BBC Micro:Bit 16x2 Character LCD

BBC_LCD.py

from microbit import *

# pin connections
rs = pin0
enable = pin1
datapins = [pin8, pin12, pin2, pin13]
button1 = pin5
# 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
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 InitDisplay():
    # at least 50ms after power on
    sleep(50)
    # send rs, enable low - rw is tied to GND
    rs.write_digital(0)
    enable.write_digital(0)
    write4bits(0x03)
    sleep(5)
    write4bits(0x03)
    sleep(5)
    write4bits(0x03)
    sleep(2)
    write4bits(0x02)
    send(LCD_FUNCTIONSET | 0x08, 0)
    sleep(5)
    send(LCD_FUNCTIONSET | 0x08, 0)
    sleep(2)
    send(LCD_FUNCTIONSET | 0x08, 0)
    sleep(2)
    send(LCD_FUNCTIONSET | 0x08, 0)
    sleep(2)
    send(LCD_DISPLAYCONTROL | LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF,0)
    clear()
    send(LCD_ENTRYMODESET | LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT,0)
     
# high level commands    
def clear():
    send(LCD_CLEARDISPLAY,0)
    sleep(2)

def home():
    send(LCD_RETURNHOME,0)
    sleep(2)

def setCursor(col, row):
    orpart = col
    if row>0:
        orpart = orpart + 0x40
    send(LCD_SETDDRAMADDR | orpart, 0)

def showText(t):
    for c in t:
        send(ord(c), 1)
                
def send(value, mode):
    rs.write_digital(mode)
    write4bits(value>>4)
    write4bits(value)
    
def pulseEnable():
    enable.write_digital(0)
    sleep(1)
    enable.write_digital(1)
    sleep(1)
    enable.write_digital(0)
    sleep(1)

def write4bits(value):
    for i in range(0,4):
        datapins[i].write_digital((value>>i) & 0x01)
    pulseEnable()


# Start Display   
InitDisplay()  # Initialise LCD - 2 lines, 4 bit mode
while True:
    if not button1.read_digital():       
        setCursor(1,0)                  # (column,line)
        showText("BBC Micro:Bit")
        sleep(500)
    if button1.read_digital():       
        setCursor(1,0)
        showText("CHARACTER LCD")
        sleep(500)