1. 1602a LCD屏
- 接线端子表：
| 序号 | LCD屏 16PIN | 树莓派 40PIN 物理序号 | 备注 |
|---|---|---|---|
| 1 | VSS | 06 | GND |
| 2 | VDD | 02 | 5V |
| 3 | V0 | 电位器 | 对比度，0-5V |
| 4 | RS | 08 | GPIO-14 |
| 5 | RW | 06 | 写模式：接地 |
| 6 | EN | 10 | GPIO-15 |
| 7 | D0 | - | |
| 8 | D1 | - | |
| 9 | D2 | - | |
| 10 | D3 | - | |
| 11 | D4 | 11 | GPIO-17 |
| 12 | D5 | 12 | GPIO-18 |
| 13 | D6 | 13 | GPIO-27 |
| 14 | D7 | 15 | GPIO-22 |
| 15 | A | 串约500Ω电阻后接02 | 背光正 |
| 16 | K | 06 | 背光负 |
- 接线图
raspi-lcd1602a.png
2. 代码
- 目录如下，就两个文件：
.
├───LCD1602a
│ ├───1602.py # 主程序，可显示时间、CPU、RAM的使用情况
│ └───lcd1602.py # 配置程序
│...
lcd1602.py
# 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
import time
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):
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.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
time.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(" LCD 1602 Test \n123456789ABCDEF")
1602.py
import os
import time
from lcd1602 import *
from datetime import datetime
# run command
def run_cmd(cmd):
p = os.popen(cmd).readline().strip().split()
return p
def now():
return datetime.now().strftime('%Y-%m-%d %a \n%H:%M:%S')
def cpu():
cpu_temp = run_cmd('vcgencmd measure_temp')
cpu_info = run_cmd("top -bn1 | awk '/Cpu\(s\)/'")
cpu_usage = 1 - float(cpu_info[7])/100.0
status = 'CPU Temp: {}\n'.format(cpu_temp[0].replace("temp=", ""))
status += ' Used: {:.2%}'.format(cpu_usage)
return status
def ram():
ram_info = run_cmd("free -m | awk '/Mem/'")
ram_usage = (int(ram_info[1]) - int(ram_info[6])) / float(ram_info[1])
status = 'RAM Totl: {}M\n'.format(ram_info[1])
status += ' Used: {:.2%}'.format(ram_usage)
return status
def ip():
ip = run_cmd("sudo ifconfig wlan0 | awk '/inet/'")
return 'IP Addr: \n {}'.format(ip[1])
print(now(), cpu(), ram(), ip(), sep='\n')
lcd = lcd1602()
lcd.clear()
while(1):
lcd.clear()
lcd.message(now())
time.sleep(10)
lcd.clear()
lcd.message(cpu())
time.sleep(10)
lcd.clear()
lcd.message(ram())
time.sleep(10)