Raspberry Pi Pico Oscilloscope

As you dive deeper into the world of electronics, a good oscilloscope quickly is an indispensable tool. However, for many use cases where you’re debugging low voltage, low speed circuits, that expensive oscilloscope is using only a fraction of its capabilities. As a minimalist alternative for these use cases [fhdm-dev] created Scoppy, a combination of firmware for the Raspberry Pi Pico and an Android app to create a functional oscilloscope.

As you would expect, the specifications are rather limited, capturing a maximum of 100 kpts at a speed of 500 kS/s shared between the two channels. Without some additional front end circuitry to protect the Pico, the input voltage is limited to 0-3.3 V. Neither the app nor the firmware is open source, and getting access to the second channel and removing ads requires a ~$3 in-app purchase. Even so, we can still think of plenty of practical uses for a ~$7 oscilloscope. If you do decide to add some front-end circuitry to change to voltage range, you can set them in the app, and switch between them by pulling certain GPIO pins high or low. The app has most of the basic oscilloscope features covered, continuous and single shot capture, adjustable trigger settings and a scalable waveform display.

Simple, cheap oscilloscopes like these have their place, but you start to understand why the “real” ones are so expensive when you see what goes into developing a high performance oscilloscope.

47 thoughts on “Raspberry Pi Pico Oscilloscope

    1. We thought it was moderately neat, but it is a closed-source product that _does_ cost money. That is all mentioned in the article.

      Nonetheless, just to be clear, this is not an advertisement or an endorsement. We didn’t get paid, and we’ve got no skin in the game. One of our writers thought it was neat.

      1. I’m a bit late catching up on my HaD reading backlog but wanted to add my +1

        It is neat.
        I’m happy this is on HaD.

        I don’t remember where it said HaD had to be limited to open-source projects.

        For $7 this can be cheap, useful and a lot of work seem to have gone into the app.

        If the work is so simple and trivial as to be given out for free then it should be simple and trivial to rewrite.
        Something about horses and oral checkups.

          1. _You_ get it right. It’s the want of money — meaning the lack thereof in ye olde English translation.

            The idea was that peoples’ poverty drove them to crime, rather than them being inherently bad. It was a revolutionary, and very kind and progressive, standpoint at a time when people were being stoned and enslaved.

          2. Absolutely right, sadly our Socialist friend here doesn’t understand how the world works. The only reason we have open source software in abundance is because uber-wealthy companies have been able to pay software developers very high salaries and at times also afford them time to work on their pet projects. If it weren’t for all the cash the industry is awash with, there would be no open source software. IE the developers of open source software are all very well paid people in the industry. Don’t believe me? Take a look and see how much open source software is being developed in third world countries where there is no money and no such jobs. As always unfortunately, Socialists can’t learn from history and live in the real world.

          3. Wait, a company? An organisation that has a pool of wealth with a collective of differently skilled workers to co-operate on a common task??? Sounds communist to me.

            Now if we throw out this pseudo-capitalistic socialistic contraption and recognise the true autonomy of the individual, obviously you just need one skilled guy who can make your thing over the years it takes to mine the ores by hand and render them into your preferred unique and exclusive product, and pay him a kings ransom for the task.

            Companies indeed, leave collectivism to the ants.


    2. Plus 1 garbage. Just pipe the output from the ADC to the serial line of an Arduino will give you about the same. Then just pick the method of graph you feel like. Still has the same problem of no voltage protection etc and the relatively low sampling rate. And with minimal hardware you could probably use a digital input and do some Nyquist math to try to reconstruct a waveform

  1. there are so many of these now. i periodically get tempted by them but the tiny bandwidth and voltage ranges always turn me off. i don’t think i could use it for a single project. i love using my scope because i can zoom in and measure a 2us rise time – i can use it to directly observe and confirm things that i’d only worked out through my (poor) understanding of analog circuits. i certainly don’t want to be playing games with voltage dividers just to measure a 10V signal. i’m really impressed with how awesome my siglent 1102 is, especially for its price…but i can’t find much use for a scope much lower than that. i had a cheaper handheld scope before it, and i don’t think i got valuable information out of it even once, and it was miles ahead of this device.

    i feel like this is comparable to the digitally-controlled analog interconnect breadboard from a couple days ago. if you put the test equipment first, you can devise a project to take advantage of it. but if you put the project first, it’s gonna be hard to get either of these tools to do anything useful for you.

    1. It’s not just the limited voltage range, but the fact that you will probably destroy the device if you exceed it. A properly designed input stage will clamp the voltage and protect the internal components

  2. “Neither the app or the firmware is open-source”. I stopped reading there. Why this commercial projectsurfing on the “last Raspberry Pi chip” has a gthub repository at all ?

  3. This looks fairly nice, but with its limitations and the low price of very competent ‘scopes these days, both standalone and USB based, one would outgrow this very rapidly. The 3.3 V input range would be the most limiting factor.

  4. Someone has taken the time to create an app, which you can use for free. Or you can choose not to. It has adverts, big deal, let the author make a few pennies for their efforts. And no source code? So what, it’s a tool, not more free software as people have come to expect far too much. Show me another walk of life where highly skilled and/or qualified people are expected to work for nothing. So many forum posts instantly criticise. Maybe try to look for the positives occasionally?

