multiple lcd displays arduino brands

I have seen some i2c LCD backpacks like that before. Some have the solder jumpers on the back of the board and some don"t have a way to set it all since the address pins are directly wired to GND or VCC, I consider both a poor design.

The circuit diagram for interfacing of three LCDs with Arduino is shown in Fig. 1. It is built around popular Arduino Uno board (BOARD1), three 16×2 LCDs (LCD1 through LCD3), three 10-kilo-ohm presets (VR1 through VR3) and a few other components. The Arduino board is the brain of the circuit, which displays data on the three LCDs simultaneously or individually depending on the requirement.

As shown in Fig. 1, the 5V and ground required to operate the circuit are provided by the Arduino Uno board. All the three LCDs are configured in 4-bit mode. Common data lines of all the LCDs (D4 through D7) are connected to digital pins 4 through 7 of Arduino Uno. RS and EN control pins of LCDs are connected to different digital pins of Board1. Pin-to-pin connections between LCDs and the Arduino Uno board are shown in Table I.

If you want to display data on the first LCD (LCD1) only, connect RS and EN pins of LCD1 to Arduino using SJ1 and SJ2 across connector CON1. Remove SJ3 through SJ6 so that RS and EN pins of the other two LCDs are not used. Thus it is possible to send data to the selected LCD while using common data lines of the LCDs.

To display data on the second LCD (LCD2) only, connect RS and EN pins of LCD2 using SJ3 and SJ4. Remove SJ1, SJ2, SJ5 and SJ6 to ensure that RS and EN pins of the other two LCDs are not used.

Similarly, to display data on the third LCD (LCD3) only, connect RS and EN pins of LCD3 using SJ5 and SJ6, ensuring that all other RS and EN pins are not used.

When you want to display data on all the three LCDs, connect all the shorting jumpers (SJ1 through SJ6) to the Arduino Uno board. Refer Table II for jumper settings and data displays on different LCDs.

The software (multi.ino) for interfacing of the multiple LCDs using Arduino is written in Arduino programming language. The Arduino Uno is programmed using Arduino IDE software.

An actual-size PCB layout for interfacing multiple LCDs with Arduino is shown in Fig. 2 and its components layout in Fig. 3. After assembling the circuit on the PCB, connect Arduino Uno and the PCB using external male-to-male jumpers. Then solder the 16-pin bergstrip male connector on the LCD and 16-pin bergstrip female connector on the PCB. Fix all the LCDs on the PCB in the space provided.

After assembling the circuit, connect the Arduino board to your computer with standard USB cable. Compile the source code (multi.ino) and upload it to the Arduino Uno board. Connect shorting jumpers SJ1 through SJ6 on the respective connector as explained above.

You can see data display on LCD1 or all the LCDs as per the jumper settings (refer Table II). Vary contrast-control preset VR1 left and right until you get clearly visible text on LCD1.

For HD44780 based displays all the data, register select and read/write pins can be shared. A display only exists at the moment the E pin is toggled. They are designed to share a microprocessor"s data bus.

So if you have 50 displays then you can (theoretically, see "fan out" below) run them from 50 "E" pins plus 6 (or 10 depending on if you want to run in 4 or 8 bit mode) shared pins.

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.

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.

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!

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.

Creating custom characters has never been easier! We have created a small application called Custom Character Generator. Can you see the blue grid below? You can click on any 5×8 pixel to set/clear that particular pixel. And as you click, the code for the character is generated next to the grid. This code can be used directly in your Arduino sketch.

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.

This article gives you a step-by-step guide to becoming a pro in using Liquid Crystal Display. We will use a free Arduino Simulator to try all the examples without leaving your PC. No hardware is needed.

You can see that the first eight characters are user-defined. It allows you to create custom shapes and store them. You will see how to create custom characters and load them in your following Arduino projects. Let us start with a basic example.

We will print a simple text on the LCD using Arduino UNO in this example. In this case, you control what is displayed on the Arduino readily. You only need four cables. Power, Ground, I2C data, and I2C clock.

The below line code adds the LCD library to your project. This consists of all the LCD-related functions. Since we are using the I2C version, we have included the standard LCD library made for the I2C version.#include

The following line of the code resets and initializes all the LCD registers and prepares them for project usage. This function will be called only once in thesetup()function.lcd.init();

To turn on the backlight, you can use the below code. You will be able to see the contents of the display without a backlight, too, if it is a green LCD. Backlight, nevertheless, makes the project more beautiful and reading crisper.lcd.backlight();

The first parameter tells the position column-wise (0indicated first place,1indicates the second place, and so on). The second parameter tells the row number. We have only two rows (0and1).lcd.setCursor(1, 0);

This completes a basic introduction to the LCD as well as an example project to start the LCD exploration. In the coming sections, we will see different projects as soon as possible