Arduino - Serial Monitor
Hardware Required
Or you can buy the following kits:
| 1 | × | DIYables STEM V3 Starter Kit (Arduino included) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables .
Additionally, some links direct to products from our own brand, DIYables .
About Serial Monitor
Serial Monitor is one of the tools in Arduino IDE. It is used for two purposes:
- Arduino → PC: Receives data from Arduino and display data on screen. This is usually used for debugging and monitoring
- PC → Arduino: Sends data (command) from PC to Arduino.
Data is exchanged between Serial Monitor and Arduino via USB cable, which is also used to upload the code to Arduino. Therefore, To use Serial Monitor, we MUST connect Arduino and PC via this cable.
How To Use Serial Monitor
Open Serial Monitor
Click the Serial Monitor icon
Items on Serial Monitor
- Output console: display data received from Arduino.
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- Autoscroll checkbox: option to select between automatically scroll and not scroll.
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- Show timestamp checkbox: option to show timestamp prior to data displayed on Serial Monitor.
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- Clear output button: clear all text on the output console.
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- Baud rate selection: select communication speed (baud rate) between Arduino and PC. This value MUST be the same as the value used in Arduino code (in Serial.begin() function).
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
※ NOTE THAT:
When we select baud rate (even the value is not changed), Arduino is reset. Therefore, this is one way to reset Arduino.
- Textbox: user can type characters to send to Arduino
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- Ending selection: select the ending characters appended to data sent to Arduino. Selection includes:
- No line ending: append nothing
- Newline: append newline (LF, or '\n') character
- Carriage return: append carriage return (CR, or '\r') character
- Both NL and CR: append both newline and carriage return (CRLF, or '\r\n') characters
- Send button: when the button is pressed, Serial Monitor sends data in textbox plus the ending characters to Arduino
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
Arduino To PC
To send data from Arduino to PC, we need to use the following Arduino code:
- Set baud rate and begin Serial port by using Serial.begin() function
Serial.begin(baudrate);
- Send data to Serial Monitor using one of the following functions: Serial.print(), Serial.println(), Serial.write(). For example, send “Hello World!” to Serial Monitor
Serial.println("Hello World!");
Example Use
In this example, we will send the “ArduinoGetStarted.com” from Arduino to Serial Monitor every second
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-serial-monitor
*/
void setup() {
Serial.begin(9600);
}
void loop() {
Serial.println("ArduinoGetStarted.com");
delay(1000);
}
Quick Steps
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Open Serial Monitor
- Select baurate 9600
- See the output on Serial Monitor
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
ArduinoGetStarted.com
ArduinoGetStarted.com
ArduinoGetStarted.com
ArduinoGetStarted.com
- Try changing Serial.println() function to Serial.print() function
PC To Arduino
How to send data from PC to Aduino and read it on Arduino
You will type text on Serial Monitor and then click Send button.
Arduino reads data and process it. To read data, we need to use the following Arduino code:
- Set baud rate and begin Serial port
Serial.begin(baudrate);
- Check whether data is available or not
if(Serial.available())
{
// TODO
}
- Read data from Serial port using one of the following functions: Serial.read(), Serial.readBytes(), Serial.readBytesUntil(), Serial.readString(), Serial.readStringUntil(). For example:
String data = Serial.readStringUntil("\r\n");
Example Use
In this example, we will send the commands from Serial Monitor to Arduino to turn on/off a built-in LED. The commands include:
- “ON”: turn on LED
- “OFF”: turn off LED
How Arduino can receive a complete command? For example, when we send “OFF” command, how Arduino can know the command is “O”, “OF” or “OFF”?
⇒ When sending a command, we will append a newline character ('\n') by selecting “newline” option on Serial Monitor. Arduino will read data until it meets the newline character. In this case, the newline character is called delimiter.
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-serial-monitor
*/
void setup() {
Serial.begin(9600);
pinMode(LED_BUILTIN, OUTPUT); // set the digital pin as output:
}
void loop() {
if(Serial.available()) // if there is data comming
{
String command = Serial.readStringUntil('\n'); // read string until meet newline character
if(command == "ON")
{
digitalWrite(LED_BUILTIN, HIGH); // turn on LED
Serial.println("LED is turned ON"); // send action to Serial Monitor
}
else
if(command == "OFF")
{
digitalWrite(LED_BUILTIN, LOW); // turn off LED
Serial.println("LED is turned OFF"); // send action to Serial Monitor
}
}
}
Quick Steps
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to Arduino
- Open Serial Monitor
- Select baurate 9600 and newline option
- Type “ON” or “OFF” and click Send button
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
- See the built-in LED's state on Arduino board. We will see LED's state is ON or OFF, respectively.
- We also see LED's state on Serial Monitor
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
LED is turned ON
- Try typing “ON” or “OFF” command some times.
Video Tutorial
We are considering to make the video tutorials. If you think the video tutorials are essential, please subscribe to our YouTube channel to give us motivation for making the videos.