[HN Gopher] Flea-Scope: $18 Source Available USB Oscilloscope, L...
___________________________________________________________________
Flea-Scope: $18 Source Available USB Oscilloscope, Logic Analyzer
and More [pdf]
Author : burgerone
Score : 196 points
Date : 2025-02-16 15:08 UTC (7 hours ago)
(HTM) web link (rtestardi.github.io)
(TXT) w3m dump (rtestardi.github.io)
| burgerone wrote:
| Edit: Licensing consists of ARR, Public Domain and MIT.
|
| https://github.com/rtestardi/StickOS2/blob/main/license.txt
|
| https://github.com/rtestardi/usbte/blob/master/LICENSE
| turtleyacht wrote:
| All Rights Reserved (ARR)
| analog31 wrote:
| Also, looks like some parts are patented.
|
| https://patents.google.com/patent/US8117587B1
| burgerone wrote:
| Correct. What should I replace "FOSS" with so that the
| title stays short and concise but correctly reflects the
| licensing/rights situation?
|
| I'm very new to posting on this platform.
| fragmede wrote:
| "partially source available" is maybe a bit long, but
| something along those lines?
| gpm wrote:
| My advice is to stay away from "FOSS" unless you're GPL,
| and "open source" unless you're an OSI-certified license.
| It's not that I don't think those terms apply to anything
| other than that, but using those terms invites debate
| about licensing and attempts to control language instead
| of discussion of your project.
|
| "Source available" is a term that usually no one gets mad
| at.
| analog31 wrote:
| Good question, and I sympathize.
|
| The thread title as of this moment (subject to moderator
| edit) says "source available" which seems reasonable. So
| I don't think you made a mistake. "With published design"
| might also work.
|
| I've got my own little GitHub page with projects that I
| share. They usually involve both hardware and code. I'm
| also not an engineer, but a scientist and electronics
| hobbyist, both of which have cultures of open design that
| predate the software industry. What I do with my projects
| is attach a MIT license, attribute the sources of any
| code or ideas that I borrow from elsewhere, and wish you
| good luck. ;-)
| rmu09 wrote:
| Strange patent. At first glance you could do something
| similar with an intel 8052AH BASIC (a 8051 type
| microcontroller with integrated basic interpreter) back in
| the 90ies.
| analog31 wrote:
| Indeed, I built simple industrial controllers from
| 8052AH-BASIC chips. And lots of patents are strange.
| Sometimes the examination process results in a narrowing
| of the claims to the point where they don't really read
| on anything.
| bramhaag wrote:
| edit: parent was heavily edited, so this comment makes less
| sense now.
|
| Note that calling this FOSS is completely inaccurate. Some
| parts are all rights reserved, some are public domain and some
| are only available for non-commercial use.
|
| Public domain is not open source, and especially not free (as
| in freedom). Restricting commercial use is also not free. At
| best, this project is partially source-available.
| patrick451 wrote:
| The only thing more frustrating than a rustacaen redefining
| "safety" to suit their purpose is a Stallman discipline
| redefining freedom to mean something totally weird. Something
| in the public domain is not free? Give me a break.
| tonetegeatinst wrote:
| Can I get some context for the rustacian safety thing? I'm
| honestly interested if that's real.
| gpm wrote:
| "Memory safety" is a concept that predates rust, but was
| certainly popularized by it. It refers to statically
| eliminating a category of bugs - those related to
| misusing memory - and all sources of undefined behavior.
|
| Rust code without unsafe blocks guarantees memory safety,
| and when you're writing unsafe blocks you're culturally
| expected to expose a safe-api that upholds rust's memory
| safety guarantees for users who don't themselves use
| unsafe blocks.
|
| Rust programmers (rustaceans, a pun on crustacean because
| the language mascot is a crustacean) tend to extol the
| virtues of memory safety [1], and are sometimes lax with
| using the word "safety" to refer to "memory safety".
| There are obviously non-memory-safety safety
| considerations as well (e.g. the other 1/3rds of security
| vulnerabilities. Or all the non-software uses of the word
| like making buildings that don't fall down).
