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ESP32 - Serial Plotter

We are going to learn how to:

  • How to use Serial Plotter with ESP32.

Video Tutorial

you can watch this video tutorial

Hardware Required

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable

About Serial Plotter

Serial Plotter is one of the tools in Arduino IDE. ESP32 can read the temperature, humidity or any kind of sensor data, and send it to Serial Plotter. Serial Plotter receives data from ESP32 and visualizes data as waveforms. Serial Plotter can visualize not only single but also multiple sensor data in the same graph.

Data is exchanged between Serial Plotter and ESP32 via USB cable, which is also used to upload the code to ESP32. Therefore, To use Serial Plotter, we MUST connect ESP32 and PC via this cable.

Serial Plotter includes a selection box to select the serial baud rate and a graph:

  • X-axis: represent the time. It has 500 points. The time between each point is the time between two consecutive Serial.println() function calls. This time is usually equal to the time of loop() function.
  • Y-axis: represents the values received from ESP32. The Y-axis automatically adjusts itself as the value increases or decreases.

How To Open Serial Plotter

On Arduino IDE, Go to Tools >> Serial Plotter

Arduino IDE Upload Code

Plotting of Single Line in Graph

To print a single graph, we just need to send the data and terminate it by “\r\n” character.

In detail, we just need to use Serial.println() function 

 Serial.println(variable);

※ NOTE THAT:

Serial.println() automatically appends “\r\n” characters after data.

Example Code

In this example, we will send the “esp32io.com” from ESP32 to Serial Monitor every second

Copy

void setup() {
  Serial.begin(9600); 
}

void loop() {
  int y1 = analogRead(2);

  Serial.println(y1);

  delay(100);
}

Quick Steps

  • power up your board
  • Open Arduino IDE
  • Select the right board
  • Select the right port
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to ESP32
  • Open Serial Plotter on Arduino IDE
  • Select baurate 9600
  • See graph on Serial Plotter
    • Arduino IDE Upload Code

Plotting of Multiple Lines in Graph

When we want to plot multiple variables, we need to separate variables from each other by “\t” or " " character. The last value MUST be terminated by “\r\n” characters.

In detail:

  • The first variable 
    Serial.print(variable_first);
  • The middle variables 
    Serial.print("\t"); // or Serial.print(" ")
Serial.println(variable_last);
  • The last variable 
    Serial.print("\t"); // or Serial.print(" ")
Serial.print("\t"); // or Serial.print(" ")

Example Code

This example reads the value from 4 analog input pins and plots them on Serial Plotter

Multiple Graph:

Copy

void setup() {
  Serial.begin(9600); 
}

void loop() {
  int y1 = analogRead(2);
  int y2 = analogRead(4);
  int y3 = analogRead(5);
  int y4 = analogRead(18);

  Serial.print(y1);
  Serial.print(" ");       // a space ' ' or  tab '\t' character is printed between the two values.
  Serial.print(y2);
  Serial.print('\t');      // a space ' ' or  tab '\t' character is printed between the two values.
  Serial.print(y3);
  Serial.print(" ");       // a space ' ' or  tab '\t' character is printed between the two values.
  Serial.println(y4);      // the last value is followed by a carriage return and a newline characters.

  delay(100);
}
Arduino IDE Upload Code

Example of 3 Sine Waveforms

Multiple Sine Waveform Graph:


void setup() {
  Serial.begin(9600);
}

void loop() {
  for(int i = 0; i < 360; i += 5) {
    float y1 = 1 * sin(i * M_PI / 180);
    float y2 = 2 * sin((i + 90)* M_PI / 180);
    float y3 = 5 * sin((i + 180)* M_PI / 180);

    Serial.print(y1);
    Serial.print("\t");           // a space ' ' or  tab '\t' character is printed between the two values.
    Serial.print(y2);
    Serial.print("\t");           // a space ' ' or  tab '\t' character is printed between the two values.
    Serial.println(y3);           // the last value is followed by a carriage return and a newline characters.

    delay(100);
  }
}
Arduino IDE Upload Code

Book Tutorial

We are considering to make the book tutorials. If you think the book tutorials are essential, you can download it. download book

See Also

References

※ NOTE THAT:

Some components works on 3.3v and others works on 5v!

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السلام عليكم و رحمة الله و بركاته
مع تمنياتنا بالنجاح و التوفيق