1. Raspberry Pi 3
2. LCD Screen MT-20S4A 20x4 (Made in Russia). Based on HD44780.
3. Ralay switch RTD14005
4. DHT11 Humidity & Temperature Sensor

LCD Pin	Pin assignment	Raspberry Pi 2/3
1	GND	GND
2	+3V/5V	+5V
3	Uo	GPIO 23/Pin 16
4	Ao	GPIO 7/Pin 26
5	R/W	GND
6	E	GPIO 8/Pin 24
11	DB4	GPIO 24/Pin 18
12	DB5	GPIO 17/Pin 11
13	DB6	GPIO 27/Pin 14
14	DB7	GPIO 22/Pin 15
15	+LED	GPIO 18/ Pin 12
16	-LED	GND

• LCD Pin 7-10 not used.

Relay switch to NC (normal closed)

#!/usr/bin/env python

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(4, GPIO.OUT) # GPIO 4/ Pin 7 - Ralay.
GPIO.output(4, False)
GPIO.cleanup(4)

Relay switch to NO (normal open)

#!/usr/bin/env python

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)
GPIO.setup(4, GPIO.OUT) # GPIO 4/ Pin 7 - Ralay.
GPIO.output(4, True)

Brightness control

#!/usr/bin/env python

import time
import RPi.GPIO as GPIO

lcd_pin = 18
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(lcd_pin, GPIO.OUT)

current_time = time.strftime('%H')
br = GPIO.PWM(lcd_pin, 50)
br.start(0)

try:
    while True:
        if '07' < current_time < '17':
            br.ChangeDutyCycle(100)
        else:
            br.ChangeDutyCycle(50)
    time.sleep(900)
except KeyboardInterrput:
    pass

br.stop()
GPIO.cleanup(18)