|
| Personally I think it's usually pretty clear how the word
| is being used, and don't find it annoying. But then I'm a
| rust programmer.
|
| [1] E.g. pointing out that roughly 2/3rds of security
| vulnerabilities are caused by the lack of it.
| bramhaag wrote:
| > Something in the public domain is not free?
|
| Copyright law is tricky. Under US law, "public domain"
| means "not copyrighted", the author waives all rights and
| the law allows them to release their works to the public
| domain. This you can consider free.
|
| In other jurisdictions, say The Netherlands, the
| "Auteurswet" does not have a way for you to release your
| source code into the public domain, making any such
| statement void. Other countries such as Germany do not
| allow the author to waive all rights ("Urheberrecht"), etc
| etc.
|
| Without knowing where the software was written, by whom the
| software was written and with whom it is shared, you cannot
| guarantee anything from "public domain" software.
| fragmede wrote:
| > Public domain is not open source, and especially not free
| (as in freedom).
|
| The Free Software Foundation (FSF) and Open Source Initiative
| (OSI) recognize public domain software as "free software,"
| but not as open source, but as I understand it, it's not
| _that_ different from MIT licensed software. Someone can take
| MIT licensed code, make changes, sell the resulting binary as
| proprietary code and no one else is allowed to take that
| binary and sell it as theirs. There are some subtle other
| differences, but MIT licensing doesn 't require other
| people's changes get contributed back out as open, same as
| public domain.
| bramhaag wrote:
| The OSI does not recognize source code released to the
| public domain as free [1], because this "will depend where
| the software was written, where you are located, who the
| author is and where the people you are sharing the software
| with are located."
|
| [1] https://opensource.org/blog/public-domain-is-not-open-
| source
| dkjaudyeqooe wrote:
| > Public domain is not open source, and especially not free
| (as in freedom)
|
| How so? There are no restrictions on use or distribution.
|
| > Restricting commercial use is also not free.
|
| I agree, and I would include neutering any commercial uses,
| in which case GPL is non-free.
| bramhaag wrote:
| > How so? There are no restrictions on use or distribution.
|
| It's not open source because it does not use an open source
| license (public domain is not a license). It's not free
| because this depends on your and the author's jurisdiction
| (if you both live in the US, then yes there are no
| restrictions on use or distribution)
|
| > I would include neutering any commercial uses, in which
| case GPL is non-free.
|
| In what way does GPL neuter commercial uses? GPLv3 simply
| states that you have to make your code available to your
| users (note: users, not everyone), not that you cannot sell
| your product.
| dkjaudyeqooe wrote:
| Jurisdictions always matter, other OS licenses are also
| subject to local laws and its not a given they will be
| valid or interpreted as intended. Arguably it's the
| intention of the creator of the software that matters in
| how licenses are actually enforced (or not). So in that
| sense PD is fine. There are also plenty of easy cures for
| PD, such as making changes and then copyrighting and
| licensing that derived work as required.
|
| The GPL forces you to license all your relevant software
| under restrictive terms (ie under the terms of the GPL).
| How people can declare that as 'free' I'll never
| understand, it's just ideological nonsense.
|
| The GPL makes it hard or impossible to make money from
| your software since anyone else can duplicate and sell
| it. That's obviously neutering commercial use.
| dvh wrote:
| For comparison, this is what $2 USB scope (800ksps, 2 voltage
| ranges) look like: https://files.catbox.moe/0t0dq3.jpg
| burgerone wrote:
| For yet another comparison, scoppy is a similar project:
| https://github.com/fhdm-dev/scoppy
| bobmcnamara wrote:
| I made something like this in college with a spare ADC,
| resistor divider, and an 8052.
| assimpleaspossi wrote:
| *sigh*
|
| Link doesn't work.
| dvh wrote:
| I'll put it on GitHub tomorrow
| serviceberry wrote:
| I think projects like that would have been a godsend 2-3 decades
| ago, when even a basic oscilloscope costed as much as a used car.
