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The Simple Dynamics of UART Arduino

UART is one of the most common and pretty basic hardware communication peripherals that electricians and makers implement in microcontrollers. Similarly, Arduinos contain UART peripherals too. Have you ever used a UART Arduino before? Are you planning on using one or your project? Would you like to know all about this incredible device? Well, in this article, we shall dig deep into UART Arduino and discuss issues such as:

  • What is a UART Arduino?
  • How does a UART Arduino work?
  • How does communication in UART Arduino occur?
  • Some Arduino UART examples and so on.

After reading this article, you will have all you require on UART Arduino and more. Hence follow along as we explore this great topic!


If you love tech, then you most probably have heard of the term Arduino, maybe from a lecturer, on the internet, or from a friend. Well, Arduino refers to an open-source electronic platform basing on hardware and software that is easy to use. Arduino boards can read inputs (for example, when you press a button or when light flashes on a sensor) and then turn the input into output (for example, activating an LED after pressing the button or turning on a motor after detecting light). You can easily tell your Arduino board what action to take by inputting a set of instructions into the board’s microcontroller. To input this instruction, you implement Arduino programming language, basing on wiring, and Arduino software for processing.

Arduino, over the years, has been the brain of a lot of projects; we are talking about thousands and thousands of projects. The device has been in use for simple tasks and complex scientific projects, with its efficiency only growing stronger by the day. What’s more, Arduino’s open-source platform has brought together a community of:

  • Professionals
  • Programmers
  • Artists
  • Hobbyist
  • Students

The Arduino community enables access to great Arduino knowledge to both experts and beginners. Since this community keeps on growing and each person can contribute, the knowledge base keeps expanding too!

The development of Arduino happened at the Ivrea Interaction Design Institute. Many anticipated an easy tool to implement for faster prototyping. The aim for the device was to help students who had no programming and electronic background. However, as soon as these boards hit the wider community, they grew like wildfire. The board started to change to adapt to the newly found challenges. The boards evolved from simple eight-bit boards to products for wearable, IoT applications, embedded environments, and 3D printing.

Why is Arduino Super Popular?

uart arduino code

These boards are pretty simple to use, and they are also easily accessible to users. The Arduino software is also super easy to use for the novice, yet it is also flexible enough for implementation by advanced users. Arduino also dramatically simplifies the tedious processing of working with microcontrollers. Due to these reasons, Arduino has been implemented in many different applications and projects.

Arduino also has some added advantages that it offers to interested amateurs, students, and teachers over the system. They include:

  1. Inexpensive – compared to other microcontrollers platforms, Arduino boards are relatively inexpensive. Pre-assembled Arduino boards cost less than fifty dollars, while those not assembled cost even less than this, pretty cheap.
  2. Cross-platform – Arduino software can run on Linux, Macintosh OSX, and Windows operating systems.
  3. Clear and straightforward programming environment – Arduino software is pretty easy to use, even for beginners.
  4. Extensible, open-source software – Arduino software is open source which means that experienced programmers can expand the software’s capabilities. You can expand the software using C++ libraries.

Now that we know what Arduino is, let us look at UART Arduino and see the difference.

What is a UART Arduino?

UART (Universal Asynchronous Reception and Transmission) is a pretty simple protocol for serial communication that lets hosts communicate with different serial devices. UART supports serial, asynchronous, and bidirectional data transmission. It uses three lines to communicate efficiently, namely:

  • TX (Pin 1) –  used for transmission  
  • RX (Pin 0) –used to receive
  • GND – common ground

It is possible to connect the two between two separate devices, for example, USB on an Arduino and computer. UART is available on every type of Arduino board which in turn helps the Arduino in terms of communication with a pc because of its onboard USB to Serial converter.

If you write an Arduino program using Linux, Windows, or Mac OS, all you have to do to use it with your Arduino is to connect the two (your Arduino and your computer) using their USB ports.

