脚本在我的字符 LCD 上显示 Unicode

Posted 2023-05-08

【中文标题】脚本在我的字符 LCD 上显示 Unicode

【英文标题】：Script is displaying Unicode onto my character LCD

【发布时间】：2018-06-15 12:10:42

【问题描述】：

我正在尝试让我的 Raspberry Pi 3 将从 MS SQL 数据库获取的信息显示到 2x16 字符 LCD 上。我有一个脚本，它从数据库中获取字符串，然后将其写入 .txt 和另一个读取 .txt 并将其显示在 LCD 上的脚本。但是，当它显示时，它是 Unicode 而不是“纯文本”。有没有办法转换它，以便 LCD 正确显示？

我无法插入图片，但它显示如下：(u'thewordineedhere',)

这是我用来获取字符串并写入 .txt 的脚本

import pymssql
conn = pymssql.connect(server='###.##.###.##',port='1433', user='User_Name', 
password='Password', database='Database_Name')
cursor = conn.cursor()
cursor.execute('Select Distinct * From Database_Name')
results = cursor.fetchall()
my_file = open("output.txt","w")
for string in results:
    print (string)
    my_file.write(str(string) +"\n")
my_file.close
conn.commit()
conn.close()

这是读取它并显示在 LCD 上的脚本。

import I2C_LCD_driver
from time import *

f = open('output.txt','r')
data = f.read()

mylcd = I2C_LCD_driver.lcd()
mylcd.lcd_display_string(data, 1)
mylcd.lcd_display_string("", 2)

如果需要，我也可以提供 I2C_LCD_driver.py、/etc/odbc.ini、/etc/odbcinst.ini 和 /etc/freetds/freetds.conf 脚本。

这里是 I2C_LCD_driver.py

# -*- coding: utf-8 -*-
# Original code found at:
# https://gist.github.com/DenisFromHR/cc863375a6e19dce359d

"""
Compiled, mashed and generally mutilated 2014-2015 by Denis Pleic
Made available under GNU GENERAL PUBLIC LICENSE

# Modified Python I2C library for Raspberry Pi
# as found on http://www.recantha.co.uk/blog/?p=4849
# Joined existing 'i2c_lib.py' and 'lcddriver.py' into a single library
# added bits and pieces from various sources
# By DenisFromHR (Denis Pleic)
# 2015-02-10, ver 0.1

"""

# i2c bus (0 -- original Pi, 1 -- Rev 2 Pi)
I2CBUS = 1

# LCD Address
ADDRESS = 0x3F

import smbus
from time import sleep

class i2c_device:
   def __init__(self, addr, port=I2CBUS):
      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)

# 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)


# 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

# flags for backlight control
LCD_BACKLIGHT = 0x08
LCD_NOBACKLIGHT = 0x00

En = 0b00000100 # Enable bit
Rw = 0b00000010 # Read/Write bit
Rs = 0b00000001 # Register select bit

    class lcd:
       #initializes objects and lcd
       def __init__(self):
      self.lcd_device = 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))

   # write a character to lcd (or character rom) 0x09: backlight | RS=DR<
   # works!
   def lcd_write_char(self, charvalue, mode=1):
      self.lcd_write_four_bits(mode | (charvalue & 0xF0))
      self.lcd_write_four_bits(mode | ((charvalue << 4) & 0xF0))


 # put string function with optional char positioning
   def lcd_display_string(self, string, line=1, pos=0):
    if line == 1:
      pos_new = pos
    elif line == 2:
      pos_new = 0x40 + pos
    elif line == 3:
      pos_new = 0x14 + pos
    elif line == 4:
      pos_new = 0x54 + pos

    self.lcd_write(0x80 + pos_new)

    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)

   # define backlight on/off (lcd.backlight(1); off= lcd.backlight(0)
   def backlight(self, state): # for state, 1 = on, 0 = off
      if state == 1:
         self.lcd_device.write_cmd(LCD_BACKLIGHT)
      elif state == 0:
         self.lcd_device.write_cmd(LCD_NOBACKLIGHT)

 # add custom characters (0 - 7)
   def lcd_load_custom_chars(self, fontdata):
      self.lcd_write(0x40);
      for char in fontdata:
         for line in char:
            self.lcd_write_char(line)         

【问题讨论】：

1) 好的，所以我用十六进制编辑器打开 output.txt 并没有看到 BOM。在那里查看时，我需要显示的所有文本仍然看起来像 (u'texthere',)。

16x2 LCD 如何显示 Unicode 文本？

【参考方案1】：

当从数据库中读取一行数据时，它会作为一个行对象返回，该对象可以访问各个列，就像它是一个列表一样。您看到的是行对象的字符串表示形式。你想要第一项，所以你需要使用string[0]。

我在 Windows 上的 VS2017 中使用 Python，我使用的是 pyodbc 而不是 pymssql：

import pyodbc

conn_str = (
    r"Driver=SQL Server Native Client 11.0;"
    r"Server=.\SQLEXPRESS;"
    r"Database=testing;"
    r"Trusted_Connection=yes;"
    )
conn = pyodbc.connect(conn_str)
cursor = conn.cursor()
cursor.execute('Select Distinct Name From Names')
results = cursor.fetchall()
conn.close()

my_file = open(r"C:\temp\output.txt","w")

for string in results:
    print (string[0])
    my_file.write(string[0] + "\n")

my_file.close()

请注意，我尽快关闭了数据库以保持清洁，我使用了文件的完整路径，并且必须使用带括号的 my_file.close() 才能使其正常工作。

【讨论】：

工作就像一个魅力！我唯一需要做的就是有： my_file.write(str(string[0]) + "\n")