|
| Nowadays, _very_ good oscilloscopes with 200 MHz bandwidth, good
| user interfaces, and responsive displays are selling for $300 - I
| 'm talking Siglent, Rigol, UNI-T. So the merits of DIYing
| something much worse just aren't quite there. It's that one piece
| of equipment you use to troubleshoot all your other designs, so
| you want it to be dependable, easy to use, and accurate.
|
| This is not to say it's not a fun, geeky project to work on and
| publish... but you know, _only once you have a real
| oscilloscope_. If you 're just setting up, do yourself a favor
| and spend a bit more money on this. The remaining equipment is
| not nearly as critical.
| iceflinger wrote:
| I think there's something to be said for the form factor here
| though: I can see myself owning one of these just to take as
| part of a kit if I expect to need to do some troubleshooting
| away from my typical workspace.
| nicolaslem wrote:
| I have a cheap handheld oscilloscope (ZOYI ZT703S, ~$80) that
| I find very convenient to have around. It's the size of a
| multimeter, runs on a battery and works well enough that I
| don't feel too limited by it.
| yjftsjthsd-h wrote:
| I think there's a difference in options at $200/$20/$2 (see
| elsewhere in this thread) just in lowering the bar to entry to
| the point of triviality. I'm not spending $300 without knowing
| exactly what I want it for, $20 is easy, $2 is an impulse buy.
| serviceberry wrote:
| Fair enough, but on the flip side - you either want to get
| into electronics or not. If not, there's no real point in
| spending the money, even if it's $2. If you do, then you
| probably don't yet have an understanding of what features you
| need, and the cheapest option will actually hold you back.
|
| Some specific issues: first, the number of inputs. A lot of
| circuit debugging is about "let's see how signal A looks like
| when signal B happens" (B might be a bus clock or something
| like that). So, a lot of the time, you need two inputs, not
| one.
|
| Second issue: even hobby MCUs generally run faster than 4
| MHz, so you might need more bandwidth to monitor I/O, even
| for old-school Arduino stuff - let alone RP2040.
|
| Third issue: for anything analog, from audio equipment to
| household appliances, the 0-6 V input range just doesn't cut
| it.
|
| I'm not trying to dunk on this project: I think it's about as
| good as you can do for the price, and it's clearly a passion
| thing for the author. But _if you can afford it_ , and if you
| want to learn electronics, a "real" oscilloscope is almost
| certainly a better deal.
| burgerone wrote:
| Rich designed it with trigger IO pins to be able to easily
| chain them. While the UI doesn't support managing multiple
| Flea-Scopes at once, you can just open the UI multiple
| times, which does seem like a reasonable option to me.
|
| As as others have pointed out before, there's just no
| alternatives in this form factor. The scope is tiny, and
| for what it is it packs quite a punch. 3.3V and 5V are
| standard logic levels which will suffice for quite a lot of
| basic probing. Being made for students, it does likely
| everything that would be required of it in an educational
| environment. How well this pans out in real-life we'll see
| soon.
|
| Granted that with enough money and space at hand there are
| much better options out there.
| sangnoir wrote:
| > you either want to get into electronics or not. If not,
| there's no real point in spending the money, even if it's
| $2
|
| It's fuzzier than that; there are hobbies that look fun but
| I can't decide if I want to fully invest into them, but
| having a cheap, but not-great equipment is a good stepping
| stone. Besides, beginners won't have the skill to fully use
| fully-featured pro-level-gear. A cheap soldering iron is
| great for those looking to get their feet wet; sure the
| lack of precise temperature control can be a hinderance,
| but investing in an expensive soldering station is wasteful
| if one decides that it's not really for them.
| 05 wrote:
| Ironically, beginners would benefit the most from a good
| soldering station, proper liquid flux and leaded solder.
| Seasoned electronics guys can probably solder anything
| with a cigarette lighter and a scrap piece of metal, but
| using proper tools makes a huge difference when you're
| just starting and might mean not dropping the hobby
| altogether because of a lousy first experience..
| burgerone wrote:
| In his presentation video [0] Rich explicitly states that his
| goal is to make electronics approachable for the younger
| generation. A low barrier of entry in almost all directions is
| a key component in that in my opinion.