Arduino UART Interface

An Arduino can have one or multiple UART pins; this depends upon the type of board in use. In this article, the project that we shall go through mainly implements an Arduino Uno; this Arduino board has one UART interface, which is present on TXO (pin 1) and RXO(pin 0). The TX0 and RX0 communicate as indicated earlier (as TX and RX). The two work together to ensure that communication between two UARTs is successful.

How many UART ports on Arduino uno come pre-installed?

Arduino uno has only one hardware UART port, this port is permanently engaged with the IDE and serial monitor. However, you can still create another port via software instructions. Using this port you can connect a second UART port driven device like a HC12 Radio module, a Bluetooth module et cetera.

However, there is a downside to this software port. It requires a great amount of help from the Arduino controller to efficiently send and receive data, this makes the port slow and less efficient compared to the hardware port.

Logic levels of UART

Logic levels of UART might differ between different manufacturers. Take, for example, Arduino Unos have a 5-V logic level, but the logic level of the computer’s RS232 port stands at +/-12 V. Therefore if you connect an Arduino Uno directly into an RS232 port, you might end up damaging the Arduino. If two UART devices do not have equal logic levels, you should use a logic level converter circuit to connect the two.

Advantages of using UART Arduino

  1. UART Arduino are pretty simple to operate. They are also well documented on the internet as people worldwide utilize the Arduino platform. Hence, you can find a lot of tutorials online on Arduino to help you grow your knowledge of the device and its uses.
  2. UART Arduino does not require a clock

Disadvantages of using UART Arduino

  1. Lower speed when compared to SPI and 12C
  2. Baud rates for every UART must be within 10 percent of each other; this prevents data loss.
  3. UART Arduino cannot utilize multiple masters like slaves and Arduino

What is Serial Transmission?

Arduino UART uses serial transmission to send and receive data, but what is serial transmission. Well, serial transmission is a method of transmitting data that transmits data one bit at a time. Hence UART Arduino sends information one bit at a time.

UART Communication Arduino

When computers transmit information to an Arduino, this occurs via USB (Universal Serial Bus). The USB signal is then converted into serial form, and then undergoes transmission to the UART. On receiving the data, the system will placed it inside a buffer (memory storage utilized to hold information temporarily). At this point, UART Arduino utilizes the three communication lines for efficient serial communication.

  • Just as the name suggests, the TX line (Transmission line) is good to efficiently send information to the recipient’s device. Hence, the sending device’s TX line should have a direct connection to the receiving device’s RX line.
  • In UART Arduino serial communication, these two lines send and receive information simultaneously; this means that UART Arduino can perform full-duplex communication.
  • UART transmits information asynchronously; this means that an external clock line does not drive the bits. But if there is no clock signal utilized to synchronize the output of bits that are being transmitted from the transmitting UART to the UART receiving the bits, how does the UART Arduino work then?


Instead of utilizing a clock, UART uses a start and a stop bit combined with the data packet undergoing transfer process. Here is how it works:

  • The start bit – Start bits show where data words begin. It is essential to synchronize the transmitter UART and the receiver UART.
  • The stop bit – Stop bits show when the last bit was sent. A stop bit can be one bit or multiple bits.
  • Data packet – They are usually nine to five bits in length. A data packet contains the information under transfer process. The information is in binary data bits form. The data packet is usually sandwiched between the start and the stop bits.
  • A parity bit – We mostly use it for error detection. It does the process via a single bit extra bit that one adds to the data under transmission. The parity bit tells the receiving UART whether the number of 1’s in the data under transmission is odd or even. The receiving UART can then assess whether or not the data is correct.

Baud Rate

Once a receiving UART Arduino device detects the start bit, it reads the incoming bits. However, for the reading process to be successful, the receiving UART device has to read the bits using a specific frequency, one that had been agreed upon initially by both devices. The agreed-upon reading frequency is known as baud rate. In simpler terms, the baud rate is the measure of data transfer speed.