    1. Not so much people complaining that the app has adds or the firmware isn’t open source just that it was a waste of their time on hackaday and that the content doesn’t belong on this site.

    2. You are confusing free (as in no cash) with open source. Not the same. Without source code, it’s useless or will be very soon. With source code, you can still sell it. Although I wouldn’t be interested for all the reasons listed above.

      Keeping the source to yourself won’t stop people copying the application. Although your point about highly skilled people writing code is fair, the authors are relying on hundreds of others to make their code work. And all if that code is open source.

    3. i expect any of tools to be accessible enough that I can adapt then to fit your needs. If not, it has to have some serious feature that no open-source accessible tool brings. Which obviously this thing fails at.
      If it´s all good for you, fine, go ahead, buy it: you know the price, the limitations of it, it´s all good for you.
      But this website is not particularly about promoting products, but about emphasizing what can be reach at hacker/hobbyist and sharing the knowledge.

      And this product just have nothing to do here. Especially when it misuses githubm using it a marketing support !

    1. There are all sorts of projects posted here that have no direct utility to me, yet I still find value in reading about them.

      I agree that this site is about learning and sharing. But it’s also about inspiration.

      I might just be inspired to build my own version of the project in question, and do it my own way. I don’t need source code for that.

      No disrespect intended, but why are people in this forum so up tight? People bitch about spelling errors in the articles, talk trash about others for using an Arduino, and pronounce–as self-appointed judges– “That’s not a hack!” Now it’s a problem if a project includes closed source code?

      In a perfect world everyone’s typing/spelling would be flawless. Nobody would use an Arduino for tasks a 555 could do. All hack postings would display genuine invention and creation. People wouldn’t destroy valuable antiques to build “steampunk” stuff. Demo videos would be filmed in landscape mode with a steady hand and the background music would not suck. And yes, every byte of code would be open source.

      Or… we can just be happy with a free forum that spreads interesting ideas, and you can pick, choose, and walk away with those tidbits of information that are of value to you.

      1. I think that’s just the personality type of the people who typically do this hobby. We tend to be varying levels of perfectionists and have strong ethical ties to open source. If that’s not for you, there are plenty of companies that will take your money and provide similar or better products. They just don’t usually get articles written about them.

      2. Agreed, I see it as a proof of concept, a product designed with cheap hardware. But that’s just me, I’ll buy cheap devices at the dollar store just to tear them apart and debug the i/o while considering what else the parts can be used for.

  5. This project seems to be mostly useless and underpowered compared to other options. If you look at the buck50 which uses a bluepill as a logic analyser with 8 channels at 6+MHz and a dual channel 1MHz oscilloscope then this here is useless and costs more for the board and you have to pay for the app, compared to buck50 which is open source. It could probably be adapted for more powerful microcontrollers like the blackpill which is supposed to have 2.4MSPS on the ADC and could maybe have a higher frequency logic analyser.

    At least with the buck50 it could probably be adapted to different use cases and is much more useful than this here, with double the sample rate and a logic analyser with a list of other features, if interested check out this link:

  6. For a hobbyist, the first thing you would do with an oscilloscope is look at an I2C or SPI waveform to see what’s going on.

    This unit is marginal for a low-speed I2C signal, and useless for high-speed I2C and SPI.

    It’s like you have to struggle to find examples where this tool would be useful. If you don’t have the 200 – 400 bucks to buy a real scope, that’s a hurdle, but this device isn’t a solution.

  7. define good

    I got a 20Mhz hybrid scope for free, kicks the shit out of this thing … one is better off getting a mid to high range scope for near free from the 80’s than most trash from today

    if you want trash from today deal with the DSO series, they are not bad for the fact they come in partial kit form for less than 20 bucks (thought the screen is too small)

  8. You’ve not only missed my point, I think you’ve made some unwarranted assumptions.

    I’ve run Linux servers for two decades at work, I’ve run Linux on all my home computers for more than 10 years. I’ve worked all manner of projects including large ones (>2 years of work) using open source tools exclusively. I prefer, advocate, and have (as you put it) “strong ethical ties to open-source.”

    I also tend to be a perfectionist, so I understand that point of view, too. There are a lot of talented contributors to this forum and we can all benefit from the experience and insight of others.

    However, I reject your apparent justification of rudeness on the basis of “…well that’s just their personality.”

    Telling someone that their project would benefit from being open source is valid and productive input. Telling someone that their project is of limited use because of bandwidth or other capability issues is also fair game. But these opinions can be communicated without being a tool about it..

  9. Great app and a great little tool to have when fiddling with IOT devices. I doubt that I could now lift the Tecktonix CROs we used in the 70s and I certainly couldnt justify the cost of a hi spec DSO. As someone who started in the stone age of computing (repairing down to transistor level in Control Data 3200 and 3300 computers) I appreciate how far semiconductors have come and just how much technology underpins the Scoppy project.

  10. I’ve actually found the Scoppy app and provided circuits really handy. I’ve produced some PCBs to be used with the app based on the front-end design #5. If anyone is interested in trying one out, wavr.info

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