Display CPU Temperature and IP Address for Raspberry Pi

I wanted to use the LCD1602 display screen to show my IP address and CPU temperature whilst I was using the Raspberry Pi so I did not end up frying it. The LCD screen displays only two lines of characters in 16 columns as such, due to the limits, I chose to only display the text "CPU: " and "IP: " with the corresponding data.

The display uses the I2C interface to connect the serial-input and parallel-output module to the screen which allows only 4 wires to be needed to operate the LCD.

The serial-to-parallel IC chip is PCF8574T with default I2C address (0x27) which you will see referenced in the code.

You will nee a breadboard, RGB led, wires, resistors, LCD, and the raspberry Pi.

Step 1: Wire Up the LCD

Attach the wires from the LCD to the the correct GPIO pins on the Pi:

• GND to Pi GND
• 5V to Pi 5V
• SDA to Pi SDA1
• SCL to Pi SCL1

Step 2: Write the Python Code to Run Your Message on Your LCD Display

from PCF8574 import PCF8574_GPIO

from Adafruit_LCD1602 import Adafruit_CharLCD

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 loop():

mcp.output(3,1)

lcd.begin(16,2)

while(True):

lcd.setCursor(0,0)
lcd.message( 'CPU: ' + get_cpu_temp()+'\n' )

PCF8574_address = 0x27

mcp = PCF8574_GPIO(PCF8574_address)

lcd = Adafruit_CharLCD(pin_rs=0, pin_e=2, pins_db=[4,5,6,7], GPIO=mcp)

if __name__ == '__main__':

try:

loop()

except KeyboardInterrupt: destroy()

Test the LCD screen works.

If there is no messaging then turn the dial on the back of the LCD board until you can see the text.

Step 3: Hook Up the RGB Light to the Pi

Hook the RGB up to the required pins and use the resistors to control the flow.
GPIO17
GPIO27
3V3 - longer pin
GPIO18

Step 4: Write the Python Code to Set the Color to Your RGB Led

from PCF8574 import PCF8574_GPIO from Adafruit_LCD1602 import Adafruit_CharLCD

from time import sleep, strftime from datetime import datetime

import subprocess

import RPi.GPIO as GPIO import time import random

pins = [15, 11, 13]

def setup2():
global pwmRed,
pwmGreen,
pwmBlue
GPIO.setmode(GPIO.BOARD)
GPIO.setup(pins, GPIO.OUT)
GPIO.output(pins, GPIO.HIGH)
pwmRed = GPIO.PWM(pins[0], 2000)
pwmGreen = GPIO.PWM(pins[1], 2000)
pwmBlue = GPIO.PWM(pins[2], 2000)
pwmRed.start(0)
pwmGreen.start(0)
pwmBlue.start(0)

def setColor(r_val,g_val,b_val):
pwmRed.ChangeDutyCycle(r_val)
pwmGreen.ChangeDutyCycle(g_val)
pwmBlue.ChangeDutyCycle(b_val)

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_cpu_temp2():
tmp = open('/sys/class/thermal/thermal_zone0/temp')
cpu2 = tmp.read()
tmp.close()
return cpu2

def get_time_now():
return datetime.now().strftime(' %H:%M:%S')

def get_IP():
IP = subprocess.check_output(["hostname", "-I"]).split()[0]
IP2 = 'IP' + str(IP)
IP3 = (IP2[4:-1])
return IP3

def loop():
mcp.output(3,1)
lcd.begin(16,2)
while(True):
lcd.setCursor(0,0)
lcd.message( 'CPU: ' + get_cpu_temp()+'\n' )
lcd.message('IP: ' + get_IP())
if int(get_cpu_temp2()) > 55500:
r=(62) g=(75) b=(100)
setColor(r,g,b)
print(get_cpu_temp2())
elif int(get_cpu_temp2()) < 55400 and int(get_cpu_temp2()) < 54000: r=(10)
setColor(r,g,b) print(get_cpu_temp2()) else: r=(10)
setColor(r,g,b) print(get_cpu_temp2()) sleep(1)

def destroy():
lcd.clear()
PCF8574_address = 0x27
PCF8574A_address = 0x3F
try: mcp = PCF8574_GPIO(PCF8574_address)
except:
try: mcp = PCF8574_GPIO(PCF8574A_address)
except:
print ('I2C Address Error !')
exit(1)
lcd = Adafruit_CharLCD(pin_rs=0, pin_e=2, pins_db=[4,5,6,7], GPIO=mcp)

if __name__ == '__main__':
setup2()
print ('Program is starting ... ')
try:
loop()
except KeyboardInterrupt:
destroy()

Step 5: Enjoy

Run the code, your light will now change colours based on the CPU temperature. Enjoy!