LCD with PFC8547 I2C expander/backpack

Author: tdack

Adafruit_PFC8547LCD/Adafruit_I2C.py

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+../Adafruit_I2C/Adafruit_I2C.py

Adafruit_PFC8547LCD/Adafruit_PFC8547LCD.py

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+from time import sleep
+from Adafruit_I2C import Adafruit_I2C
+
+# Code based on https://gist.github.com/ufux/6094977
+# Massaged to use Adafruit_I2C library and commands.
+# Communication from expander to display: high nibble first, then low nibble
+# Communication via i2c to the PCF 8547: bits are processed from highest to lowest (send P7 bit first)
+
+class Adafruit_PCF8547LCD:
+    #initializes objects and lcd
+
+    # LCD 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 on/off control
+    LCD_DISPLAYON           = 0x04
+    LCD_DISPLAYOFF          = 0x00
+    LCD_CURSORON            = 0x02
+    LCD_CURSOROFF           = 0x00
+    LCD_BLINKON             = 0x01
+    LCD_BLINKOFF            = 0x00
+
+    # Flags for display entry mode
+    LCD_ENTRYRIGHT          = 0x00
+    LCD_ENTRYLEFT           = 0x02
+    LCD_ENTRYSHIFTINCREMENT = 0x01
+    LCD_ENTRYSHIFTDECREMENT = 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
+
+    # flags for backlight control
+    LCD_BACKLIGHT = 0x08
+    LCD_NOBACKLIGHT = 0x00
+
+    EN = 0b00000100  # Enable bit
+    RW = 0b00000010  # Read/Write bit
+    RS = 0b00000001  # Register select bit
+
+    '''
+    new pinout:
+    -----------    -----------
+    0x80    P7 -  - D7
+    0x40    P6 -  - D6
+    0x20    P5 -  - D5
+    0x10    P4 -  - D4
+    -----------    -----------
+    0x08    P3 -  - BL   Backlight ???
+    0x04    P2 -  - EN   Starts Data read/write
+    0x02    P1 -  - RW   low: write, high: read
+    0x01    P0 -  - RS   Register Select: 0: Instruction Register (IR) (AC when read), 1: data register (DR)
+    '''
+
+    def __init__(self, addr=0x3f, busnum=-1, withBacklight=True, withOneTimeInit=False):
+        '''
+        device writes!
+        crosscheck also http://www.monkeyboard.org/tutorials/81-display/70-usb-serial-to-hd44780-lcd
+        here a sequence is listed
+        '''
+        self.addr = addr
+        self.busnum = busnum
+
+        self.bus = Adafruit_I2C(self.addr, self.busnum)
+
+        self.displayshift   = (self.LCD_CURSORMOVE |
+                               self.LCD_MOVERIGHT)
+        self.displaymode    = (self.LCD_ENTRYLEFT |
+                               self.LCD_ENTRYSHIFTDECREMENT)
+        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
+
+        if withBacklight:
+            self.blFlag=self.LCD_BACKLIGHT
+        else:
+            self.blFlag=self.LCD_NOBACKLIGHT
+
+        # we can initialize the display only once after it had been powered on
+        if(withOneTimeInit):
+            self.bus.writeRaw8(0x3f)
+            self.pulseEnable()
+            sleep(0.0100) # TODO: Not clear if we have to wait that long
+        self.write(self.displayfunction) # 0x28
+
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)   # 0x08 + 0x4 = 0x0C
+        self.write(self.LCD_ENTRYMODESET   | self.displaymode)      # 0x06
+        self.clear()                           # 0x01
+        self.home()
+
+    def begin(self, cols, lines):
+        if (lines > 1):
+            self.numlines = lines
+            self.displayfunction |= self.LCD_2LINE
+
+    def home(self):
+        self.write(self.LCD_RETURNHOME)  # set cursor position to zero
+        self.delayMicroseconds(3000)  # this command takes a long time!
+
+    def clear(self):
+        self.write(self.LCD_CLEARDISPLAY)  # command to clear display
+        self.delayMicroseconds(3000)  # 3000 microsecond sleep, clearing the display takes a long time
+
+    def setCursor(self, col, row):
+        self.row_offsets = [0x00, 0x40, 0x14, 0x54]
+        if row > self.numlines:
+            row = self.numlines
+        row -= 1 # row_offsets is zero indexed
+        self.write(self.LCD_SETDDRAMADDR | (col - 1 + self.row_offsets[row]))
+
+    def noDisplay(self):
+        """ Turn the display off (quickly) """
+        self.displaycontrol &= ~self.LCD_DISPLAYON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def display(self):
+        """ Turn the display on (quickly) """
+        self.displaycontrol |= self.LCD_DISPLAYON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def noCursor(self):
+        """ Turns the underline cursor off """
+        self.displaycontrol &= ~self.LCD_CURSORON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def cursor(self):
+        """ Turns the underline cursor on """
+        self.displaycontrol |= self.LCD_CURSORON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def noBlink(self):
+        """ Turn the blinking cursor off """
+        self.displaycontrol &= ~self.LCD_BLINKON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def blink(self):
+        """ Turn the blinking cursor on """
+        self.displaycontrol |= self.LCD_BLINKON
