There are some preset commands instructions in LCD, which we need to send to LCD through some microcontroller. Some important command instructions are given below:

OLED vs LCDwhich is better for eyes

So Now, we know that each character has (5*8=40) 40 Pixels and for 32 Characters we will have (32*40) 1280 Pixels. Further, the LCD should also be instructed about the Position of the Pixels.

In my project i have to connect a relay to digital pins of the arduino uno board. But I couldn't control the relay since the output is 2.18v. Could you please guide me what should i do.

Lcd vs oled power consumption vsqled

As shown in the circuit if you use a transistor like BC547 and current limiting resistor, you should be able to toggle the relay without any problem.

QLEDvs OLED power consumption

The reason is that when you trigger a relay directly from Arduino, the current provided by the I/O pin will not be enough and hence there will be a voltage drop (In your case 2.7) on your Arduino pin.

AMOLEDvs LCDbatteryconsumption

The LCD can work in two different modes, namely the 4-bit mode and the 8-bit mode. In 4 bit mode we send the data nibble by nibble, first upper nibble and then lower nibble. For those of you who don’t know what a nibble is: a nibble is a group of four bits, so the lower four bits (D0-D3) of a byte form the lower nibble while the upper four bits (D4-D7) of a byte form the higher nibble. This enables us to send 8 bit data.

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It will be a hectic task to handle everything with the help of MCU, hence an Interface IC like HD44780 is used, which is mounted on LCD Module itself. The function of this IC is to get the Commands and Data from the MCU and process them to display meaningful information onto our LCD Screen.

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16×2 LCD is named so because; it has 16 Columns and 2 Rows. There are a lot of combinations available like, 8×1, 8×2, 10×2, 16×1, etc. But the most used one is the 16*2 LCD, hence we are using it here.

All the above mentioned LCD display will have 16 Pins and the programming approach is also the same and hence the choice is left to you. Below is the Pinout and Pin Description of 16x2 LCD Module:

It is okay if you do not understand the function of all the pins, I will be explaining in detail below. Now, let us turn back our LCD:

Samsunglcd vs oled power consumption

You should not drive the Relay directly from an Arduino I/O pin.  If your Relay is a 5V relay you can use the circuit shown in the link below

These black circles consist of an interface IC and its associated components to help us use this LCD with the MCU. Because our LCD is a 16*2 Dot matrix LCD and so it will have (16*2=32) 32 characters in total and each character will be made of 5*8 Pixel Dots.  A Single character with all its Pixels enabled is shown in the below picture.

The Interface IC present in most of the LCD is HD44780U, in order to program our LCD we should learn the complete datasheet of the IC. The datasheet is given here.

Now you must have guessed it, Yes 8-bit mode is faster and flawless than 4-bit mode. But the major drawback is that it needs 8 data lines connected to the microcontroller. This will make us run out of I/O pins on our MCU, so 4-bit mode is widely used. No control pins are used to set these modes. It's just the way of programming that change.

Tank you for your interesting and usefull articel. Question: Is it possible to find out a pinout from an older, used LCD display? I have different, old displays I got out of still working but sorted out electronic gears like server nodes, video recorders , ... , you name it ... . Of course, I would like to use them and I asked myself, if it is possible, to find out how the pinout for that devcices is.

As said, the LCD itself consists of an Interface IC. The MCU can either read or write to this interface IC. Most of the times we will be just writing to the IC, since reading will make it more complex and such scenarios are very rare. Information like position of cursor, status completion interrupts etc. can be read if required, but it is out of the scope of this tutorial.

https://circuitdigest.com/fullimage?i=circuitdiagram_mic/Visitor-Counter-Circuit1.gif (Check the relay driving part alone)