gistfile1.txt

import logging
import logging.handlers
import logging.config
import threading
import time
import string
import serial

class SBLCD():
    logger = logging.getLogger('SBLCD')
    def __init__(self,port, baudrate, bytesize, parity, stopbits, backlight=True, brightness=100):
        self.port=port
        self.baudrate=int(baudrate)
        self.bytesize=int(bytesize)       
        self.parity=parity
        self.stopbits=int(stopbits)
        self.backlight=backlight 
        self.brightness=brightness
        self.ser_buffer=['']
        self.writelock=False
      
        try:
            self.ser = serial.Serial(port, baudrate, bytesize, parity, stopbits)
        except Exception as e:
            self.ser = serial.Serial()
            self.logger.warning('Unable to open serial connection to the LCD.')

        self.setBrightness(brightness)
        if(backlight):
            self.backlightOn()
        else:
            self.backlightOff()
            
        self.drawthread = threading.Thread(name='drawthread', target=self.draw)
        self.drawthread.setDaemon(True)

    def start(self):

        if (not self.drawthread.isAlive()):
            self.drawthread.start()          
            return True
        else:
            return False

    def stop(self):
        if (self.drawthread.isAlive()):
            self.drawthread.stop()
            self.ser.close()
            return True
        else:
            return False

    def draw (self):
        while True:
            if (len(self.ser_buffer) > 0):
                tmp=self.ser_buffer[0]
                self.ser_buffer.pop(0)

                if (tmp == '\xFE\x58' and len(self.ser_buffer) > 0):
                    tmp+=self.ser_buffer[0]
                    self.ser_buffer.pop(0)
                    
                self.writeSerial(tmp)
            time.sleep(0.1)

    def isBacklightOn(self):
        return self.backlight

    def getBrightness(self):
        return self.brightness

    def backlightOn(self):
        self.backlight = True
        self.writeBuffer('\xFE\x42')

    def backlightOff(self):
        self.backlight = False
        self.writeBuffer('\xFE\x46')

    def setBrightness(self,percent):
        self.brightness = percent
        self.writeBuffer("\xFE\x99%c" % chr(int((float(percent)/100) * 255)))

    def setWriteLock(self):
        while self.writelock:
            time.sleep(0.1)
        self.writelock=True


    def unsetWriteLock(self):
        self.writelock=False

    def writeBuffer(self,data):
        self.ser_buffer.append(data)

    def writeSerial(self,data):
        self.setWriteLock()

        if (not self.ser.isOpen()):
            try:
                self.ser.open()
            except:
                pass
                
        try:
            self.ser.write(data + '\r')
            self.ser.flush()
        except Exception as e:
            pass
        self.unsetWriteLock()

    def clearScreen(self):
        self.writeBuffer('\xFE\x58')

    def getPositionCode(self,row,col):
        return '\xFE\x47' + chr(col) + chr(row)