|
| [0]: https://www.youtube.com/watch?v=sbRXDkHS_V0
| chefandy wrote:
| It's a matter of perspective, though. For a white collar
| professional in the US? Sure. For most of the world's
| population, the distinction between $300 and $18 is extremely
| consequential.
| sangnoir wrote:
| For the majority of humanity, it's several days' worth of
| wages vs several weeks or months.
| chefandy wrote:
| Right. $18 is 6% of $300. For that to be a difference of
| little consequence, $300 must be an expenditure of little
| consequence. In the other direction $300 is 6% of $5000.
| There are people-- a number of whom likely frequent this
| forum-- for whom a $5000 expenditure isn't particularly
| consequential, and getting an OK thing for $300 doesn't
| make sense when you can get a pretty good thing for $5000.
| That certainly doesn't mean someone being able to offer a
| useful version of a $5000 thing for $300 has no merit.
|
| I see this sort of thing in amateur radio all the time.
| "Why on earth would anyone just starting out consider
| getting a Baofeng radio for $20 when you can get a better
| quality name brand equivalent for $200?" Well because $180
| is a whole lot of money for a whole lot of people.
| andyjohnson0 wrote:
| Nowadays I have a fairly decent Rigol scope, which suffices for
| my modest and infrequent needs. But back when I was a teenager
| I had very little money but plenty of time. A cheap DIY option
| would have made a lot of difference to me. I hope project this
| makes a difference to people on a budget, of whatever age.
| WheatMillington wrote:
| There is still a WIDE gap between $18 and $300.
| ericol wrote:
| > very good oscilloscopes with 200 MHz bandwidth, good user
| interfaces, and responsive displays are selling for $300
|
| This is a very strong first world POV. Those U$D 300 rank
| pretty high across world's minimum salaries [1], not to mention
| that prices can very likely double in countries like my own.
|
| Moreover, a large % of people that can really get a very good
| use of this (Kids in high school) usually have a lot less money
| at their disposal, and we are not getting into collaterals like
| building your own and learning how it works.
|
| [1]
| https://en.wikipedia.org/wiki/List_of_countries_by_minimum_w...
| BubbleRings wrote:
| I totally agree.
|
| Want to keep a distractable 14 year old busy for an hour?
| Give him or her some wire, a cheap meter, a battery, some
| switches and LEDs. Want to possibly change that kid's life?
| Give him the above, plus a scope, and hook it up to a music
| player playing his favorite song.
| dghlsakjg wrote:
| I get what you're saying, but there are also fully
| functioning oscilloscopes for far less.
|
| For the purposes you are talking about you can get what you
| need with one of the $20-40 scopes.
|
| Those ones also tend to be portable and more rugged which is
| what you need if you don't have a full blown lab to keep a
| nice oscilloscope in.
| ericol wrote:
| Note: the intention of this comment is just to be
| informative.
|
| I did a quick search in my country's Mercado Libre (the
| local Amazon, we could say) and the cheapest available one,
| Fnirsi-138 Pro [1] goes for a price of aprox. 50 USD [2]
|
| [1] https://www.amazon.com/Digital-Oscilloscope-Portable-
| Samplin...
|
| https://www.mercadolibre.com.ar/osciloscopio-digital-
| fnirsi-...
| burgerone wrote:
| what makes the Flea-Scope so particularly interesting to me
| is that you get I think 9 channels worth of digital inputs
| all at once. That is hard to beat for the price.
|
| Regarding raw specs, it seems to be much better in most
| regards compared to the mentioned Fnirsi-138 Pro.
| jboy55 wrote:
| So starting with nothing at all, what is the total cost of
| ownership for the flea -cope? My guess, its over $300, (if
| $300 is your annual salary, your existing phone will probably
| not cut it). And for comparison, standalone toy oscilloscopes
| (<10Mhz bandwidth) go for $30 and under (some $11), with
| screen, on AliExpress. And a "decent" one, like OWON, is
| around $150.
