self.send(self.INIT_VBG_THICK)

        for col in cols:
            c = int(col[0]) # column to draw
            h = int(col[1]) # height of bar (0-14?)
            try:
                self.send(self.CMD+'\x3d'+chr(c)+chr(h))
            except:
                raise

    def clear_keys(self):
        '''Clears out the KEYS_IN array'''
        self.KEYS_IN = []

    # should not be called outside of class! use key_listen()
    def _thread_key_listen(self):
        while self.LISTEN_FOR_KEYS:
            key = self._serial.read()
            self.KEYS_IN.append(key)
        #clean up on fail or exit
        self.key_listen_thread = None
 
    def key_listen(self):
        '''starts a new thread to listen for key presses and
        inserts them into the KEYS_IN array'''
        self.key_listen_thread = thread.start_new_thread(self._thread_key_listen, ())