raspberry pi LCD 1602 I2C display script

I2CLCD1602.py

#!/usr/bin/env python3
########################################################################
# Filename    : I2CLCD1602.py
# Description : Use the LCD display data
# Author      : freenove
# modification: 2023/05/15
########################################################################
import time
from time import sleep, strftime
import smbus
import subprocess
from datetime import datetime
import psutil
import os

# library class - do not change

class CharLCD1602(object):
    def __init__(self):
        # Note you need to change the bus number to 0 if running on a revision 1 Raspberry Pi.
        self.bus = smbus.SMBus(1)
        self.BLEN = 1  # turn on/off background light
        self.PCF8574_address = 0x27  # I2C address of the PCF8574 chip.
        self.PCF8574A_address = 0x3f  # I2C address of the PCF8574A chip.
        self.LCD_ADDR =self.PCF8574_address  
    def write_word(self,addr, data):
        temp = data
        if self.BLEN == 1:
            temp |= 0x08
        else:
            temp &= 0xF7
        self.bus.write_byte(addr ,temp)

    def send_command(self,comm):
        # Send bit7-4 firstly
        buf = comm & 0xF0
        buf |= 0x04               # RS = 0, RW = 0, EN = 1
        self.write_word(self.LCD_ADDR ,buf)
        time.sleep(0.002)
        buf &= 0xFB               # Make EN = 0
        self.write_word(self.LCD_ADDR ,buf)
        # Send bit3-0 secondly
        buf = (comm & 0x0F) << 4
        buf |= 0x04               # RS = 0, RW = 0, EN = 1
        self.write_word(self.LCD_ADDR ,buf)
        time.sleep(0.002)
        buf &= 0xFB               # Make EN = 0
        self.write_word(self.LCD_ADDR ,buf)

    def send_data(self,data):
        # Send bit7-4 firstly
        buf = data & 0xF0
        buf |= 0x05               # RS = 1, RW = 0, EN = 1
        self.write_word(self.LCD_ADDR ,buf)
        time.sleep(0.002)
        buf &= 0xFB               # Make EN = 0
        self.write_word(self.LCD_ADDR ,buf)
        # Send bit3-0 secondly
        buf = (data & 0x0F) << 4
        buf |= 0x05               # RS = 1, RW = 0, EN = 1
        self.write_word(self.LCD_ADDR ,buf)
        time.sleep(0.002)
        buf &= 0xFB               # Make EN = 0
        self.write_word(self.LCD_ADDR ,buf)

    def i2c_scan(self):
        cmd = "i2cdetect -y 1 |awk \'NR>1 {$1=\"\";print}\'"
        result = subprocess.check_output(cmd, shell=True).decode()
        result = result.replace("\n", "").replace(" --", "")
        i2c_list = result.split(' ')
        return i2c_list

    def init_lcd(self,addr=None, bl=1):
        i2c_list = self.i2c_scan()
#         print(f"i2c_list: {i2c_list}")
        if addr is None:
            if '27' in i2c_list:
                self.LCD_ADDR = self.PCF8574_address
            elif '3f' in i2c_list:
                self.LCD_ADDR = self.PCF8574A_address
            else:
                raise IOError("I2C address 0x27 or 0x3f no found.")
        else:
            self.LCD_ADDR = addr
            if str(hex(addr)).strip('0x') not in i2c_list:
                raise IOError(f"I2C address {str(hex(addr))} or 0x3f no found.")    
        self.BLEN = bl
        try:
            self.send_command(0x33) # Must initialize to 8-line mode at first
            time.sleep(0.005)
            self.send_command(0x32) # Then initialize to 4-line mode
            time.sleep(0.005)
            self.send_command(0x28) # 2 Lines & 5*7 dots
            time.sleep(0.005)
            self.send_command(0x0C) # Enable display without cursor
            time.sleep(0.005)
            self.send_command(0x01) # Clear Screen
            self.buswrite_byte(self.LCD_ADDR, 0x08)
        except:
            return False
        else:
            return True

    def clear(self):
        self.send_command(0x01) # Clear Screen

    def openlight(self):  # Enable the backlight
        self.bus.write_byte(0x27,0x08)
        self.bus.close()

    def write(self,x, y, str):
        if x < 0:
            x = 0
        if x > 15:
            x = 15
        if y <0:
            y = 0
        if y > 1:
            y = 1
        # Move cursor
        addr = 0x80 + 0x40 * y + x
        self.send_command(addr)
        for chr in str:
            self.send_data(ord(chr))
    def display_num(self,x, y, num):
        addr = 0x80 + 0x40 * y + x
        self.send_command(addr)
        self.send_data(num)
    



