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I have an LCD display that has a backlight (since when I plug it in it lights up). However, using the code below I cant get it to turn on. Any help would be greatly appreciated

import smbus
import time

# Set up I2C LCD
I2C_ADDR = 0x27  # I2C address of the LCD module
LCD_WIDTH = 16   # Maximum characters per line

LCD_CHR = 1  # Mode - Sending data
LCD_CMD = 0  # Mode - Sending command

LCD_LINE_1 = 0x80  # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0  # LCD RAM address for the 2nd line

ENABLE = 0b00000100  # Enable bit
BACKLIGHT_ON = 0x08  # Backlight on command
BACKLIGHT_OFF = 0x00  # Backlight off command

# Timing constants
E_PULSE = 0.0005
E_DELAY = 0.0005

bus = smbus.SMBus(1)  # Rev 2 Pi uses 1

def lcd_init():
    # Initialize display
    lcd_byte(0x33, LCD_CMD)
    lcd_byte(0x32, LCD_CMD)
    lcd_byte(0x06, LCD_CMD)
    lcd_byte(0x0C, LCD_CMD)
    lcd_byte(0x28, LCD_CMD)
    lcd_byte(0x01, LCD_CMD)
    time.sleep(E_DELAY)
    
    # turn on backlight
    bus.write_byte(I2C_ADDR,BACKLIGHT_ON)
    

    


def lcd_byte(bits, mode):
    # Send byte to data pins
    # bits = data
    # mode = 1 for data, 0 for command

    bits_high = mode | (bits & 0xF0) | ENABLE
    bits_low = mode | ((bits << 4) & 0xF0) | ENABLE

    # High bits
    bus.write_byte(I2C_ADDR, bits_high)
    lcd_toggle_enable(bits_high)

    # Low bits
    bus.write_byte(I2C_ADDR, bits_low)
    lcd_toggle_enable(bits_low)


def lcd_toggle_enable(bits):
    # Toggle enable
    time.sleep(E_DELAY)
    bus.write_byte(I2C_ADDR, (bits | ENABLE))
    time.sleep(E_PULSE)
    bus.write_byte(I2C_ADDR, (bits & ~ENABLE))
    time.sleep(E_DELAY)


def lcd_string(message, line):
    # Send string to display

    message = message.ljust(LCD_WIDTH, " ")

    lcd_byte(line, LCD_CMD)

    for i in range(LCD_WIDTH):
        lcd_byte(ord(message[i]), LCD_CHR)

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  • I don't see any executable code
    – Milliways
    May 17, 2023 at 12:39
  • it's because it is part of a larger code that consists of around 300 lines. hence i uploaded only this section and its required libraries as this is most likely where the problem is May 17, 2023 at 12:42
  • If you know what the problem is why are you asking?
    – Milliways
    May 17, 2023 at 12:43
  • 1
    What is this LCD display? How do you know the backlight is i2c controlled? What does its spec say?
    – CoderMike
    May 17, 2023 at 13:19
  • 3
    Any explanatory information should be edited in to your question. I am not going to read comments to understand your question.
    – joan
    May 17, 2023 at 19:31

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