树莓派4B（Ubuntu20.04）使用LCD1602液晶屏开机自动显示IP及其他信息

给树莓派4B装了Ubuntu20.04当做便携服务器在使用，为了便携，自然是不接网线使用WiFi，不接显示屏使用SSH远程连接工具，那就面临一个问题，在没有固定分配IP的情况下，怎么不通过接显示器获取IP用来远程连接呢？搜索看了下，最方便的应该就是开机自启自动显示IP等信息了。

• Ubuntu20.04 Python环境下，获取IP、磁盘存储占用等配置信息
  • 获取IP

  import socket
  def getIP():
  	ip = socket.gethostbyname(socket.gethostname())
  	return 'IP：'+ str(ip)
  

  • 获取MAC

  import uuid
  def getMAC():
  	node = uuid.getnode()
  	macHex = uuid.UUID(int=node).hex[-12:]
  	MAC = []
  	for i in range(len(macHex))[::2]:
  		MAC.append(macHex[i:i+2])
  	MAC =':'.join(MAC)
  	return 'MAC：' + str(MAC)
  

  • 获取磁盘占用

  import os
  def getDisk():
  	 disk = os.statvfs("/")
  	 disk_size = disk.f_bsize * disk.f_blocks / (1024 ** 3)  # 1G = 1024M  1M = 1024KB 1KB = 1024bytes
  	 sizeStr = str("%s" % format(disk_size, '.2f'))
  	 disk_used = disk.f_bsize * (disk.f_blocks - disk.f_bfree) / (1024 ** 3)
  	 usedStr = str("%s" % format(disk_used, '.2f'))
  	 return usedStr +  "/" + sizeStr
  

• 接入OLED屏幕，点亮屏幕显示
  • 接线参考开机自启动OLED屏显示
    GND：电源地（Ground）
    VCC：电源正（3.3V-5V）
    SCL：IIC时钟
    SDA：IIC数据
    连接树莓派：GND接Gound，VCC接5V，SCL接BCM3(SCL)，SDA接BCM2(SDA)。
    
    
  • 代码参考树莓派通过 I2C 驱动 LCD1602 液晶屏，在文件夹内写入驱动程序LCD1602.py

  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!')
  

  • 点亮显示

  #!/user/bin/env python 
  import smbus
  import datetime
  import time
  import pytz as pytz
  import sys
  import LCD1602 as LCD
  import os
  import socket
  import uuid
  def getIP():
  	ip = socket.gethostbyname(socket.gethostname())
  	return 'IP：'+ str(ip)
  def getMAC():
  	node = uuid.getnode()
  	macHex = uuid.UUID(int=node).hex[-12:]
  	MAC = []
  	for i in range(len(macHex))[::2]:
  		MAC.append(macHex[i:i+2])
  	MAC =':'.join(MAC)
  	return 'MAC：' + str(MAC)
  def getDisk():
  	 disk = os.statvfs("/")
  	 disk_size = disk.f_bsize * disk.f_blocks / (1024 ** 3)  # 1G = 1024M  1M = 1024KB 1KB = 1024bytes
  	 sizeStr = str("%s" % format(disk_size, '.2f'))
  	 disk_used = disk.f_bsize * (disk.f_blocks - disk.f_bfree) / (1024 ** 3)
  	 usedStr = str("%s" % format(disk_used, '.2f'))
  	 return usedStr +  "/" + sizeStr
  if __name__ == '__main__':  
      LCD.init_lcd()
      time.sleep(1)
      ipStr = getIP()
      LCD.print_lcd(0, 0, ipStr)
      for x in range(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:
          tz = pytz.timezone('Asia/Shanghai')  # 东八区
          show = getDisk() + " " + str(datetime.datetime.fromtimestamp(int(time.time()), tz).strftime('%H:%M'))
          LCD.print_lcd(0, 1, show )
          time.sleep(0.2)
  

• 设置开机自启动
  • 建立rc-local.service文件，如果存在的话可以不用创建
    sudo vim /etc/systemd/system/rc-local.service
  • 将下列内容复制进rc-local.service文件

    [Unit]
    Description=/etc/rc.local Compatibility
    ConditionPathExists=/etc/rc.local
    [Service]
    Type=forking
    ExecStart=/etc/rc.local start
    TimeoutSec=0
    StandardOutput=tty
    RemainAfterExit=yes
    SysVStartPriority=99
    [Install]
    WantedBy=multi-user.target
    

  • 创建文件rc.local
    sudo vim /etc/rc.local
  • 将下列内容复制进rc.local文件（对应脚本的位置和虚拟环境的位置自行修改）

    #!/bin/sh -e
    ##
    ## rc.local
    ##
    ## This script is executed at the end of each multiuser runlevel.
    ## Make sure that the script will "exit 0" on success or any other
    ## value on error.
    ##
    ## In order to enable or disable this script just change the execution
    ## bits.
    ##
    ## By default this script does nothing.
    # eaudio --start
    nohup /root/.virtualenvs/dj3/bin/python3 -u /opt/pi/getpi.py > test.out 2>&1 &
    

  • 给rc.local加上权限
    sudo chmod +x /etc/rc.local
  • 启用服务
    sudo systemctl enable rc-local
  • 启动服务并检查状态
    sudo systemctl start rc-local.service
sudo systemctl status rc-local.service
  • 重启系统测试
    reboot