The most commonly used baud rates when utilizing Arduino are:

  • 9600
  • 14400
  • 19200
  • And ultimately 115200

Now that we know how a UART Arduino works, let us look at the programming side that makes this device the brains of a project. The examples provided below are some of the most essential programs involved in UART Arduino programming:

Serial begin

The serial.begin command is useful in starting off serial communication. Its program looks like this:

  • Void setup(){

//To start off serial communication for an Uno R3


//To start serial communication for arduino Mega at port 3 you write



Using this command, you bound the UART only to accept one parameter; this is the baud rate. In this program, we have set the baud rate to be 14400.

The Uno board Arduino board has only one port for serial communication. Hence there is no need to specify the port number. However, other boards such as the Arduino mega board have more than one port. You, therefore, have to select the exact port that you wish to start serial communication.

Once you call upon the serial.begin, incoming bytes are then listened for, and once received, they are automatically stored inside a buffer.

Buffer overflow – when the process of receiving bytes is faster than the process of reading the, we call such a situation “buffer overflow.”


The serial.available command is placed inside an if statement to check if any information has been received. Once it identifies that data has been obtained, it returns the number of bytes that are available for reading. Suppose there are no bytes available for reading, the serial.available command returns false or 0.

The data undergoing checks is the data that has already arrived and is being stored inside a serial receive buffer.

Its program looks like this:

Void setup(){



Void loop(){

If (serial.available() > 0){

//do some task



How to read UART Arduino

If the buffer has information to read, the next step should ultimately be to read the available data. You can use the command for this job; this command reads bytes from the buffer.

The command returns the first incoming byte available. If there is no data in the buffer, this command returns -1.


The serial.readByte is applicable for reading multiple bytes. You, however, have to set the number of bytes to read, for example:

Serial.readbyte(buffer, length);

The serial byte command returns the exact number of characters available in a buffer. A zero means that no data (valid) is available.

The function stops once it has read the specified amount of bytes. It would help if you implemented serial.setTimeout to avoid unnecessary stalling if the program starts to wait for data that might never arrive.


What if you do not know how many bytes of data will be received? If such a case occurs, you utilize the serial.readByteUntil command, this command has an added argument known as “character.” The serial.readByteUntil reads the available data and only stops once it has read all the available data, when it times out, or when the UART receives a special character.

Its program look like this:

Serial.readByteUntil(character, buffer, length);

How to Print using UART Arduino


Besides just receiving data, an Arduino can send data to another device. We use the serial.print command to print information on a serial monitor as ASCII text that humans can read. Its program looks like this:

Void setup(){


Serial3.begin(14400); // for Arduino mega boards


Void loop(){

Serial.print(“hello world!);







The serial.println automatically adds a new line onto your program and returns at the text’s end.

Program example:

To achieve this feat, all you have to do is switch the serial.print used in the previous program and replace it with serial.println, for example, instead of typing in serial.print(“hello world!”); you type in serial.println(“Hello world!”);


If you wish to write serial numbers instead of ASCII characters you should implement the serial.write command. Here is an example of this program:






When you run this program it spells out “hello.”

Now that we have gone through how an Arduino works let us now look at the ft232r USB UART.

The FT232R

To get the concept of the ft232r USB UART drivers, you have first to understand the ft232r.

We can define the ft232r as a USB to serial interface for UART that implements an output through a clock generator. In addition to this, the ft232r uses synchronous and asynchronous bit modes taking the bang interface.

Now that we have that out of the way, we can now look at the ft232r UART driver.


If you are utilizing a windows operating system, you must have FT232R USB UART DRIVER to develop cool ft232r UART Arduino codes with your PC. So what exactly does the DRIVER do? Well, this software efficiently converts the language in use by the UART device into a language that your PC can understand. Your computer can hence decode any terms used in your Arduino program. You can also utilize the driver as a support element to any new functions that arise and all the USB protocols.