|
| The problem is, with a toy scope, you aren't really gonna
| know if what you're measuring is real. This might be useful
| as a kit to build to learn how to program microcontrollers,
| or measure audio signals (the $11 one, or the mic on your
| phone can do this), but a bad scope will generally cause more
| problems for the hobbyist. When you get near the limit of a
| scope's bandwidth, the signals get really messy and full of
| artifacts. Arduinos run at 8-16Mhz, so you're gonna hit a
| wall really quickly and once you can't rely on the output,
| the investment will be lost.
| burgerone wrote:
| Where's that guess coming from? The scope is $18, the
| optional probe from elecrow is $5 extra. You most
| definitely have either an android phone or a laptop/PC with
| a browser from the last ten years already. As such the cost
| is pretty minimal. Say you bought a set of these kind of
| test probes with hooks at the front. A set would maybe cost
| you $10. Now you can use all your 9 channels. I don't
| understand your price calculations.
|
| Every scope out there has an upper limit in terms of speed.
| If you have no use for it, don't buy it. This oscilloscope
| is first and foremost a learning resource.
| gary_0 wrote:
| The future has been here for a while but remains unevenly
| distributed.
| OJFord wrote:
| That's a very fair point, but it's also fair to discuss
| things with a 'first world' point of view. The same way it
| can be humourous or eye-opening to point out something's a
| 'first world problem', but if that's where you live then that
| is a problem, that is something you're looking to address.
|
| We're all looking to do the best we can from different
| baselines.
| cushychicken wrote:
| The new Rigol DHO800 series are _fabulous_ bargains for the
| money, and extremely well designed in a lot of ways:
|
| - 12 bit ADC frontends
|
| - Actually usable touchscreen inputs
|
| - Super simple to drive remotely over a network connection
| (though getting the IP address with just the touchscreen is a
| little tricky)
|
| - USB-C power input - you can run it from a battery pack if you
| like!
|
| - All the essential decoders built in for free (I2C, SPI, UART)
|
| - VESA Mountable - I got a monitor arm to gain back some desk
| space ( _awesome_ feature)
|
| - Very, very easy to hack one of the budget models and upgrade
| it to a 250MHz model :D
| djray wrote:
| These start from 450 euros.
| cushychicken wrote:
| Well worth the money if you work with electronics with any
| kind of regularity.
|
| Maybe a bit pricy for the hobbyist.
| analog31 wrote:
| I got one recently, and it's been a pleasure to use. My only
| regret is not getting the 4 channel version, though I've only
| needed 2 channels so far. But at my workplace, I've found
| that an extra channel is the thing that helps me solve a
| problem, more frequently than higher performance does.
|
| I'm an old timer so I'm familiar with the traditional scope
| front panel, but have come to like the touch screen for
| changing settings.
|
| Perhaps my only gripe is how long it takes to boot.
| logtempo wrote:
| You can put, for the same price, almost 20 fleascope in a
| classroom instead of one profeasional one.
|
| I think it does have its place even today.
| selfhoster wrote:
| This is crazy. The ones we used in the Navy were heavy and
| delicate. Now it fits into the palm of our hand. Just incredible
| how far things have come.
| Aurornis wrote:
| We've had cheap, tiny USB oscilloscope and logic analyzers for
| well over a decade. They're all over Amazon and Aliexpress.
|
| The cool thing about this one is that it's open source and well
| documented.
|
| There are a lot of downsides: The front end has poor input
| protection and the entire unit is much less resilient,
| calibrated, and trustworthy than what you'd use in the Navy.
| mikewarot wrote:
| Have you tried using a NanoVNA? Those things are amazing. For
| << $100, you get a device that can measure SWR, attenuation,
| impedance, generate Smith charts, from about 10 Khz to 4 Ghz+
| to a reasonable extent.
|
| Oh, and RTLsdr dongles are fantastic deals too, when coupled
| with the GNU Radio project.
| fryd_w wrote:
| The flea-scope's hybrid FPGA/MCU architecture for USB streaming
| is clever - using FPGA pipelining to handle 100MS/s capture
| paired with an STM32 for protocol translation is sweet cost-wise.
