Arduino Serial Output

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Overview

module url N/A
git repository https://bitbucket.org/arrizza-public/arduino-serial-output
git command git clone git@bitbucket.org:arrizza-public/arduino-serial-output.git
verification report https://arrizza.com/web-ver/arduino-serial-output-report.html
version info
OS Language #Runs Last Run Cov%
macOS 14.5 Python 3.10 - - -
macOS 15.5 Python 3.12 11 2025-08-06 -
macOS 15.6 Python 3.12 36 2026-07-14 0%
macOS 26.6 Python 3.12 6 2026-08-11 0%
macOS 26.6.1 Python 3.12 9 2026-09-04 0%
win32 Windows 11 Python 3.12 47 2026-09-05 0%
Ubuntu 20.04 focal Python 3.10 - - -
Ubuntu 22.04 jammy Python 3.10 - - -
Ubuntu 24.04 noble Python 3.10 4 2025-04-14 -
Ubuntu 24.04 noble Python 3.12 65 2026-09-05 0%

Summary

Prints text to the Arduino Serial Port.

This is a simple Arduino App that blinks the LED and also outputs some data on the serial port. To see that output you need to set up a terminal emulator like Putty or screen and configure it correctly (115200, 8n1).

Setup

This also sets up the serial port at the 115200 baud rate. A baud is 1 bit per second, so 115200 baud rate is 115,200 bits per second. There are other bits that may get sent for each byte (a start bit, a parity bit and a stop bit).

It also sends a message "setup" to the serial port.

Serial.begin(115200);
Serial.println("setup");

Serial.begin() is a function that sets up the serial port to the given baud rate, in this case 115,200 bps.

The Serial.println() is a function that prints the parameter given to it, in this case the word " setup" and follows it with a newline.

A newline is a carriage return or a linefeed or both, depending on which Operating System you are on. This is equivalent to pressing the Enter key on the keyboard - it puts a new line in the output. It is sometimes abbreviated as "nl" and sometimes it is referred to as "\n" (this is because in many languages "\n" represents a newline sequence).

A carriage return, sometimes abbreviated as "cr", is a single character with hex value 0x0D.

A linefeed, sometimes abbreviated as "lf", is a single character with hex value 0x0A. This is used for most Linux or Unix based systems and for the Arduino.

On Windows, a newline is a two character combination 0x0D 0x0A (carriage return/line feed).

Main Loop

The main loop is similar to "Main Loop" in Arduino LED Blink. It also prints a "1" and "0" to the serial port every second.

Serial.print("1");

Serial.print("0");

The Serial.print() is a function that is identical to the Serial.println() except it does NOT print the newline character. Because of the newline is missing, the "1" and "0" will be side-by-side on the terminal output.

   setup
   101010101010

It will continue writing the "10" sequence until you unplug the USB cable.

Notes

  • You must have the terminal emulator (e.g. Putty) configured correctly.
    • for CLion, see "Setup Serial Monitor in CLion" in Arduino Setup
    • for others, see "Setup putty or screen" in Arduino Setup
    • Don't forget. To upload a new version to the Arduino, you have to disconnect the terminal emulator. And that re-plugging in the terminal emulator will reboot your Arduino.
  • You should see a "1" when the LED is blinking quickly, and you should see a "0" when the LED is off.
  • Try changing the text inside the Serial.println() or Serial.print() statements. You should see whatever you typed in there, showing up on your terminal emulator.
  • Try changing the Serial.print() to Serial.println(). You should see a newline after each 1 and 0, something like:
 0
 1
 0
 1
 0
# ... etc ...

- John Arrizza