为树莓派3B添加LCD1602液晶屏

Posted 2020-10-30 郑志强Aloha

树莓派3B针脚说明

 

LCD1602接线说明

VSS，接地
VDD，接5V电源
VO，液晶对比度调节，接电位器中间的引脚，电位器两边的引脚分别接5V和接地。
RS，寄存器选择，接GPIO14
RW，读写选择，接地，表示写模式
EN，使能信号，接GPIO15
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GPIO17
D5，数据位5，接GPIO18
D6，数据位6，接GPIO27
D7，数据位7，接GPIO22
A，液晶屏背光+，接5V
K，液晶屏背光-，接地

调整电位器

　　因为缺少1个5V的线，直接破皮拧一根进去就行，电位器调整到屏幕显示正常的对比度即可，第一次玩烙铁，焊的略丑…

lcd1602.py

#!/usr/bin/python   # # based on code from lrvick and LiquidCrystal # lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py # LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp #   from time import sleep   class lcd1602:   # 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   # 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       def __init__(self, pin_rs=14, pin_e=15, pins_db=[17, 18, 27, 22], GPIO = None): # Emulate the old behavior of using RPi.GPIO if we haven\'t been given # an explicit GPIO interface to use if not GPIO: import RPi.GPIO as GPIO self.GPIO = GPIO self.pin_rs = pin_rs self.pin_e = pin_e self.pins_db = pins_db   self.GPIO.setmode(GPIO.BCM) self.GPIO.setwarnings(False) self.GPIO.setup(self.pin_e, GPIO.OUT) self.GPIO.setup(self.pin_rs, GPIO.OUT)   for pin in self.pins_db: self.GPIO.setup(pin, GPIO.OUT)   self.write4bits(0x33) # initialization self.write4bits(0x32) # initialization self.write4bits(0x28) # 2 line 5x7 matrix self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor self.write4bits(0x06) # shift cursor right   self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF   self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS self.displayfunction |= self.LCD_2LINE   """ Initialize to default text direction (for romance languages) """ self.displaymode = self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) # set the entry mode   self.clear()     def begin(self, cols, lines):   if (lines > 1): self.numlines = lines self.displayfunction |= self.LCD_2LINE self.currline = 0     def home(self):   self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero self.delayMicroseconds(3000) # this command takes a long time!     def clear(self):   self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display self.delayMicroseconds(3000) # 3000 microsecond sleep, clearing the display takes a long time     def setCursor(self, col, row):   self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]   if ( row > self.numlines ): row = self.numlines - 1 # we count rows starting w/0   self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))     def noDisplay(self): """ Turn the display off (quickly) """   self.displaycontrol &= ~self.LCD_DISPLAYON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def display(self): """ Turn the display on (quickly) """   self.displaycontrol |= self.LCD_DISPLAYON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def noCursor(self): """ Turns the underline cursor on/off """   self.displaycontrol &= ~self.LCD_CURSORON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def cursor(self): """ Cursor On """   self.displaycontrol |= self.LCD_CURSORON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def noBlink(self): """ Turn on and off the blinking cursor """   self.displaycontrol &= ~self.LCD_BLINKON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def noBlink(self): """ Turn on and off the blinking cursor """   self.displaycontrol &= ~self.LCD_BLINKON self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)     def DisplayLeft(self): """ These commands scroll the display without changing the RAM """   self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)     def scrollDisplayRight(self): """ These commands scroll the display without changing the RAM """   self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);     def leftToRight(self): """ This is for text that flows Left to Right """   self.displaymode |= self.LCD_ENTRYLEFT self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);     def rightToLeft(self): """ This is for text that flows Right to Left """ self.displaymode &= ~self.LCD_ENTRYLEFT self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)     def autoscroll(self): """ This will \'right justify\' text from the cursor """   self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)     def noAutoscroll(self): """ This will \'left justify\' text from the cursor """   self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)     def write4bits(self, bits, char_mode=False): """ Send command to LCD """   self.delayMicroseconds(1000) # 1000 microsecond sleep   bits=bin(bits)[2:].zfill(8)   self.GPIO.output(self.pin_rs, char_mode)   for pin in self.pins_db: self.GPIO.output(pin, False)   for i in range(4): if bits[i] == "1": self.GPIO.output(self.pins_db[::-1][i], True)   self.pulseEnable()   for pin in self.pins_db: self.GPIO.output(pin, False)   for i in range(4,8): if bits[i] == "1": self.GPIO.output(self.pins_db[::-1][i-4], True)   self.pulseEnable()     def delayMicroseconds(self, microseconds): seconds = microseconds / float(1000000) # divide microseconds by 1 million for seconds sleep(seconds)     def pulseEnable(self): self.GPIO.output(self.pin_e, False) self.delayMicroseconds(1) # 1 microsecond pause - enable pulse must be > 450ns self.GPIO.output(self.pin_e, True) self.delayMicroseconds(1) # 1 microsecond pause - enable pulse must be > 450ns self.GPIO.output(self.pin_e, False) self.delayMicroseconds(1) # commands need > 37us to settle     def message(self, text): """ Send string to LCD. Newline wraps to second line"""   for char in text: if char == \'\\n\': self.write4bits(0xC0) # next line else: self.write4bits(ord(char),True)     if __name__ == \'__main__\':   lcd = lcd1602() lcd.clear() lcd.message("hello world!")

1602.py

#!/usr/bin/python   from lcd1602 import * from datetime import * import commands   def get_cpu_temp(): tmp = open(\'/sys/class/thermal/thermal_zone0/temp\') cpu = tmp.read() tmp.close() return \'{:.2f}\'.format( float(cpu)/1000 ) + \' C\'   def get_gpu_temp(): tmp = commands.getoutput(\'vcgencmd measure_temp|awk -F= \\\'{print $2}\\\'\').replace(\'\\\'C\',\'\') gpu = float(tmp) return \'{:.2f}\'.format( gpu ) + \' C\'   def get_time_now(): return datetime.now().strftime(\' %H:%M:%S\\n %Y-%m-%d\')   def get_ip_info(): return commands.getoutput(\'ifconfig wlan0|grep inet|awk -Faddr: \\\'{print $2}\\\'|awk \\\'{print $1}\\\'\')   def get_mem_info(): total= commands.getoutput(\'free -m|grep Mem:|awk \\\'{print $2}\\\'\') free = commands.getoutput(\'free -m|grep cache:|awk \\\'{print $4}\\\'\') return \'MEM:\\n \' + free +\' / \'+ total +\' M\'   lcd = lcd1602() lcd.clear()   if __name__ == \'__main__\':   while(1): lcd.clear() lcd.message( get_ip_info() ) sleep(5)   lcd.clear() lcd.message( get_time_now() ) sleep(5)   lcd.clear() lcd.message( get_mem_info() ) sleep(5)   lcd.clear() lcd.message( \'CPU: \' + get_cpu_temp()+\'\\n\' ) lcd.message( \'GPU: \' + get_gpu_temp() ) sleep(5)

　　将以上两个文件保存在同一个目录下，运行1602.py即可打印信息到LCD上。

效果图

参考链接

http://www.cnblogs.com/xiaowuyi/p/4051238.html
https://www.6zou.net/tech/raspberry-pi-lcd1602-system-monitor.html