esp8266 lcd screen supplier

The IoD-09 modules feature a full colour 0.9” TFT LCD display. They are powered by the WiFi enabled ESP8266, which offers an array of functionality and options for any Designer / Integrator / User.

This tutorial shows how to use the I2C LCD (Liquid Crystal Display) with the ESP32 using Arduino IDE. We’ll show you how to wire the display, install the library and try sample code to write text on the LCD: static text, and scroll long messages. You can also use this guide with the ESP8266.

Additionally, it comes with a built-in potentiometer you can use to adjust the contrast between the background and the characters on the LCD. On a “regular” LCD you need to add a potentiometer to the circuit to adjust the contrast.

Before displaying text on the LCD, you need to find the LCD I2C address. With the LCD properly wired to the ESP32, upload the following I2C Scanner sketch.

Displaying static text on the LCD is very simple. All you have to do is select where you want the characters to be displayed on the screen, and then send the message to the display.

The next two lines set the number of columns and rows of your LCD display. If you’re using a display with another size, you should modify those variables.

To display a message on the screen, first you need to set the cursor to where you want your message to be written. The following line sets the cursor to the first column, first row.

Scrolling text on the LCD is specially useful when you want to display messages longer than 16 characters. The library comes with built-in functions that allows you to scroll text. However, many people experience problems with those functions because:

In a 16×2 LCD there are 32 blocks where you can display characters. Each block is made out of 5×8 tiny pixels. You can display custom characters by defining the state of each tiny pixel. For that, you can create a byte variable to hold  the state of each pixel.

In summary, in this tutorial we’ve shown you how to use an I2C LCD display with the ESP32/ESP8266 with Arduino IDE: how to display static text, scrolling text and custom characters. This tutorial also works with the Arduino board, you just need to change the pin assignment to use the Arduino I2C pins.

Than displays are the way to go. There are different kinds of displays like 7 Segment LED display, 4 Digit 7 Segment display, 8×8 Dot Matrix display, OLED display or the easiest and cheapest version the liquid crystal display (LCD).

Most LCD displays have either 2 rows with 16 characters per row or 4 rows with 20 characters per row. There are LCD screen with and without I2C module. I highly suggest the modules with I2C because the connection to the board is very easy and there are only 2 instead of 6 pins used. But we will cover the LCD screen with and without I2C module in this article.

The LCD display has an operating voltage between 4.7V and 5.3V with a current consumption of 1mA without backlight and 120mA with full backlight. There are version with a green and also with a blue backlight color. Each character of the display is build by a 5×8 pixel box and is therefore able to display custom generated characters. Because each character is build by (5×8=40) 40 pixels a 16×2 LCD display will have 16x2x40= 1280 pixels in total. The LCD module is able to operate in 8-bit and 4-bit mode. The difference between the 4-bit and 8-bit mode are the following:

If we use the LCD display version without I2C connection we have to add the potentiometer manually to control the contrast of the screen. The following picture shows the pinout of the LCD screen.

Also I added a table how to connect the LCD display with the Arduino Uno and the NodeMCU with a description of the LCD pin. To make it as easy as possible for you to connect your microcontroller to the display, you find the corresponding fritzing connection picture for the Arduino Uno and the NodeMCU in this chapter.

4RSD12D2Select command register to low when we are sending commands to the LCD like set the cursor to a specific location, clear the display or turn off the display.

8Data Pin 1 (d1)Data pins 0 to 7 forms an 8-bit data line. The Data Pins are connection to the Digital I/O pins of the microcontroller to send 8-bit data. These LCD’s can also operate on 4-bit mode in such case Data pin 4,5,6 and 7 will be left free.

Of cause we want to try the connection between the microcontroller and the LCD display. Therefore you find an example sketch in the Arduino IDE. The following section shows the code for the sketch and a picture of the running example, more or less because it is hard to make a picture of the screen ;-). The example prints “hello, world!” in the first line of the display and counts every second in the second row. We use the connection we described before for this example.

Looks very complicated to print data onto the LCD screen. But don’t worry like in most cases if it starts to get complicated, there is a library to make the word for us. This is also the case for the LCD display without I2C connection.

Like I told you, I would suggest the LCD modules with I2C because you only need 2 instead of 6 pins for the connection between display and microcontroller board. In the case you use the I2C communication between LCD and microcontroller, you need to know the I2C HEX address of the LCD. In this article I give you a step by step instruction how to find out the I2C HEX address of a device. There is also an article about the I2C communication protocol in detail.

On the backside is a 10 kΩ potentiometer build in to control the screen contrast. You do not have to add the potentiometer manually like in the version without I2C connection.

The following picture shows how to connect an I2C LCD display with an Arduino Uno. We will use exact this connection for all of the examples in this article.

To use the I2C LCD display we have to install the required library “LiquidCrystal_I2C” by Frank de Brabander. You find here an article how to install an external library via the Arduino IDE. After you installed the library successful you can include the library via: #include < LiquidCrystal_I2C.h>.