FT232R USB UART DRIVERS designed for windows devices are freely available. They are, however, pretty tricky to install, but no worries as we will take you through the installation process.

Different methods can be implemented in downloading the latest version of FT232R USB UART DRIVER suitable for your computer.

The first method: Update the FT232R USB UART DRIVER Version you have

If your FT232R USB UART DRIVER is old and not functioning correctly, this can be fixed via a simple software update to the newest version. We use FT232R USB UART to asynchronously carry out communication with other devices. However, achieving this feat requires a driver; this driver should help you update your FT232R USB UART DRIVER to the latest version. It prompts you, and all you need to do is monitor its instructions, and you are good. If this trick does not work, you might need to take manual steps in the installation of the driver.

The second method: Manual installation

For FT232R USB UART DRIVER, you will realize that the specific version good for windows is freely distributed but without an auto-installer. You hence have to manually install it into your device. Follow the following steps to install the drivers into your device.

  • Download the FT232R USB UART DRIVER from the internet. Ensure that you download this driver from a safe and secure provider.
  • After you have downloaded the drivers, head on to your control panel and start device manager. Right-click on exclamation mark you see (yellow in color), then select update driver software.
  • Extract the downloaded zip folder to get your FT232R USB UART DRIVER, and windows OS will then start the installation process. Once the installation process is done, you will have the latest FT232R USB UART DRIVER installed and you can start developing great Arduino projects.

The third method: manual installation of up-to-date latest driver from scratch

FT232R USB UART DRIVER installation from scratch can be pretty tedious and not to mention super tricky. Here are the steps to follow to achieve this feat:

  • Download the FT232R USB UART DRIVER
  • After downloading the driver, install into your device. To do so, follow the instructions provided as per installation wizard up to the very end.
  • Once you have completed the installation procedure, run the software and then complete the update.
  • Once you have extracted all the files, you will have to run the installer to enable you install UART DRIVER (FT232R USB).
  • On completing these steps, you must restart your computer to ensure that the FT232R USB UART DRIVER has been installed.

In summary form:

After you have downloaded the FT232R USB UART DRIVER, the next step is the installation process. You then install your serial port drive followed by the installation of the USB serial port drivers. You can run the software for the serial port. Lastly, restart the PC, this helps to confirm whether or not the driver has been installed.

Uninstall previous FT232R USB UART DRIVER

Once you have downloaded the latest FT232R USB UART DRIVER, uninstall the outdated version first before installation. You can then uninstall the earlier USB serial converter driver when you are done. Once you have taken care of this, you may install and utilize your ft232r USB UART without any issues.

It is crucial to remember that you cannot install FT232R USB UART DRIVER once you happen to delete it.

Official FTDI providers

FT232R USB UART DRIVER can be freely downloaded by visiting FTDI website. All you should do is search using the precise keywords, and the internet will do the rest for you.  

Arduino UART example

Arduino Uno Rev3

The Arduino Uno Rev3 is an incredible UART microcontroller board that is based on the ATmega328; this Arduino has the following specs:

  • 14 digital output/input pins
  • Six analog inputs
  • 16 MHz crystal oscillator
  • USB connection
  • A power jack
  • An ICSP header
  • A reset button

The Arduino Uno Rev3 is an incredible UART Arduino that you can utilize to test out the strength of UART technology.

The seeeduino v4.2

Another Arduino UART example is the seeeduino v4.2. For starters, this board is compatible with Arduino based on ATmga328P MCU. The seeeduino is pretty easy to use, and it is much more stable compared to other Arduino devices. You can also try out this board to take things up a notch.


Tech is evolving pretty fast; new inventions are coming in every day, all meant to improve our lives. Most of these inventions utilize Arduino boards as the brains of the project; this makes choosing the correct Arduino board pretty crucial. In this article, we have gone through all you need to know about UART Arduino, from its meaning down to Arduino UART examples. All this information will help you craft out a fantastic tech project. We hope that we have answered all the questions you might have had on the topic.