+        self.write(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+    def DisplayLeft(self):
+        """ These commands scroll the display without changing the RAM """
+        self.write(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)
+
+    def scrollDisplayRight(self):
+        """ These commands scroll the display without changing the RAM """
+        self.write(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.write(self.LCD_ENTRYMODESET | self.displaymode)
+
+    def rightToLeft(self):
+        """ This is for text that flows Right to Left """
+        self.displaymode &= ~self.LCD_ENTRYLEFT
+        self.write(self.LCD_ENTRYMODESET | self.displaymode)
+
+    def autoscroll(self):
+        """ This will 'right justify' text from the cursor """
+        self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
+        self.write(self.LCD_ENTRYMODESET | self.displaymode)
+
+    def noAutoscroll(self):
+        """ This will 'left justify' text from the cursor """
+        self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
+        self.write(self.LCD_ENTRYMODESET | self.displaymode)
+
+    def delayMicroseconds(self, microseconds):
+        seconds = microseconds / float(1000000)  # divide microseconds by 1 million for seconds
+        sleep(seconds)
+
+    # clocks EN to latch command
+    def pulseEnable(self):
+        # uses underlying
+        self.bus.writeRaw8((self.bus.bus.read_byte(self.addr) | self.EN | self.blFlag)) # | 0b0000 0100 # set "EN" high
+        self.bus.writeRaw8(((self.bus.bus.read_byte(self.addr) | self.blFlag) & 0xFB)) # & 0b1111 1011 # set "EN" low
+
+    # write data to lcd in 4 bit mode, 2 nibbles
+    # high nibble is sent first
+    def write(self, cmd):
+        #write high nibble first
+        self.bus.writeRaw8( (cmd & 0xF0) | self.blFlag )
+        hi= self.bus.bus.read_byte(self.addr)
+        self.pulseEnable()
+
+        # write low nibble second ...
+        self.bus.writeRaw8( (cmd << 4) | self.blFlag )
+        lo= self.bus.bus.read_byte(self.addr)
+        self.pulseEnable()
+        self.bus.writeRaw8(self.blFlag)
+
+    # write a character to lcd (or character rom) 0x09: backlight | RS=DR
+    def write_char(self, charvalue):
+        controlFlag = self.blFlag | self.RS
+
+        # write high nibble
+        self.bus.writeRaw8((controlFlag | (charvalue & 0xF0)))
+        self.pulseEnable()
+
+        # write low nibble
+        self.bus.writeRaw8((controlFlag | (charvalue << 4)))
+        self.pulseEnable()
+        self.bus.writeRaw8(self.blFlag)
+
+    # put char function
+    def putc(self, char):
+        self.write_char(ord(char))
+
+    def _setDDRAMAdress(self, line, col):
+        # we write to the Data Display RAM (DDRAM)
+        # TODO: Factor line offsets for other display organizations; this is for 20x4 only
+        if line == 1:
+            self.write(self.LCD_SETDDRAMADDR | (0x00 + col) )
+        if line == 2:
+            self.write(self.LCD_SETDDRAMADDR | (0x40 + col) )
+        if line == 3:
+            self.write(self.LCD_SETDDRAMADDR | (0x14 + col) )
+        if line == 4:
+            self.write(self.LCD_SETDDRAMADDR | (0x54 + col) )
+
+    # put string function
+    def message(self, string, line=1):
+        """ Send string to LCD.  Newline wraps to next line.
+            Starts at line 1 unless passed starting line """
+        self._setDDRAMAdress(line, 0)
+        for char in string:
+            if char == '\n':
+                line = 1 if line > 4 else line + 1
+                self._setDDRAMAdress(line, 0)
+            else:
+                self.putc(char)
+
+    def putString(self, string):
+        """ Sends a string to LCD starting at current cursor position
+            Doesn't handle newline character
+        """
+        for char in string:
+            self.putc(char)
+
+    # add custom characters (0 - 7)
+    def lcd_load_custon_chars(self, fontdata):
+        self.lcd_device.bus.write(0x40);
+        for char in fontdata:
+            for line in char:
+                self.write_char(line)
+
+if __name__ == '__main__':
+    from time import localtime, strftime
+
+    initFlag=False
+    debug=False
+    backlight=True
+
+    lcd = Adafruit_PCF8547LCD(0x3f,1,backlight, initFlag)
+    lcd.begin(20,4)
+    msg = "+" + "=" * 18 + "+\n"
+    msg += "|    20x4 LCD      |\n"
+    msg += "|   w/ PCF8547     |\n"
+    msg += "+" + "=" * 18 + "+"
+
+    lcd.message(msg)
+    sleep(3)
+
+    lcd.clear()
+    lcd.cursor()
+    lcd.message("Cursor Positioning")
+    lcd.setCursor(2,4)
+    lcd.putString(". <- (2,4)")
+    lcd.setCursor(6,2)
+    lcd.putString(". <- (6,2)")
+    lcd.setCursor(11,3)
+    lcd.putString(".")
+    lcd.setCursor(1,3)
+    lcd.putString("(11,3) -> ")
+
+    sleep(5)
+
+    lcd.clear()
+    lcd.noCursor()
+    lcd.message("    Simple Clock    ",1)
+    lcd.message("CTRL-C to quit",4)
+    while True:
+        lcd.message(strftime("%Y-%m-%d %H:%M:%S ", localtime()),3)
+        sleep(1)