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在2x16字符的LCD上。我有一个脚本从数据库中获取字符串然后将其写入.txt，另一个脚本读取.txt并将其显示在LCD上。但是，当它显示时，它是用Unicode而不是“纯文本”。有没有办法转换这个，所以液晶显示器将正确显示？
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()
这是读取它并在液晶显示屏上显示的脚本。
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)
如有必要，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)
答案 0 :(得分：1)
当从数据库中读取一行数据时，它将作为行对象返回，该行对象可以访问各个列，就好像它是一个列表一样。您所看到的是行对象的字符串表示形式。您需要第一个项目，因此需要使用string[0]。
我在Windows上使用VS2017中的Python，我使用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，我尽快关闭数据库以保持清洁，我使用了文件的完整路径，并且我必须使用括号的my_file.close()来使其工作。