Arduino Debugger - Getting Started

Introduction: Arduino Debugger - Getting Started

About: I'm currently a graduate student at CU Boulder researching how to help people with debugging their embedded systems projects (Arduino, MakeCode, micro:bit, etc.). I love programming and teaching others about…

Are you learning to program an Arduino microcontroller, but wish the Arduino IDE provided some tools for debugging? Follow this Instructable to learn how to use the ArduinoDebugger, a C++ library, to debug your Arduino sketches.

The ArduinoDebugger provides the following tools:

  • Variable tracking : view and update variable values at runtime
  • Hardware pin tracking : view and update the state of hardware pins at runtime
  • Breakpoints : pause a running program to check on variables and hardware pins.
  • Print Statements : view variables and hardware pins as they change

To try out the ArduinoDebugger, follow the next two steps to include the custom library and load the example program.

This material is based upon work supported by the National Science Foundation under Award #1742081. The project page can be found here.

This project (formerly known as PinStatus) was developed in the Craft Tech Lab at the University of Colorado Boulder and co-created with Chris Hill.


Arduino Microcontroller - Ex. Adafruit Circuit Playground or Arduino Uno

Step 1: Importing the ArduinoDebugger Library

In order to use the ArduinoDebugger library you'll need to first download the library and then add it to your Arduino IDE.

  1. Download the library

The ArduinoDebugger library can be downloaded from a Google Drive Folder here:

Make sure to note where you save the zipped directory (

2. Add the .zip library

Once downloaded, open your Arduino IDE and navigate to the "Sketch > Include Library > Add .ZIP Library". You can now include the ArduinoDebugger library into your Arduino sketches, but you may need to restart the IDE to access the provided examples.

Step 2: Example Program

An example program can found under "File > Examples > ArduinoDebugger > 1_Basic_Setup". The code for the example sketch is also provided at the bottom of this step. Upload the example program to your chosen Arduino microcontroller and then open up the Arduino IDE's Serial Monitor.

Via the Serial Monitor, you'll be able to access the breakpoint's menu which will give you control of the program's variables (counter, message) and the board's hardware pins. Try updating a variables value or changing a hardware pin's state (for example Digital Pin 13 is often an onboard LED; try setting it to HIGH/LOW).

#include <ArduinoDebugger.h>
//the intialize method determines if the debugger uses 8-bit or 32-bit registers
//and whether or not it can handle floats.
// intialize(usingFloats, is8Bit);
// Floats are generally not recommended because they use a lot of memory space.
Debugger debugger = ArduinoDebugger::initialize(NO_FLOATS, BITS_8);//Adafruit Circuit Playground Classic
//Debugger debugger = ArduinoDebugger::initialize(NO_FLOATS, BITS_32);//Adafruit Circuit Playground Express
byte d_pins[] = {LED_BUILTIN, 10, 9};//Subset of digital pins
byte a_pins[] = {A0, A1};//Subset of analog pins
byte counter = 0;
void setup() {
while(!Serial) {}
debugger.setSubsetPins(d_pins, 3, a_pins, 2);//Set subset of pins
debugger.add(&counter, BYTE, "counter");//Add to variable watch
void loop() {
if(counter %2 == 0)
digitalWrite(LED_BUILTIN, HIGH);
debugger.print("LED HIGH");//Displays information, no pausing
//debugger.breakpoint("LED HIGH");//Pauses & displays menu for updating variables & hardware pins
digitalWrite(LED_BUILTIN, LOW);
debugger.print("LED LOW");//Displays information, no pausing
//debugger.breakpoint("LED LOW");//Pauses & displays menu for updating variables & hardware pins

Step 3: Breakpoints Vs Repeats Vs Prints

The ArduinoDebugger provides three ways to access debugging information (breakpoints, repeats, and prints). They all will provide information on variables and hardware pins but in slightly different ways.

Breakpoint: Handy for changing values while the program is running

A breakpoint pauses a running Arduino program and provides a menu via the Serial Monitor. With the menu, a programmer can select to:

1) View Variables:

Here you can see what variables are currently set to and even update them to new values. To use this feature, you'll need to add your variables to the debugger, using the add() method.

