D-0006

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PCF8574T LCD Driver Board

Description

The PCF8574T IO Expansion Board is used as remote 8-bit I/O expander for I2C-bus.
Up to 8 PCF8574T IO Expansion Board can be connected to the I2C-bus, providing up to 64 I/O ports.
The PCF8574T IO Expansion Board features allowing the use of multi module connected to the I2C bus at the same time by connecting the pinheader and connector.
There is a small potentiometer onboard, which can adjust the backlight of LCD1602 or LCD2004, and a jumper cap to control the switch of the LED light.

Features

PCF8574T Chip
I2C interface
8-bit parallel port
Potentiometer Backlight control
LED jumper switch
Default I2C address: 0x27

Gallery

Dimenssion

Package Includes

1 x PCF8574T LCD Driver Board

Reference

PCF8574T Chip Datasheet: File:PCF8574T Datasheet.pdf
WiringPi: [ http://wiringpi.com/extensions/i2c-pcf8574/ ]
telecnatron:[ https://telecnatron.com/articles/Utility-To-Control-1602-LCD-On-Raspberry-Pi-Via-A-PCF8574-I2C-Backpack-Module/index.html]
Circuitbasics:[ https://www.circuitbasics.com/raspberry-pi-i2c-lcd-set-up-and-programming/ ]

Demo Code For Handle PCF8574T

Download and reinstall wiringPi liberary

 
sudo apt -y purge wiringpi
hash -r
cd /tmp
wget https://project-downloads.drogon.net/wiringpi-latest.deb
sudo dpkg -i wiringpi-latest.deb

C++ language

#include <stdio.h>
#include <time.h>
#include <string>

#include <wiringPi.h>
#include <pcf8574.h>

using namespace std;
int main (int argc, char *argv[]){
	printf("Raspberry Pi initializing...\n");

        wiringPiSetup();
	pcf8574Setup(100, 0x38);

	for (int i = 0; i < 8; ++i){
    		pinMode(100 + i, OUTPUT);
	}

        int b=0;
        while( 1==1 ){
                printf("LOOP %u\n", b);
                for (int i = 0; i < 8; ++i){
                    digitalWrite(100 + i, i==b ? 0 : 1);
                }
                b++;
		if( b >= 8 ) b=0;
		delay(1000);

	}

	delay(1000);
	digitalWrite(100 + 0, 0);

	delay(1000);
        digitalWrite(100 + 0, 1);

	return 0;
}

Compile and run it.

g++ pcf8574.cpp -o pcf8574 -lwiringPi -std=c++11
./pcf8574

Python Demo Code

Copy following code and save it as: I2C_LCD_driver.py

# -*- coding: utf-8 -*-
# Original code found at:
# https://gist.github.com/DenisFromHR/cc863375a6e19dce359d

"""
Compiled, mashed and generally mutilated 2014-2015 by Denis Pleic
Made available under GNU GENERAL PUBLIC LICENSE

# Modified Python I2C library for Raspberry Pi
# as found on http://www.recantha.co.uk/blog/?p=4849
# Joined existing 'i2c_lib.py' and 'lcddriver.py' into a single library
# added bits and pieces from various sources
# By DenisFromHR (Denis Pleic)
# 2015-02-10, ver 0.1

"""

# i2c bus (0 -- original Pi, 1 -- Rev 2 Pi)
# I2CBUS = 0
I2CBUS = 1

# LCD Address
#ADDRESS = 0x3f
ADDRESS = 0x27

import smbus
from time import sleep

class i2c_device:
   def __init__(self, addr, port=I2CBUS):
      self.addr = addr
      self.bus = smbus.SMBus(port)

# Write a single command
   def write_cmd(self, cmd):
      self.bus.write_byte(self.addr, cmd)
      sleep(0.0001)

# Write a command and argument
   def write_cmd_arg(self, cmd, data):
      self.bus.write_byte_data(self.addr, cmd, data)
      sleep(0.0001)

# Write a block of data
   def write_block_data(self, cmd, data):
      self.bus.write_block_data(self.addr, cmd, data)
      sleep(0.0001)

