硬件准备

需要以下硬件：

• 树莓派
• 面包板
• 1602液晶屏一块
• 10K电位器
• 杜邦线
• 排针
• 面包板电源

1602 LCD液晶屏

LCD1602液晶屏提供了16列x2行的ASCII字符显示能力，工作电压5V，提供4位数据与8位数据两种工作模式，因为Raspberry Pi的GPIO口数量很有限，所以使用4位数据模式。LCD1602液晶屏模块提供了16个引脚，我们只需接其中的12个即可–请参考GPIO命名规则：

• VSS，接地，RPi PIN 6
• VDD，接5V电源，PRi PIN 2
• VO，液晶对比度调节，接电位器中间的引脚
• RS，寄存器选择，接GPIO 14，RPi PIN 8
• RW，读写选择，接地，表示写模式，PRi PIN 6
• EN，使能信号，接GPIO 15，RPi PIN 10
• D0，数据位0，4位工作模式下不用，不接
• D1，数据位1，4位工作模式下不用，不接
• D2，数据位2，4位工作模式下不用，不接
• D3，数据位3，4位工作模式下不用，不接
• D4，数据位4，接GPIO 17，RPi PIN 11
• D5，数据位5，接GPIO 18，RPi PIN 12
• D6，数据位6，接GPIO 27，RPi PIN 13
• D7，数据位7，接GPIO 22，RPi PIN 15
• A，液晶屏背光+，接5V，RPi PIN 2
• K，液晶屏背光-，接地，RPi PIN 6

