A Really Simple Arduino Oscilloscope Tutorial

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Arduino Oscilloscope

This Arduino oscilloscope is perfect if you need an oscilloscope right now, but all you have is an Arduino.

Update: There’s an even easier way to do this now. Check out my new article on how to build an Arduino oscilloscope with 7 lines of code.

I needed an oscilloscope to debug my Radar Arduino library.

The code worked perfectly when it was not in “Arduino library”-form. But when I modified it into a library, it just didn’t work at all.

Since the radar module (from https://www.xethru.com) was using the UART, I didn’t have any way of checking what was going on.

So I needed an oscilloscope to check if there was actually any action on the UART lines.

Tools needed:

Step 1: Upload Arduino Oscilloscope Code

First of all you need some code to read the analog value from the analog input pin A0. You can do this easily by using the analogRead() function.

Then you need to send this value over to your computer using the serial port. There are plenty of ways to do this. In the following code, the value is sent as two bytes with one 0xff byte in between.

This code reads an analog input and writes the value to the serial port. Upload the following code to your Arduino:

const int analogPin = A0;
 
void setup() {
  //Setup serial connection
  Serial.begin(9600); 
}
 
void loop() {
  //Read analog pin
  int val = analogRead(analogPin);

  //Write analog value to serial port:
  Serial.write( 0xff );                                                         
  Serial.write( (val >> 8) & 0xff );                                            
  Serial.write( val & 0xff );
}

This code is from https://gist.github.com/chrismeyersfsu/3270358#file-gistfile1-c

This is really all it takes on the Arduino side to make an Arduino oscilloscope. But to display the values, you need some code on your computer too.

arduino-oscilloscope

Step 2: Install Processing

You need something on your computer to receive the values that are sent from the Arduino and display them nicely. Processing is a simple programming environment to do this.

Download processing for free from their website: https://processing.org/

Then install it on your computer.

Step 3: Run Processing Code

Then, you’re ready to run the processing code. Copy and run the following code in processing to get a nice oscilloscope interface on your computer:

https://gist.github.com/chrismeyersfsu/3270419

arduino-oscilloscope-output

Step 4: Test Your Arduino Oscilloscope

Connect two jumper wires to your Arduino. One from the ground and one from the A0 analog input.

You should now be able to use these wires to measure things and see the measurement on your computer.

Viola! You’ve just created a super simple Arduino oscilloscope.

Oscilloscopes are actually very easy to use, once you learn a few basic things: Learn how to use an oscilloscope.

Return to What is Arduino?

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29 thoughts on “A Really Simple Arduino Oscilloscope Tutorial”

  2. Cool little project, thanks Oyvind! A few thoughts…
    One can get good accuracy if rather than sampling from within an indeterminately-sized loop, one instead bases the sample timing on some kind of reliably consistent clock. While you may succeed using one of the PWM outputs to trigger an external interrupt as your timer, I would say the “right way” to do this is to use the Arduino’s Timer Interrupts. Or, for those who really want serious high accuracy, a dedicated real-time clock (RTC), should be used. The DS3231 chip, can send clock ticks as fast as 400kHz over its serial I2C interface, thus your oscilloscope could sample frequencies as high as 200kHz. Not bad.
    As long as sample timing is *consistent*, it’ll be accurate enough to do some fun things with, for example, an audio signal as input. Well, at least in the time domain…
    Has anyone tried running an FFT on the Arduino??! :-)
    Cheers.

    Reply

  4. Thank you for the great project. I am having some difficulty since I have no idea about processing software , I have followed all the steps given above but the processing software does not show any wave instead on arduino serial monitor window there are continuous stream of various symbols.
    So I will be thankful if someone could help me.

    Reply

    • Hi,

      The continouos stream of symbols on the serial monitor is a good sign. At least something is coming from the Arduino.

      Could it be that no wave is showing because there are no wave to show? What are you measuring?

      Cheers!
      Oyvind

      Reply

  5. Is there a way that you could read 3 or 4 signals at the same time? Each one above the other and from 0 to 18 volts? This way you could check 4 signals on a car engine and see if they were firing in the correct sequence? The signals only need to relate to one another.
    Thanks

    Reply

    • I haven’t used this in over a year, but it worked when I tried it. I suggest you contact the developer from the link in the article, and he should be able to help you out.

      Best,
      Oyvind

      Reply

  10. Hello,
    I have the same problem as “arsalan”.
    My Arduino is sending data, which i can see on the serial monitor.
    The “oscilloscope” sadly does not show anything, not even if I test it with two wires as you suggest above.
    Do you have any idea how i could solve this problem?

    Best regards
    Florian

    Reply

    • Hey,
      It’s been a while since I’ve tried this code, so I am not sure. In the new version of the Arduino IDE there is a data-plotter included. It’s much easier to use and doesn’t require the processing code. I’ll write an article about this soon.

      Best,
      Oyvind

      Reply

      • Hi,
        thank you for that response! After some time of trying to get it work, I found out about the Serial plotter, really great for fast signal checks.

        Best Regards
        Florian

        Reply

  11. I just got this running. Very nice!

    The Processing sketch was coming up with nothing, because the following line was not picking up the serial port on Windows:

    port = new Serial(this, Serial.list()[0], 9600);

    Changed it to the serial port for my Arduino, and it works great.

    port = new Serial(this, “COM17”, 9600);

    Reply

  12. Another trick: change the setup loop as follows, and you can hook the wire from A0 to (one at a time) pins 9, 10 and 11 to see the PWM waveforms generated by the microcontroller for different levels.

    void setup() {
    //Setup serial connection
    Serial.begin(9600);
    // Set up PWM output on pins 9,10 and 11 for different levels.
    // You do it here because once it’s set up, it keeps running.
    // You don’t need it in the main loop so it doesn’t interfere
    // with the measurements.
    // Once it’s running, attached the wire from A0 to each pin to
    // see the square waveform generated by each value – 100, 150, 200.
    pinMode(10, OUTPUT);
    pinMode(11, OUTPUT);
    pinMode(9, OUTPUT);
    analogWrite(9,100);
    analogWrite(10,150);
    analogWrite(11,200);
    }

    Reply

  13. Thanks to all that are contributing to this.
    My question is what do you have running on the PC that does the display?
    I have it running but the lines are all jammed together.
    I am trying to get something that looks like a simple sine wave. Any frequency, any voltage.
    And without digging into the code, are there any keys that will do “stuff” ?
    thanks

    Reply

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