pcf8574 i2c lcd module manufacturer

A regular LCD requires a lot of wires (parallel interface) to be connected with a Microcontroller.The Serial LCD  backpack built on PCF8574 IC uses the I2C bus to convert  the parallel interface to a serial one.This needs only2 wires SDA & SCL , apart from the power connections.

The blue preset is to adjust the contrast of the LCD. The black jumper on the left is to enable the Backlight of LCD. The I2C device has a HEX address by which a microcontroller can communicate with it.This is set by the 3 bits A0,A1 ,A2 .If no jumper is present , it is HIGH &  a jumper means LOW. By default all the 3 jumpers are open . ie., A0,A1 A2 all are 1s.

The I2C bus has 2 bidirectional active wires SDA & SCL .They are joined to positive supply through a pull up resistor of 4k7.When the bus is  idle both lines are pulled high.

lcd.setBacklightPin(HIGH);  makes the P3 pin go High, which turns on the NPN transistor.This provides GND to the LED pin of LCD As the other LED pin is already connected to Vcc through the jumper , the LCD backlight glows.

This LCD I2C interface adapter can be added to a 16 x 2 or 20 x 4 character LCD display with a standard parallel interface to make it I2C compatible.  It can also be repurposed for other I2C to parallel tasks.

By default, the industry standard HD44780 compatible 16 x 2 and 20 x 4 character LCD displays require 4 or 8 parallel data lines to drive them along with a couple of pins for chip select and chip enable.  This consumes a lot of pins on the MCU.  This adapter board reduces the data pin requirements to only 2 pins which can also be shared with other I2C devices.

The backlight can be controlled ON/OFF, but the intensity is not directly controllable though the I2C interface.  Some modules have a jumper on the board that supplies Vcc power to the backlight.  That jumper can be removed and a voltage applied to the header pin nearest the ‘LED’ markings on the board to provide power to the backlight separately.  Note:  Some modules do not have this header / jumper installed, instead the solder pads have a trace connecting them.  It is possible to cut the trace between the pads and add header pins if desired.

The PCF8574 is a generic I2C to 8-bit I/O device and the module can be repurposed for other uses besides driving LCD modules.  Max I2C clock frequency is 100kHz which makes it most suited to lower speed applications.

VCC =  Connect to 5V.  This can come from the MCU or be a separate power supply.  Some LCD may operate at 3.3V and this module can also operate at 3.3V

The pin-out of the header which is soldered to the LCD follows for reference, but in general you don’t need to worry about it as the I2C interface board and software library takes care of this interface unless you are adapting the module for another use.  These pins are listed starting at the I2C header end of the board.

To use the adapter with an LCD, you will need to insert the 16-pin header into the 16 solder pad holes on the back of the LCD and solder them in place on the front side.  The pins are long and can be cut off before or after soldering.

Soldering the module on is easy to do, but if you already have other pins in those holes, they will need to be removed first before this board can be added.  The picture below shows the adapter mounted to the back of an LCD2004 4 x 20 character LCD.

This is the same module used on our I2C compatible LCD displays we sell and is well supported using the LiquidCrystal_I2C.h and similar libraries.  For using the board with software, you can check out one of the LCDs below that already have this module installed.

The PCF8574 itself is a general purpose 8-bit I/O expander for the I2C bus.  The reverse engineered schematics are provided here mainly for those who may want to adapt the module to other applications.  The I2C bus on this module is limited to a 100kHz clock frequency.

SMALL ISSUE: I"ve used a npn transistor for backlight, the library is written for a pnp transistor. This means that the command lcd.setBaclight(LOW) turns the backlight on and lcd.setBacklight(HIGH) switchs the backlight off.

16×2 LCD is an alphanumeric display that can show up to 32 characters on a single screen. You can display more characters by scrolling the texts one by one. We have already seen how to connect LCD Display directly with the Arduino using 4bit and 8bit modes in our previous tutorial. But those two modes will utilize many numbers of GPIO Pins of our Arduino and we would have to end up with less number of pins for other sensors and actuators.

To overcome this problem we use LCD I2C backpack with our LCD. This I2C Backpack uses PCF8574 Remote 8 bit I/O Expander. It translates the data received from the I2C Bus into Parallel data that is needed for the LCD Display.

Inter-integrated Circuit (in short I2C) is a two-wire short distance communication protocol. You can use multiple slave devices in the same two wires with one or more master controllers. You may wonder how does the master identifies which slave does the data to be sent. In I2C the external devices have an I2C address for different external devices like LCD Backpack, OLED Display, etc. By using the address the data is sent to the specific device connected on the same I2C Bus.

The message is broken into two frames and sent serially via the I2C Bus. The first frame contains the address, once the address matches with any device on I2C bus, that device will send an acknowledge signal to the master. After receiving the acknowledgment from the slave the data bits are sent. By this method an I2C bus works.

