leds/lcd_manager.py

from time import sleep


class Adafruit_CharLCD:

    # commands
    LCD_CLEARDISPLAY = 0x01
    LCD_RETURNHOME = 0x02
    LCD_ENTRYMODESET = 0x04
    LCD_DISPLAYCONTROL = 0x08
    LCD_CURSORSHIFT = 0x10
    LCD_FUNCTIONSET = 0x20
    LCD_SETCGRAMADDR = 0x40
    LCD_SETDDRAMADDR = 0x80

    # flags for display entry mode
    LCD_ENTRYRIGHT = 0x00
    LCD_ENTRYLEFT = 0x02
    LCD_ENTRYSHIFTINCREMENT = 0x01
    LCD_ENTRYSHIFTDECREMENT = 0x00

    # flags for display on/off control
    LCD_DISPLAYON = 0x04
    LCD_DISPLAYOFF = 0x00
    LCD_CURSORON = 0x02
    LCD_CURSOROFF = 0x00
    LCD_BLINKON = 0x01
    LCD_BLINKOFF = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE = 0x08
    LCD_CURSORMOVE = 0x00

    # flags for display/cursor shift
    LCD_DISPLAYMOVE = 0x08
    LCD_CURSORMOVE = 0x00
    LCD_MOVERIGHT = 0x04
    LCD_MOVELEFT = 0x00

    # flags for function set
    LCD_8BITMODE = 0x10
    LCD_4BITMODE = 0x00
    LCD_2LINE = 0x08
    LCD_1LINE = 0x00
    LCD_5x10DOTS = 0x04
    LCD_5x8DOTS = 0x00

    def __init__(self, pin_rs=24, pin_e=23, pin_b=4, pins_db=[17, 25, 27, 22], GPIO=None):
        # Emulate the old behavior of using RPi.GPIO if we haven't been given
        # an explicit GPIO interface to use
        if not GPIO:
            import RPi.GPIO as GPIO
        self.GPIO = GPIO
        self.pin_rs = pin_rs
        self.pin_e = pin_e
        self.pin_b = pin_b
        self.pins_db = pins_db

        self.GPIO.setwarnings(False)
        self.GPIO.setmode(GPIO.BCM)
        self.GPIO.setup(self.pin_e, GPIO.OUT)
        self.GPIO.setup(self.pin_rs, GPIO.OUT)
        self.GPIO.setup(self.pin_b, GPIO.OUT)

        for pin in self.pins_db:
            self.GPIO.setup(pin, GPIO.OUT)

        self.GPIO.output(self.pin_b, True)

        self.write4bits(0x33)  # initialization
        self.write4bits(0x32)  # initialization
        self.write4bits(0x28)  # 2 line 5x7 matrix
        self.write4bits(0x0C)  # turn cursor off 0x0E to enable cursor
        self.write4bits(0x06)  # shift cursor right

        self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF

        self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
        self.displayfunction |= self.LCD_2LINE

        """ Initialize to default text direction (for romance languages) """
        self.displaymode = self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
        self.write4bits(self.LCD_ENTRYMODESET |
                        self.displaymode)  # set the entry mode

        self.clear()

    def begin(self, cols, lines):

        if (lines > 1):
            self.numlines = lines
            self.displayfunction |= self.LCD_2LINE
            self.currline = 0

    def home(self):

        self.write4bits(self.LCD_RETURNHOME)  # set cursor position to zero
        self.delayMicroseconds(3000)  # this command takes a long time!

    def clear(self):

        self.write4bits(self.LCD_CLEARDISPLAY)  # command to clear display
        # 3000 microsecond sleep, clearing the display takes a long time
        self.delayMicroseconds(3000)

    def setCursor(self, col, row):

        self.row_offsets = [0x00, 0x40, 0x14, 0x54]

        if (row > self.numlines):
            row = self.numlines - 1  # we count rows starting w/0

        self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))

    def noDisplay(self):
        """ Turn the display off (quickly) """
        self.GPIO.output(self.pin_b, False)
        self.displaycontrol &= ~self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def display(self):
        """ Turn the display on (quickly) """
        self.GPIO.output(self.pin_b, True)
        self.displaycontrol |= self.LCD_DISPLAYON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noCursor(self):
        """ Turns the underline cursor on/off """

        self.displaycontrol &= ~self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def cursor(self):
        """ Cursor On """

        self.displaycontrol |= self.LCD_CURSORON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noBlink(self):
        """ Turn on and off the blinking cursor """

        self.displaycontrol &= ~self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def noBlink(self):
        """ Turn on and off the blinking cursor """

        self.displaycontrol &= ~self.LCD_BLINKON
        self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

    def DisplayLeft(self):
        """ These commands scroll the display without changing the RAM """

        self.write4bits(self.LCD_CURSORSHIFT |
                        self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)

    def scrollDisplayRight(self):
        """ These commands scroll the display without changing the RAM """

        self.write4bits(self.LCD_CURSORSHIFT |
                        self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT)

    def leftToRight(self):
        """ This is for text that flows Left to Right """

        self.displaymode |= self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def rightToLeft(self):
        """ This is for text that flows Right to Left """
        self.displaymode &= ~self.LCD_ENTRYLEFT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def autoscroll(self):
        """ This will 'right justify' text from the cursor """

        self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def noAutoscroll(self):
        """ This will 'left justify' text from the cursor """

        self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
        self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)

    def write4bits(self, bits, char_mode=False):
        """ Send command to LCD """

        self.delayMicroseconds(1000)  # 1000 microsecond sleep

        bits = bin(bits)[2:].zfill(8)

        self.GPIO.output(self.pin_rs, char_mode)

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i], True)

        self.pulseEnable()

        for pin in self.pins_db:
            self.GPIO.output(pin, False)

        for i in range(4, 8):
            if bits[i] == "1":
                self.GPIO.output(self.pins_db[::-1][i-4], True)

        self.pulseEnable()

    def delayMicroseconds(self, microseconds):
        # divide microseconds by 1 million for seconds
        seconds = microseconds / float(1000000)
        sleep(seconds)

    def pulseEnable(self):
        self.GPIO.output(self.pin_e, False)
        # 1 microsecond pause - enable pulse must be > 450ns
        self.delayMicroseconds(1)
        self.GPIO.output(self.pin_e, True)
        # 1 microsecond pause - enable pulse must be > 450ns
        self.delayMicroseconds(1)
        self.GPIO.output(self.pin_e, False)
        self.delayMicroseconds(1)   # commands need > 37us to settle

    def message(self, text):
        """ Send string to LCD. Newline wraps to second line"""

        for char in text:
            if char == '\n':
                self.write4bits(0xC0)  # next line
            else:
                self.write4bits(ord(char), True)