树莓派通过 I2C 驱动 LCD1602 液晶屏

前一阵用废旧的树莓派做了一个NAS服务器，手里还要一块闲置的LCD 1602 液晶屏模块，可以用来实时显示IP，作为NAS的服务器输出显示。

在树莓派上LCD 1602 液晶屏模块的使用非常简单，可以用 I2C 方式的驱动，只要使能0，5V，tx,tf四根线就可实现使能，屏幕上自带调压电阻可以调整亮度对比度。极大的简化LED接线和驱动使用。带 I2C 模块的 1602 屏幕背面如图所示。

第一步，线序超级简单，不要接错了。

GND — GND
VCC — 接树莓派 5V
SDA — I2C 数据
SCL — I2C 时钟

第二步，启用树莓派的I2C功能。

sudo apt-get install -y python-smbus
sudo apt-get install -y i2c-tools

第三步，使能I2C
sudo raspi-config
选择I2C

第四步，用 Python 控制 LCD1602 显示需要的信息。

平时用来显示时间的程序代码例 测试程序test.py：

import smbus
import time
import sys
import LCD1602 as LCD
 
if __name__ == '__main__':  
    LCD.init_lcd()
    time.sleep(1)
    LCD.print_lcd(2, 0, '测试程序test')
    for x in xrange(1, 4):
        LCD.turn_light(0)
        LCD.print_lcd(4, 1, 'LIGHT OFF')
        time.sleep(0.5)
        LCD.turn_light(1)
        LCD.print_lcd(4, 1, 'LIGHT ON ')
        time.sleep(0.5)
 
    LCD.turn_light(0)
     
    while True:
        now = time.strftime('%m/%d %H:%M:%S', time.localtime(time.time()))
        LCD.print_lcd(1, 1, now)
        time.sleep(0.2)

注意1，LCD1602模块不显示可以调整一下电阻，亮度太高也不行的。
注意2，LCD1602驱动在程序里作为一个python导入模块使用。找不到的，用我下面共享的，保存为LCD1602.py作为驱动和程序放在同目录即可。怎么样开机自动运行参考我的另一篇文章：树莓派Python程序开机自启动（Linux下Python程序开机自启动）

LCD1602.py驱动程序代码

import time
import smbus
BUS = smbus.SMBus(1)
LCD_ADDR = 0x27
BLEN = 1 #turn on/off background light
 
def turn_light(key):
    global BLEN
    BLEN = key
    if key ==1 :
        BUS.write_byte(LCD_ADDR ,0x08)
    else:
        BUS.write_byte(LCD_ADDR ,0x00)
 
def write_word(addr, data):
    global BLEN
    temp = data
    if BLEN == 1:
        temp |= 0x08
    else:
        temp &= 0xF7
    BUS.write_byte(addr ,temp)
 
def send_command(comm):
    # Send bit7-4 firstly
    buf = comm & 0xF0
    buf |= 0x04               # RS = 0, RW = 0, EN = 1
    write_word(LCD_ADDR ,buf)
    time.sleep(0.002)
    buf &= 0xFB               # Make EN = 0
    write_word(LCD_ADDR ,buf)
     
    # Send bit3-0 secondly
    buf = (comm & 0x0F) << 4
    buf |= 0x04               # RS = 0, RW = 0, EN = 1
    write_word(LCD_ADDR ,buf)
    time.sleep(0.002)
    buf &= 0xFB               # Make EN = 0
    write_word(LCD_ADDR ,buf)
 
def send_data(data):
    # Send bit7-4 firstly
    buf = data & 0xF0
    buf |= 0x05               # RS = 1, RW = 0, EN = 1
    write_word(LCD_ADDR ,buf)
    time.sleep(0.002)
    buf &= 0xFB               # Make EN = 0
    write_word(LCD_ADDR ,buf)
     
    # Send bit3-0 secondly
    buf = (data & 0x0F) << 4
    buf |= 0x05               # RS = 1, RW = 0, EN = 1
    write_word(LCD_ADDR ,buf)
    time.sleep(0.002)
    buf &= 0xFB               # Make EN = 0
    write_word(LCD_ADDR ,buf)
 
def init_lcd():
    try:
        send_command(0x33) # Must initialize to 8-line mode at first
        time.sleep(0.005)
        send_command(0x32) # Then initialize to 4-line mode
        time.sleep(0.005)
        send_command(0x28) # 2 Lines & 5*7 dots
        time.sleep(0.005)
        send_command(0x0C) # Enable display without cursor
        time.sleep(0.005)
        send_command(0x01) # Clear Screen
        BUS.write_byte(LCD_ADDR ,0x08)
    except:
        return False
    else:
        return True
 
def clear_lcd():
    send_command(0x01) # Clear Screen
 
def print_lcd(x, y, str):
    if x < 0:
        x = 0
    if x > 15:
        x = 15
    if y <0:
        y = 0
    if y > 1:
        y = 1
 
    # Move cursor
    addr = 0x80 + 0x40 * y + x
    send_command(addr)
     
    for chr in str:
        send_data(ord(chr))
 
if __name__ == '__main__':
    init_lcd()
    print_lcd(0, 0, 'Hello, world!')```