There are totally 16 pins in an LCD Display. You can use directly all the pins in 8-bit mode with Arduino or 12 pins using 4-bit mode. In this tutorial, we use the I2C module for LCD and multiplex it into just 4 pins. This pin details might not be useful while using I2C Method but this is the actual pin details of all the pins in LCD Display.

RS – Register select. Specify what we are sending Command or Data. Sets to 0 for Command mode like setCursor, LCD Clear, TurnOFF LCD. Set 1 for data mode like sending Data/Characters.

First, we need to find the address of our I2C LCD Backpack. For that, we will be using I2C Scanner code to display the address in the serial monitor. Upload the following code, then note down the I2C address from the serial monitor.#include

In my case, it is 0x27. Node down the address displayed for you. Mostly it will be 0x27 only. In case you have another I2C device connected on the same bus it will show that address too.

Download .zip LiquidCrystal_I2C library by Frank de Brabander from hereand Install it in IDE by navigating Sketch>Include Library>Add .zip library and choose the downloaded LiquidCrystal_I2C.zip library file.

Now the LCD I2C library is installed. We need to define and initialize the library using its associated functions. The steps is as follows. Or you can copy the code given below to print Hello World example.

Set the address that we copied from I2C Scanner code. The address I got is 0x27 so I replaced it to 0x27 in the following lineLiquidCrystal_I2C lcd(0x27, 16, 2);

In the above code, we have created an LCD object for ‘LiquidCrystal_I2C’. So you can use directly use the regular LCD functions to work with I2C like lcd.begin(), lcd.print(“”), etc.

To print a string we use lcd.print() function with string in its parameters. This prints ‘Factory’ string in the 1st row and ‘Forward’ in the 2nd row.

This function sets the cursor on 7th column and 2nd row. Printing the string will gets displayed from this location on LCD.lcd.setCursor(6,1); // Sets cursor column and row position

By Using lcd.blink() function we can make the cursor blinking on LCD. To turn off the blinking cursor we use lcd.noBlink() function.lcd.blink(); //Blinking cursor

Use lcd.cursor() function for printing an underscore symbol. It is also used for notifying users to enter some values.lcd.cursor(); // Prints an underscore symbol

I2C Adapter Board fits right on the back of standard LC character display modules with 1 x Hitachi HD44780 or compatible display controller. The on-board PCF8574 or PCF8574A 8-bit I/O expander encodes the signals for the 4 data bits, the read/write select, register select, the enable signal, and the backlight-ON signal.

The supported I2C addresses depend on the version of the expander IC – please refer to the manufacturer PDF or find plenty of information online (for example Arduino forum).

Additional circuit design information: The I2C bus on development boards like the Arduino series of boards doesn’t have the necessary pull-up resistors already installed. To make the I2C connection happen, you will need pull-up resistors from VDD to SDA and SCL. The value of these resistors is not critical, as long as the connections are short and the data rate low. For just 1 or 2 displays on 5V logic level is a value of 2k to 20k a good choice.

About products and suppliers:Alibaba.com offers 8921 i2c lcd products. About 25% % of these are lcd modules, 14%% are oled/e-paper modules, and 6%% are lcd touch screen.

A wide variety of i2c lcd options are available to you, such as original manufacturer, odm and agency.You can also choose from standard, tft and character i2c lcd,

If you’ve ever tried to connect an LCD display to an Arduino, you might have noticed that it consumes a lot of pins on the Arduino. Even in 4-bit mode, the Arduino still requires a total of seven connections – which is half of the Arduino’s available digital I/O pins.

The solution is to use an I2C LCD display. It consumes only two I/O pins that are not even part of the set of digital I/O pins and can be shared with other I2C devices as well.

True to their name, these LCDs are ideal for displaying only text/characters. A 16×2 character LCD, for example, has an LED backlight and can display 32 ASCII characters in two rows of 16 characters each.

At the heart of the adapter is an 8-bit I/O expander chip – PCF8574. This chip converts the I2C data from an Arduino into the parallel data required for an LCD display.

If you are using multiple devices on the same I2C bus, you may need to set a different I2C address for the LCD adapter so that it does not conflict with another I2C device.

An important point here is that several companies manufacture the same PCF8574 chip, Texas Instruments and NXP Semiconductors, to name a few. And the I2C address of your LCD depends on the chip manufacturer.

According to the Texas Instruments’ datasheet, the three address selection bits (A0, A1 and A2) are placed at the end of the 7-bit I2C address register.

According to the NXP Semiconductors’ datasheet, the three address selection bits (A0, A1 and A2) are also placed at the end of the 7-bit I2C address register. But the other bits in the address register are different.

So your LCD probably has a default I2C address 0x27Hex or 0x3FHex. However it is recommended that you find out the actual I2C address of the LCD before using it.

Connecting an I2C LCD is much easier than connecting a standard LCD. You only need to connect 4 pins instead of 12. Start by connecting the VCC pin to the 5V output on the Arduino and GND to ground.

