1602A screen , remember to adjust the potentiometer
LCD1602 wiring instructions
VSS, ground
VDD, connect 5V power supply
VO, LCD contrast adjustment, connect the pin in the middle of the potentiometer, the pins on both sides of the potentiometer are connected to 5V and ground respectively.
RS, register selection, connected to GPIO14
RW, read and write selection, grounded, indicating write mode
EN, enable signal, connected to GPIO15
D0, data bit 0, not used in 4-bit working mode, not connected to
D1, data bit 1, 4-bit work Not used in mode, not connected to
D2, data bit 2, not used in 4-bit working mode, not connected to
D3, data bit 3, not used in 4-bit working mode, not connected to
D4, data bit 4, connected to GPIO17
D5, data bit 5, Connect GPIO18
D6, data bit 6, connect GPIO27
D7, data bit 7, connect GPIO22
A, LCD backlight +, connect 5V
K, LCD backlight -, ground There are two files in
total ,
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)
Save the above two files in the same directory and run 1602.py to print the information on the LCD.
Check out the code for yourself