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。用户需要4位数密码，但当用户通过键盘输入数字时，液晶显示屏上没有显示任何内容。我希望当用户在lcd上输入数字*显示时。我只能设法在同一个地方获得*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()
LCD库
# -*- 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)
答案 0 :(得分：0)
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有效。如果没有，你必须重写它。
此外，*的数量应取决于外部计数器j，而不是i（我在评论中的错误，抱歉）：
mylcd.lcd_display_string((j+1) * "*", 2, 0)