The LiquidCrystal library has 20 build in functions which are very handy when you want to work with the LCD display. In the following part of this article we go over all functions with a description as well as an example sketch and a short video that you can see what the function is doing.

LiquidCrystal_I2C()This function creates a variable of the type LiquidCrystal. The parameters of the function define the connection between the LCD display and the Arduino. You can use any of the Arduino digital pins to control the display. The order of the parameters is the following: LiquidCrystal(RS, R/W, Enable, d0, d1, d2, d3, d4, d5, d6, d7)

If you are using an LCD display with the I2C connection you do not define the connected pins because you do not connected to single pins but you define the HEX address and the display size: LiquidCrystal_I2C lcd(0x27, 20, 4);

xlcd.begin()The lcd.begin(cols, rows) function has to be called to define the kind of LCD display with the number of columns and rows. The function has to be called in the void setup() part of your sketch. For the 16x2 display you write lcd.begin(16,2) and for the 20x4 lcd.begin(20,4).

xxlcd.clear()The clear function clears any data on the LCD screen and positions the cursor in the upper-left corner. You can place this function in the setup function of your sketch to make sure that nothing is displayed on the display when you start your program.

xxlcd.setCursor()If you want to write text to your LCD display, you have to define the starting position of the character you want to print onto the LCD with function lcd.setCursor(col, row). Although you have to define the row the character should be displayed.

xxlcd.print()This function displays different data types: char, byte, int, long, or string. A string has to be in between quotation marks („“). Numbers can be printed without the quotation marks. Numbers can also be printed in different number systems lcd.print(data, BASE) with BIN for binary (base 2), DEC for decimal (base 10), OCT for octal (base 8), HEX for hexadecimal (base 16).

xlcd.println()This function displays also different data types: char, byte, int, long, or string like the function lcd.print() but lcd.println() prints always a newline to output stream.

xxlcd.display() / lcd.noDisplay()This function turn on and off any text or cursor on the display but does not delete the information from the memory. Therefore it is possible to turn the display on and off with this function.

xxlcd.scrollDisplayLeft() / lcd.scrollDisplayRight()This function scrolls the contents of the display (text and cursor) a one position to the left or to the right. After 40 spaces the function will loops back to the first character. With this function in the loop part of your sketch you can build a scrolling text function.

Scrolling text if you want to print more than 16 or 20 characters in one line, than the scrolling text function is very handy. First the substring with the maximum of characters per line is printed, moving the start column from the right to the left on the LCD screen. Than the first character is dropped and the next character is printed to the substring. This process repeats until the full string is displayed onto the screen.

xxlcd.autoscroll() / lcd.noAutoscroll()The autoscroll function turn on or off the functionality that each character is shifted by one position. The function can be used like the scrollDisplayLeft / scrollDisplayRight function.

xxlcd. leftToRight() / lcd.rightToLeft()The leftToRight and rightToLeft functions changes the direction for text written to the LCD. The default mode is from left to right which you do not have to define at the start of the sketch.

xxlcd.createChar()There is the possibility to create custom characters with the createChar function. How to create the custom characters is described in the following chapter of this article as well as an example.

xlcd.backlight()The backlight function is useful if you do not want to turn off the whole display (see lcd.display()) and therefore only switch on and off the backlight. But before you can use this function you have to define the backlight pin with the function setBacklightPin(pin, polarity).

xlcd.moveCursorLeft() / lcd.moveCursorRight()This function let you move the curser to the left and to the right. To use this function useful you have to combine it with lcd.setCursor() because otherwise there is not cursor to move left or right. For our example we also use the function lcd.cursor() to make the cursor visible.

xlcd.on() / lcd.off()This function switches the LCD display on and off. It will switch on/off the LCD controller and the backlight. This method has the same effect of calling display/noDisplay and backlight/noBacklight.

The following code shows you the Arduino program to use all three LCD display functions of the library divided into three separate functions. Also the video after the program shows the functions in action.

The creation of custom characters is very easy if you use the previous mentioned libraries. The LiquidCrystal and also the LiquidCrystal_I2C library have the function “lcd.createChar()” to create a custom character out of the 5×8 pixels of one character. To design your own characters, you need to make a binary matrix of your custom character from an LCD character generator or map it yourself. This code creates a wiggling man.

In the section of the LCD display pinout without I2C we saw that if we set the RS pin to how, that we are able to send commands to the LCD. These commands are send by the data pins and represented by the following table as HEX code.

For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.

To install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE menus, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.

The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.

I was able to compile this code successfully and save it to the board using Arduino IDE, but nothing display on the screen, the backlights are working fine.

In the setup () function, we initialize the variable "dht,” which is responsible for the communication with the humidity sensor and temperature. We will also initialize the "display" variable that is used to communicate with the LCD module.

In the loop () function, we will retrieve the humidity and temperatures read by the sensor and written on the screen at the specific location. At each interval of 5 seconds, the value is read from the sensor and written on the screen.void loop()

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