2) View Hardware Pins:

Here you can see what state digital pins are set to and the current value read off of the boards analog pins. You can also set the digital pins to either HIGH or LOW

debugger.breakpoint();//Use when you only want 1 breakpoint

//The string identifiers which breakpoint the program has stopped at

Repeat: Great for printing out a series of data and then pausing for you to read it

A call to repeat() will display the current state of hardware pins and variable values. After being called X number of times, the repeat() will pause the running program so the programmer can read through the system information presented in the Serial Monitor.

debugger.repeat(5);//After being called 5 times, repeat() will pause the running program

Print: Display debugging information WITHOUT pausing the program

The print() method displays all the same information repeat() does, but without pausing the program. This is a handy way to throw in debugging information without worrying about pausing/continuing the Arduino Program.


Step 4: Turning Off the Debugger

What happens when you finish debugging? You have two choices. You can either delete the code you wrote to use the debugger OR you can simply turn the debugger off until you need it again. We recommended going with the second option until you have completely finished your project. To turn off/on the ArduinoDebugger, make a call to the turnOff() method. This method ensures debugging information isn't displayed to the Serial Monitor. If you later need to do some more debugging, delete the call to the turnOff() method.

debugger.turnOff();//Debugging information won't be displayed

Step 5: Further Details

The ArduinoDebugger library provides a lot more configurations and options then are covered in this short instructable. To learn more about what the ArduinoDebugger can do, check out the full documentation here:

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    Question 1 year ago

    Awesome tool. I am trying to use it with FLOATS but still get the message about setting floats to true when I display data. The library still seems to call the Debugger class method for displaying variables instead of the DebuggerF class. I can't find what I'm doing wrong.


    Answer 1 year ago

    Sorry for the late response!
    I'll take a look at the library and see if I can find the issue. I haven't been actively developing this library in a while, so it may take a bit to find the issue.


    Reply 1 year ago

    Great job. I've written developer tools myself. Admirable project. Unfortunately, the Serial Monitor seems to have problems in VSCode. The base Arduino IDE works fine. Apparently the interface doesn't recognize ClearScreen and just keeps going. Oh, I also found an issue in the repeat function with a print command formed improperly resulting in ALL_DATA being printed instead of the specific request.


    Reply 1 year ago

    Thanks for the deep dive into the code! I actually never tested the library with VS Code. The only terminal application I have tested with was Putty, when I was first testing the use of terminal commands. But since the Arduino IDE doesn't support clear screen, I didn't go very far down that path of terminal optimization.

    Also, thanks for finding the issue with ALL_DATA. Even though I still consider this library a work-in-progress / proof-of-concept, the irony doesn't escape that my debugging tool is still itself quite buggy! Now that summer has begone, I hope to now find the time to fix these underlying issues and have a more robust debugging tool.


    Reply 1 year ago

    I found it quite useful and almost identical to the functionality I was going to build myself into my instructable I'm working on. Your library does everything I needed. So, of course I will share with you what I find and anything I fixed or added.
    Hmmm. The continual scrolling before VSCode broke altogether with it's new update was annoying. I went back to my latest Arduino IDE and that's where I discovered the clear screen DOES work! Microsoft whines about the USB interface in the Arduino IDE isn't using the native code properly and needs to be fixed for VSCode to work properly although it uploads code.
    You have built a wonderfully useful foundation for me to tinker with. So far, I only found the one thing and I've been crawling around under the hood so to speak.


    2 years ago

    Uh! That sounds nice!
    How many times have i added a little Pin-Toggle to my sketches to figure out if something works or not...
    I havent checked it out, but i would really like to have a PinToggle and not only PinSet ;)


    Reply 2 years ago

    By PinToggle do you mean changing the pinMode() or simply setting a pin High then Low? The library does allow you to set a digital pin's state at runtime via the breakpoint() method. Unfortunately we don't currently support checking or changing a pin's mode (Input vs Output)