ESP32 - Serial Plotter

This tutorial instructs you how to use Serial Plotter on Arduino IDE with ESP32

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
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Introduction to Serial Plotter

The Serial Plotter is a tool on Arduino IDE the can receive data from ESP32 via Serial and plot it on a graph. The Serial Plotter can plot multiple sensor's data in the same screen.

To receive the data from ESP32, It needs to use a micro USB cable between ESP32 and PC

Serial Plotter is composed of two components:

  • a selection box: used to select the serial baudrate
  • a graph:: a screen that shows the visualized data
    • X-axis: presents the time. It has 500 points. The time between each point is the time between two consecutive Serial.println() function calls.
    • Y-axis: presents the data values received from ESP32. The Y-axis automatically scales when the data's value increases or decreases.

How To Open Serial Plotter

On Arduino IDE, Navigate to Tools Serial Plotter

how to open serial plotter

How to plot a Single Line on Graph

To plot a single line on graph, we just need to send the data terminated by “\r\n” character. We can use Serial.println() function

Serial.println(variable);

※ NOTE THAT:

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

Example Code

The below ESP32 example code reads the value of an analog input pin and send it to Serial Plotter

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-serial-plotter */ void setup() { Serial.begin(9600); } void loop() { int variable_1 = analogRead(A0); Serial.println(variable_1); delay(100); }

Quick Instructions

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
  • Copy the above code and paste it to Arduino IDE.
  • Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
  • Open Serial Plotter
  • Select baurate 9600
  • See graph on Serial Plotter
  • serial plotter example single line

How to plot multiple lines on Graph

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.print(variable_nth);
  • The last variable
Serial.print("\t"); // or Serial.print(" ") Serial.println(variable_last);

Example Code

The below ESP32 example code reads the value from 4 analog input pins and sends them to Serial Plotter

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-serial-plotter */ void setup() { Serial.begin(9600); } void loop() { int variable_1 = analogRead(A0); int variable_2 = analogRead(A1); int variable_3 = analogRead(A2); int variable_4 = analogRead(A3); Serial.print(variable_1); Serial.print(" "); // a tab '\t' or space ' ' character is printed between the two values. Serial.print(variable_2); Serial.print(" "); // a tab '\t' or space ' ' character is printed between the two values. Serial.print(variable_3); Serial.print(" "); // a tab '\t' or space ' ' character is printed between the two values. Serial.println(variable_4); // the last value is terminated by a carriage return and a newline characters. delay(100); }

The result on Serial Monitor:

serial plotter multiple lines

Example of 3 Sine Waveforms

The below ESP32 example code print three sine waveform's value to Serial Plotter

/* * This ESP32 code is created by esp32io.com * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-serial-plotter */ void setup() { Serial.begin(9600); } void loop() { for (int i = 0; i < 360; i += 5) { float sine_1 = 1 * sin(i * M_PI / 180); float sine_2 = 2 * sin((i + 90) * M_PI / 180); float sine_3 = 5 * sin((i + 180) * M_PI / 180); Serial.print(sine_1); Serial.print("\t"); // a tab '\t' or space ' ' character is printed between the two values. Serial.print(sine_2); Serial.print("\t"); // a tab '\t' or space ' ' character is printed between the two values. Serial.println(sine_3); // the last value is terminated by a carriage return and a newline characters. delay(100); } }

The result on Serial Plotter:

serial plotter sine wave

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