注意事项

• 电源VDD最后接上
• 排针焊接在液晶屏时注意不要虚焊，也可以用万用表测量一下
• RW脚注意一定要接地
• 调节电位器可以调节液晶对比度

代码

1. #!/usr/bin/python
3. #
4. # based on code from lrvick and LiquidCrystal
5. # lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py
6. # LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp
7. #
9. from time import sleep
10. from datetime import datetime
11. from time import sleep
13. class Adafruit_CharLCD:
15. # commands
16. LCD_CLEARDISPLAY = 0x01
17. LCD_RETURNHOME = 0x02
18. LCD_ENTRYMODESET = 0x04
19. LCD_DISPLAYCONTROL = 0x08
20. LCD_CURSORSHIFT = 0x10
21. LCD_FUNCTIONSET = 0x20
22. LCD_SETCGRAMADDR = 0x40
23. LCD_SETDDRAMADDR = 0x80
25. # flags for display entry mode
26. LCD_ENTRYRIGHT = 0x00
27. LCD_ENTRYLEFT = 0x02
28. LCD_ENTRYSHIFTINCREMENT = 0x01
29. LCD_ENTRYSHIFTDECREMENT = 0x00
31. # flags for display on/off control
32. LCD_DISPLAYON = 0x04
33. LCD_DISPLAYOFF = 0x00
34. LCD_CURSORON = 0x02
35. LCD_CURSOROFF = 0x00
36. LCD_BLINKON = 0x01
37. LCD_BLINKOFF = 0x00
39. # flags for display/cursor shift
40. LCD_DISPLAYMOVE = 0x08
41. LCD_CURSORMOVE = 0x00
43. # flags for display/cursor shift
44. LCD_DISPLAYMOVE = 0x08
45. LCD_CURSORMOVE = 0x00
46. LCD_MOVERIGHT = 0x04
47. LCD_MOVELEFT = 0x00
49. # flags for function set
50. LCD_8BITMODE = 0x10
51. LCD_4BITMODE = 0x00
52. LCD_2LINE = 0x08
53. LCD_1LINE = 0x00
54. LCD_5x10DOTS = 0x04
55. LCD_5x8DOTS = 0x00
59. def __init__(self, pin_rs=8, pin_e=10, pins_db=[11,12,13,15], GPIO = None):
60. # Emulate the old behavior of using RPi.GPIO if we haven't been given
61. # an explicit GPIO interface to use
62. if not GPIO:
63. import RPi.GPIO as GPIO
64. GPIO.setwarnings(False)
66. self.GPIO = GPIO
67. self.pin_rs = pin_rs
68. self.pin_e = pin_e
69. self.pins_db = pins_db
71. self.GPIO.setmode(GPIO.BOARD)
72. self.GPIO.setup(self.pin_e, GPIO.OUT)
73. self.GPIO.setup(self.pin_rs, GPIO.OUT)
75. for pin in self.pins_db:
76. self.GPIO.setup(pin, GPIO.OUT)
78. self.write4bits(0x33) # initialization
79. self.write4bits(0x32) # initialization
80. self.write4bits(0x28) # 2 line 5x7 matrix
81. self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor
82. self.write4bits(0x06) # shift cursor right
84. self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF
86. self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
87. self.displayfunction |= self.LCD_2LINE
89. """ Initialize to default text direction (for romance languages) """
90. self.displaymode = self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
91. self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) # set the entry mode
93. self.clear()
96. def begin(self, cols, lines):
98. if (lines > 1):
99. self.numlines = lines
100. self.displayfunction |= self.LCD_2LINE
101. self.currline = 0
104. def home(self):
106. self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero
107. self.delayMicroseconds(3000) # this command takes a long time!
110. def clear(self):
112. self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display
113. self.delayMicroseconds(3000) # 3000 microsecond sleep, clearing the display takes a long time
116. def setCursor(self, col, row):
118. self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]
120. if ( row > self.numlines ):
121. row = self.numlines - 1 # we count rows starting w/0
123. self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))
126. def noDisplay(self):
127. """ Turn the display off (quickly) """
129. self.displaycontrol &= ~self.LCD_DISPLAYON
130. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
133. def display(self):
134. """ Turn the display on (quickly) """
136. self.displaycontrol |= self.LCD_DISPLAYON
137. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
140. def noCursor(self):
141. """ Turns the underline cursor on/off """
143. self.displaycontrol &= ~self.LCD_CURSORON
144. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
147. def cursor(self):
148. """ Cursor On """
150. self.displaycontrol |= self.LCD_CURSORON
151. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
154. def noBlink(self):
155. """ Turn on and off the blinking cursor """
157. self.displaycontrol &= ~self.LCD_BLINKON
158. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
161. def noBlink(self):
162. """ Turn on and off the blinking cursor """
164. self.displaycontrol &= ~self.LCD_BLINKON
165. self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
168. def DisplayLeft(self):
169. """ These commands scroll the display without changing the RAM """
171. self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)
174. def scrollDisplayRight(self):
175. """ These commands scroll the display without changing the RAM """
177. self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);
180. def leftToRight(self):
181. """ This is for text that flows Left to Right """
183. self.displaymode |= self.LCD_ENTRYLEFT
184. self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);
187. def rightToLeft(self):
188. """ This is for text that flows Right to Left """
189. self.displaymode &= ~self.LCD_ENTRYLEFT
190. self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
193. def autoscroll(self):
194. """ This will 'right justify' text from the cursor """
196. self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
197. self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
200. def noAutoscroll(self):
201. """ This will 'left justify' text from the cursor """
203. self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
204. self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
207. def write4bits(self, bits, char_mode=False):
208. """ Send command to LCD """
210. self.delayMicroseconds(1000) # 1000 microsecond sleep
212. bits=bin(bits)[2:].zfill(8)
214. self.GPIO.output(self.pin_rs, char_mode)
216. for pin in self.pins_db:
217. self.GPIO.output(pin, False)
219. for i in range(4):
220. if bits[i] == "1":
221. self.GPIO.output(self.pins_db[::-1][i], True)
223. self.pulseEnable()
225. for pin in self.pins_db:
226. self.GPIO.output(pin, False)
228. for i in range(4,8):
229. if bits[i] == "1":
230. self.GPIO.output(self.pins_db[::-1][i-4], True)
232. self.pulseEnable()
235. def delayMicroseconds(self, microseconds):
236. seconds = microseconds / float(1000000) # divide microseconds by 1 million for seconds
237. sleep(seconds)
240. def pulseEnable(self):
241. self.GPIO.output(self.pin_e, False)
242. self.delayMicroseconds(1) # 1 microsecond pause - enable pulse must be > 450ns
243. self.GPIO.output(self.pin_e, True)
244. self.delayMicroseconds(1) # 1 microsecond pause - enable pulse must be > 450ns
245. self.GPIO.output(self.pin_e, False)
246. self.delayMicroseconds(1) # commands need > 37us to settle
249. def message(self, text):
250. """ Send string to LCD. Newline wraps to second line"""
252. for char in text:
253. if char == '\n':
254. self.write4bits(0xC0) # next line
255. else:
256. self.write4bits(ord(char),True)
259. if __name__ == '__main__':
261. lcd = Adafruit_CharLCD()
262. lcd.noBlink()
264. while True:
265. sleep(1)
266. lcd.clear()
267. lcd.message(datetime.now().strftime(' %I : %M : %S \n%a %b %d %Y'))

完成后效果

未经允许不得转载：网购经验网 » 在1602液晶屏上显示当前时间–电子钟