# Read a single byte
   def read(self):
      return self.bus.read_byte(self.addr)

# Read
   def read_data(self, cmd):
      return self.bus.read_byte_data(self.addr, cmd)

# Read a block of data
   def read_block_data(self, cmd):
      return self.bus.read_block_data(self.addr, cmd)


# 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
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

# flags for backlight control
LCD_BACKLIGHT = 0x08
LCD_NOBACKLIGHT = 0x00

En = 0b00000100 # Enable bit
Rw = 0b00000010 # Read/Write bit
Rs = 0b00000001 # Register select bit

class lcd:
   #initializes objects and lcd
   def __init__(self):
      self.lcd_device = i2c_device(ADDRESS)

      self.lcd_write(0x03)
      self.lcd_write(0x03)
      self.lcd_write(0x03)
      self.lcd_write(0x02)

      self.lcd_write(LCD_FUNCTIONSET | LCD_2LINE | LCD_5x8DOTS | LCD_4BITMODE)
      self.lcd_write(LCD_DISPLAYCONTROL | LCD_DISPLAYON)
      self.lcd_write(LCD_CLEARDISPLAY)
      self.lcd_write(LCD_ENTRYMODESET | LCD_ENTRYLEFT)
      sleep(0.2)


   # clocks EN to latch command
   def lcd_strobe(self, data):
      self.lcd_device.write_cmd(data | En | LCD_BACKLIGHT)
      sleep(.0005)
      self.lcd_device.write_cmd(((data & ~En) | LCD_BACKLIGHT))
      sleep(.0001)

   def lcd_write_four_bits(self, data):
      self.lcd_device.write_cmd(data | LCD_BACKLIGHT)
      self.lcd_strobe(data)

   # write a command to lcd
   def lcd_write(self, cmd, mode=0):
      self.lcd_write_four_bits(mode | (cmd & 0xF0))
      self.lcd_write_four_bits(mode | ((cmd << 4) & 0xF0))

   # write a character to lcd (or character rom) 0x09: backlight | RS=DR<
   # works!
   def lcd_write_char(self, charvalue, mode=1):
      self.lcd_write_four_bits(mode | (charvalue & 0xF0))
      self.lcd_write_four_bits(mode | ((charvalue << 4) & 0xF0))
  
   # put string function with optional char positioning
   def lcd_display_string(self, string, line=1, pos=0):
    if line == 1:
      pos_new = pos
    elif line == 2:
      pos_new = 0x40 + pos
    elif line == 3:
      pos_new = 0x14 + pos
    elif line == 4:
      pos_new = 0x54 + pos

    self.lcd_write(0x80 + pos_new)

    for char in string:
      self.lcd_write(ord(char), Rs)

   # clear lcd and set to home
   def lcd_clear(self):
      self.lcd_write(LCD_CLEARDISPLAY)
      self.lcd_write(LCD_RETURNHOME)

   # define backlight on/off (lcd.backlight(1); off= lcd.backlight(0)
   def backlight(self, state): # for state, 1 = on, 0 = off
      if state == 1:
         self.lcd_device.write_cmd(LCD_BACKLIGHT)
      elif state == 0:
         self.lcd_device.write_cmd(LCD_NOBACKLIGHT)

   # add custom characters (0 - 7)
   def lcd_load_custom_chars(self, fontdata):
      self.lcd_write(0x40);
      for char in fontdata:
         for line in char:
            self.lcd_write_char(line)

Create a file named: lcd1602.py and paste following code:

import I2C_LCD_driver
from time import * 

mylcd = I2C_LCD_driver.lcd()
# There are 16 character that you can put on the screen and 2 lines avaliable. 
mylcd.lcd_display_string("00000000000000000", 1, 0)
mylcd.lcd_display_string("00000000000000000", 2, 0)

Run it.

python lcd1602.py

Application Scenario

Control-Any-Devices-Using-Raspberry-PI-and-PCF8574: [ https://www.instructables.com/id/Control-Any-Devices-Using-Raspberry-PI-and-PCF8574/ ]
I2C-1602-LCD: [1]

Keywords

PCF8574T, LCD1602, driver board, LCD driver board

D-0006

Contents

PCF8574T LCD Driver Board

Description

Features

Gallery

Dimenssion

Package Includes

Reference

Demo Code For Handle PCF8574T

Python Demo Code

Application Scenario

Keywords

Navigation menu

D-0006

PCF8574T LCD Driver Board

Description

Features

Gallery

Dimenssion

Package Includes

Reference

Demo Code For Handle PCF8574T

Python Demo Code

Application Scenario

Keywords

Navigation menu

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