树莓派用Python写几个简单程序2_i2c-lcd

3. i2c LCD 2004 的使用

首先树莓派得安装 python-smbus, i2c-tools,

然后修改文件：sudo nano /etc/modules，添加上 i2c-bcm2708 和i2c-dev 这两行，Raspbian还需要在raspi-config中激活i2c.

用 sudo i2cdetect -y 1 查看设备地址，此处LCD地址0x27

主程序 lcd_main.py:

import i2c_lcddriver as lcd_driverfrom time import *lcd = lcd_driver.lcd()lcd.lcd_display_string("hello,raspberry", 1)

驱动程序 i2c_lcddriver.py:

import i2c_libfrom time import *# LCD AddressADDRESS = 0x3f# commandsLCD_CLEARDISPLAY = 0x01LCD_RETURNHOME = 0x02LCD_ENTRYMODESET = 0x04LCD_DISPLAYCONTROL = 0x08LCD_CURSORSHIFT = 0x10LCD_FUNCTIONSET = 0x20LCD_SETCGRAMADDR = 0x40LCD_SETDDRAMADDR = 0x80# flags for display entry modeLCD_ENTRYRIGHT = 0x00LCD_ENTRYLEFT = 0x02LCD_ENTRYSHIFTINCREMENT = 0x01LCD_ENTRYSHIFTDECREMENT = 0x00# flags for display on/off controlLCD_DISPLAYON = 0x04LCD_DISPLAYOFF = 0x00LCD_CURSORON = 0x02LCD_CURSOROFF = 0x00LCD_BLINKON = 0x01LCD_BLINKOFF = 0x00# flags for display/cursor shiftLCD_DISPLAYMOVE = 0x08LCD_CURSORMOVE = 0x00LCD_MOVERIGHT = 0x04LCD_MOVELEFT = 0x00# flags for function setLCD_8BITMODE = 0x10LCD_4BITMODE = 0x00LCD_2LINE = 0x08LCD_1LINE = 0x00LCD_5x10DOTS = 0x04LCD_5x8DOTS = 0x00# flags for backlight controlLCD_BACKLIGHT = 0x08LCD_NOBACKLIGHT = 0x00En = 0b00000100 # Enable bitRw = 0b00000010 # Read/Write bitRs = 0b00000001 # Register select bitclass lcd(object):    #initializes objects and lcd    def __init__(self):        self.lcd_device = i2c_lib.i2c_device(ADDRESS)        self.lcd_write(0x03)        self.lcd_write(0x03)        self.lcd_write(0x03)        self.lcd_write(0x02)        self.lcd_write(LCD_FUNCTIONSET | LCD_2LINE | LCD_5x8DOTS | LCD_4BITMODE)        self.lcd_write(LCD_DISPLAYCONTROL | LCD_DISPLAYON)        self.lcd_write(LCD_CLEARDISPLAY)           self.lcd_write(LCD_ENTRYMODESET | LCD_ENTRYLEFT)        sleep(0.2)       # clocks EN to latch command    def lcd_strobe(self, data):        self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT)        sleep(.0005)        self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT))        sleep(.0001)       def lcd_write_four_bits(self, data):        self.lcd_device.write_cmd(data | LCD_BACKLIGHT)        self.lcd_strobe(data)    # write a command to lcd    def lcd_write(self, cmd, mode=0):        self.lcd_write_four_bits(mode | (cmd & 0xF0))        self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))    # put string function    def lcd_display_string(self, string, line):        if line == 1:            self.lcd_write(0x80)        if line == 2:            self.lcd_write(0xC0)        if line == 3:            self.lcd_write(0x94)        if line == 4:            self.lcd_write(0xD4)        for char in string:            self.lcd_write(ord(char), Rs)    # clear lcd and set to home    def lcd_clear(self):        self.lcd_write(LCD_CLEARDISPLAY)        self.lcd_write(LCD_RETURNHOME)

i2c 库程序 i2c_lib.py:

import smbusfrom time import *class i2c_device:    def __init__(self, addr, port=1):        self.addr = addr        self.bus = smbus.SMBus(port)       # Write a single command    def write_cmd(self, cmd):        self.bus.write_byte(self.addr, cmd)        sleep(0.0001)    # Write a command and argument    def write_cmd_arg(self, cmd, data):        self.bus.write_byte_data(self.addr, cmd, data)        sleep(0.0001)    # Write a block of data    def write_block_data(self, cmd, data):        self.bus.write_block_data(self.addr, cmd, data)        sleep(0.0001)    # Read a single byte    def read(self):        return self.bus.read_byte(self.addr)    # Read    def read_data(self, cmd):        return self.bus.read_byte_data(self.addr, cmd)    # Read a block of data    def read_block_data(self, cmd):        return self.bus.read_block_data(self.addr, cmd)