Now we are left with the pins which are used for I2C communication. Note that each Arduino board has different I2C pins that must be connected accordingly. On Arduino boards with the R3 layout, the SDA (data line) and SCL (clock line) are on the pin headers close to the AREF pin. They are also known as A5 (SCL) and A4 (SDA).

After wiring up the LCD you’ll need to adjust the contrast of the display. On the I2C module you will find a potentiometer that you can rotate with a small screwdriver.

Plug in the Arduino’s USB connector to power the LCD. You will see the backlight lit up. Now as you turn the knob on the potentiometer, you will start to see the first row of rectangles. If that happens, Congratulations! Your LCD is working fine.

To drive an I2C LCD you must first install a library called LiquidCrystal_I2C. This library is an enhanced version of the LiquidCrystal library that comes with your Arduino IDE.

Filter your search by typing ‘liquidcrystal‘. There should be some entries. Look for the LiquidCrystal I2C library by Frank de Brabander. Click on that entry, and then select Install.

The I2C address of your LCD depends on the manufacturer, as mentioned earlier. If your LCD has a Texas Instruments’ PCF8574 chip, its default I2C address is 0x27Hex. If your LCD has NXP Semiconductors’ PCF8574 chip, its default I2C address is 0x3FHex.

So your LCD probably has I2C address 0x27Hex or 0x3FHex. However it is recommended that you find out the actual I2C address of the LCD before using it. Luckily there’s an easy way to do this, thanks to the Nick Gammon.

But, before you proceed to upload the sketch, you need to make a small change to make it work for you. You must pass the I2C address of your LCD and the dimensions of the display to the constructor of the LiquidCrystal_I2C class. If you are using a 16×2 character LCD, pass the 16 and 2; If you’re using a 20×4 LCD, pass 20 and 4. You got the point!

First of all an object of LiquidCrystal_I2C class is created. This object takes three parameters LiquidCrystal_I2C(address, columns, rows). This is where you need to enter the address you found earlier, and the dimensions of the display.

In ‘setup’ we call three functions. The first function is init(). It initializes the LCD object. The second function is clear(). This clears the LCD screen and moves the cursor to the top left corner. And third, the backlight() function turns on the LCD backlight.

After that we set the cursor position to the third column of the first row by calling the function lcd.setCursor(2, 0). The cursor position specifies the location where you want the new text to be displayed on the LCD. The upper left corner is assumed to be col=0, row=0.

There are some useful functions you can use with LiquidCrystal_I2C objects. Some of them are listed below:lcd.home() function is used to position the cursor in the upper-left of the LCD without clearing the display.

lcd.scrollDisplayRight() function scrolls the contents of the display one space to the right. If you want the text to scroll continuously, you have to use this function inside a for loop.

lcd.scrollDisplayLeft() function scrolls the contents of the display one space to the left. Similar to above function, use this inside a for loop for continuous scrolling.

If you find the characters on the display dull and boring, you can create your own custom characters (glyphs) and symbols for your LCD. They are extremely useful when you want to display a character that is not part of the standard ASCII character set.

CGROM is used to store all permanent fonts that are displayed using their ASCII codes. For example, if we send 0x41 to the LCD, the letter ‘A’ will be printed on the display.

CGRAM is another memory used to store user defined characters. This RAM is limited to 64 bytes. For a 5×8 pixel based LCD, only 8 user-defined characters can be stored in CGRAM. And for 5×10 pixel based LCD only 4 user-defined characters can be stored.

After the library is included and the LCD object is created, custom character arrays are defined. The array consists of 8 bytes, each byte representing a row of a 5×8 LED matrix. In this sketch, eight custom characters have been created.

These modules are currently supplied with a default I2C address of either 0x27 or 0x3F. To determine which version you have check the black I2C adaptor board on the underside of the module. If there a 3 sets of pads labelled A0, A1, & A2 then the default address will be 0x3F. If there are no pads the default address will be 0x27.

This is another great IIC/I2C/TWI/SPI Serial Interface. As the pin resources of Arduino controller is limited, your project may be not able to use normal LCD shield after connected with a certain quantity of sensors or SD card. However, with this I2C interface module, you will be able to realize data display via only 2 wires. If you already has I2C devices in your project, this LCD module actually cost no more resources at all. It is fantastic for Arduino based project.

This is a RoHS compliant I2C Serial LCD Daughter board that can be connected to a standard 16×2 or 20×4 Character Display Module that supports 4-bit mode. All Character Modules sold on our site support 4-bit mode, and nearly all commercially available 16×2 and 20×4 line character modules support it too.

This board has a PCF8574 I2C chip that converts I2C serial data to parallel data for the LCD display. There are many examples on the internet for using this board with Arduino. Do a search for “Arduino LCD PCF8574“. The I2C address is 0x3F by default, but this can be changed via 3 solder jumpers provided on the board. This allows up to 3 LCD displays to be controlled via a single I2C bus (giving each one it’s own address)