树莓派 1602A显示屏

## based on code from lrvick and LiquidCrystal# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp#

from time import sleep

class lcd1602:

# 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=14, pin_e=15, pins_db=[17, 18, 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.pins_db = pins_db

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

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

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 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 - 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.displaycontrol &= ~self.LCD_DISPLAYON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)

def display(self): """ Turn the display on (quickly) """

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

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

if __name__ == '__main__':

lcd = lcd1602() lcd.clear() lcd.message("hello world!")