#!/usr/bin/env python3
########################################################################
# Filename    : I2CLCD1602.py
# Description : Use the LCD display data
# Author      : freenove, @donrestarone
# modification: 2023/05/15
########################################################################

lcd1602 = CharLCD1602()

# write custom code here

def get_cpu_temp():     # get CPU temperature from file "/sys/class/thermal/thermal_zone0/temp"
    tmp = open('/sys/class/thermal/thermal_zone0/temp')
    cpu = tmp.read()
    tmp.close()
    return '{:.2f}'.format( float(cpu)/1000 ) + ' C '

def get_uptime():     
    uptime = os.popen('uptime -p').read()[:-1]
    return uptime

def get_cpu_usage():     
    usage = str(psutil.cpu_percent())
    return usage

def get_memory_usage():     
    usage = str(round(psutil.virtual_memory().available * 100 / psutil.virtual_memory().total, 2))
    return usage

def get_storage():     
    hdd = psutil.disk_usage('/')
    return '{:.2f}'.format( hdd.percent ) + ' % '
 
def get_time_now():     # get system time
    return datetime.now().strftime("%-I:%-M %p")

def get_current_date():
    return datetime.now().strftime("%a %b %-d %Y")
    
def loop():
    lcd1602.init_lcd()
    count = 0
    while(True):
        # alternate between greeting and dynamic info
        lcd1602.clear()
        lcd1602.write(0, 0, 'Hello World!' )# display greeting
        lcd1602.write(0, 1, get_uptime())   # display the counter
        time.sleep(1)
        lcd1602.clear()
        lcd1602.write(0, 0, 'Storage' )
        lcd1602.write(0, 1, get_storage() + ' used' )  
        time.sleep(1)
        lcd1602.clear()
        lcd1602.write(0, 0, 'CPU' )
        lcd1602.write(0, 1, get_cpu_usage() + '% ' + 'used' )  
        time.sleep(1)
        lcd1602.clear()
        lcd1602.write(0, 0, 'Memory' )
        lcd1602.write(0, 1, get_memory_usage() + '% ' + 'free' )  
        time.sleep(1)
        lcd1602.clear()
        lcd1602.write(0, 0, 'CPU Temperature')# display CPU temperature
        lcd1602.write(0, 1, get_cpu_temp() )  
        time.sleep(1)
        lcd1602.clear()
        lcd1602.write(0, 0, get_current_date())
        lcd1602.write(0, 1, get_time_now() )  
        time.sleep(1)
        lcd1602.clear()
        count += 1
def destroy():
    lcd1602.clear()
if __name__ == '__main__':
    print ('Program is starting ... ')
    try:
        loop()
    except KeyboardInterrupt:
        destroy()
    

code above adopted by combining the LCD display class and custom display script here: https://github.com/Freenove/Freenove_Complete_Starter_Kit_for_Raspberry_Pi/tree/main/Code/Python_GPIOZero_Code/20.1.1_I2CLCD1602

readme

first start

• ensure tmux is installed
• ensure I2C & SPI are enabled by entering raspi config: sudo raspi-config
• at the ~ level create bash script named display.sh (dont forget to chmod +x display.sh to make it executable) that starts tmux and kicks off the python display service (display.py)
• at the ~ level copy paste the python source above to the python script display.py
• ensure the service file display.service exists at /etc/systemd/system/display.service
• enable the display.service by running: sudo systemctl start display.service && sudo systemctl enable display.service

display.sh

#!/bin/bash
sessname="display"


# Create a new session named "$sessname", and run command
tmux new-session -d -s "$sessname"
tmux send-keys -t "$sessname" "python3 display.py" Enter

# Attach to session named "$sessname"
#tmux attach -t "$sessname"

display.py

see here: https://gist.github.com/donrestarone/812dcd467b0df8af6a13f398156c3a3b#file-i2clcd1602-py

display.service

[Unit]
Description=Display service
After=network.target

[Service]
WorkingDirectory=/home/donrestarone
ExecStart=/bin/bash /home/donrestarone/display.sh
Type=forking
User=donrestarone
[Install]
WantedBy=multi-user.target

• dont forget to start and enable it! sudo systemctl start display.service && sudo systemctl enable display.service