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我有一个矩阵键盘和一个连接到树莓派的 hd44780 液晶显示器。

以下代码在python中。它需要用户输入 4 位密码,但是当用户通过键盘输入数字时,液晶显示屏上没有任何显示。我想当用户输入一个数字时会在液晶显示器上显示一个*。我只能设法在同一个地方得到 * 打印,但不能在 4 个单独的地方。

代码

import RPi.GPIO as GPIO
import time
import lcd
import os
import subprocess
from subprocess import call

mylcd = lcd.lcd()

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)

MATRIX = [['1', '2', '3', 'A'],
          ['4', '5', '6', 'B'],
          ['7', '8', '9', 'C'],
          ['*', '0', '#', 'D']]

ROW = [5,6,13,19] 
COL = [26,16,20,21] 

for j in range(4):
    GPIO.setup(COL[j], GPIO.OUT)
    GPIO.output(COL[j], 1)

for i in range(4):
    GPIO.setup(ROW[i], GPIO.IN, pull_up_down=GPIO.PUD_UP)

password = "1234"
attempt = ""
try:
    while (True):
        mylcd.lcd_display_string("Enter pw",1)
        for j in range(4):
            GPIO.output(COL[j], 0)

            for i in range(4):
                if GPIO.input(ROW[i]) == 0:
                    mylcd.lcd_display_string("*",2,0)
                    time.sleep(0.01)
                    while (GPIO.input(ROW[i]) == 0):
                        pass
                    attempt += MATRIX[i][j]
                    if len(attempt) == len(password):
                        if attempt == password:
                            mylcd.lcd_clear()
                            print "Password OK"
                            mylcd.lcd_display_string("Password",1 ,4 )
                            mylcd.lcd_display_string("Ok!",2 ,6 )
                            time.sleep(2)
                            mylcd.lcd_clear()
                            os.chdir('/home/pi/nfc/py532lib')
                            call('./nfc.sh')
                            mylcd.lcd_clear()
                        else:
                            print(attempt)
                            print "Password incorrect"
                            mylcd.lcd_display_string("Password",1,4)
                            mylcd.lcd_display_string("Incorrect!",2,3)
                            time.sleep(2)
                            mylcd.lcd_clear()
                            attempt = ""
            time.sleep(0.01)
            GPIO.output(COL[j], 1)
except KeyboardInterrupt:
    GPIO.cleanup()

液晶图书馆

# -*- 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 = 0

# LCD Address
ADDRESS = 0x27

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)


# 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)         
4

1 回答 1

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您的代码可能不正确。对于每个输出,您测试所有输入:

 for i in range(4):
     if GPIO.input(ROW[i]) == 0:

检查是否确实有一个正确的输入处于活动状态。如果没有,你必须重写它。

此外,数量*应该取决于外部计数器j,而不是i(我在评论中的错误,抱歉):

 mylcd.lcd_display_string((j+1) * "*", 2, 0)
于 2018-01-24T12:44:58.977 回答