| BUT, the 8-bit ADC resolution and lack of input protection
| networks (compared to Rigol's 1MO//20pF frontends with
| overvoltage clamping) make it risky in case of unattenuated
| signals.
|
| The Python analysis toolkit using NumPy/SciPy for FFTs instead of
| baked-in DSP shows cool resource partitioning - could see Jupyter
| soon.
| jesperwe wrote:
| The specs say 12 bit though.
| picture wrote:
| I'm wondering if we looked at the same document... there is no
| FPGA and it is PIC32MK0512GPK064 instead of STM32. It's also 12
| bits at nowhere near 100 Msps, being only 18 Msps.
|
| Did you use the aid from AI to write the comment, or are you
| referring to another device?
| atoav wrote:
| Mandatory caveat: beware of ground loops when using a USB
| oscilloscope! Most budget USB scopes share ground with your PC
| via the USB port. If you're probing high-voltage circuits (e.g.,
| mains power, switching supplies), this can create a dangerous
| potential difference, risking damage to your computer or worse.
| Some scopes offer isolated inputs, but if yours doesn't, use
| differential probes or an isolation transformer. Otherwise, you
| might end up debugging your laptop's fried USB controller instead
| of your circuit.
| burgerone wrote:
| On page 9 of the linked document Rich also addresses this and
| calls for the use of a full-speed usb isolator
| analog31 wrote:
| On a related note, I once fried the built in audio hardware of
| my laptop. I even saw smoke coming out one of the vents. The
| rest of the computer survived.
| nayuki wrote:
| Does the software provide a way to export recorded waveforms to
| allow analysis in other programs? And what is the maximum number
| of samples it can record?
| burgerone wrote:
| Recording, exporting and interpreting waveforms doesn't seem to
| be amongs the objectives of the scope interface.
|
| Over on hackaday [0] Rich explains that you can however easily
| grab the data directly from the serial port using python and
| thus record it:
|
| > (07/28/2024) Sorry, there is no protocol analysis -- just
| digital display. You can invoke a "scope" command by python or
| something, and get the data yourself in binary -- I have an
| example of that in StickOS2 repo python/scope.py, but it is
| very rough. (Analog has additional challenges of having to do
| calibration, but digital is easy.)
|
| [0]: https://hackaday.io/project/192598-flea-scope-usb-
| oscillosco...
| alexray wrote:
| What's the use case you're trying to solve for here?
| nayuki wrote:
| Using an oscilloscope to find a signal, then writing custom
| DSP code to decode the signal. I'm thinking of stuff like 1
| or n-wire binary protocols, NTSC, and such. Or am I supposed
| to be looking at software-defined radio (SDR) hardware?
| brcmthrowaway wrote:
| Anything I can buy for $50?
| dzhiurgis wrote:
| I've always been fascinated by oscilloscopes, but I don't dabble
| in electronics. Is there any use of it for normal homeowner?
| mikewarot wrote:
| For about the same price ($13), I'm happy with this logic
| analyzer I bought through amazon[1] a month ago. I spent more on
| probes[2] ($24) than I did the analyzer. ;-)
|
| To power it, I'm using SigRock/Pulseview[3], which sees it as a
| compatible clone. It's wild to be able to see signals a few tens
| of nanoseconds wide so cheaply.
|
| [1] https://www.amazon.com/dp/B077LSG5P2
|
| [2] https://www.amazon.com/dp/B0CLB63GL3
|
| [3] https://sigrok.org/wiki/PulseView
| djmips wrote:
| Yeah, those are awesome. I found that a great use was to
| profile microcontroller code. Setting various GPIO pins high /
| low around critical sections of code. Then you can see the
| results in SigRock.
| jamesy0ung wrote:
| I have this exact one, and I don't reccomend using it with the
| Saleae Logic software, it constantly drops out and has issues
| enumerating. Haven't tried sigrock yet.
| jszymborski wrote:
| Reminds me of the similarly priced EspoTek Labrador
|
| https://espotek.com/labrador/
| nerdralph wrote:
| Not as capable as Flea-Scope, but buck50 is another MCU-based
| oscilloscope and logic analyzer.
| https://github.com/thanks4opensource/buck50
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