Decoding oscope? - Page 1
Forum section: electronics / testgear

author: Tech_Monkey
author_rank: Contributor
timestamp: October 26, 2023, 08:24:13 pm
content: I dont really know what Im talking about here so hope you guys can help. My other half is in school for EE and was working on a project with a MSP 430 board. simple program that outputs the hex of a letter / word in I2c (?) anyone know of a cheap oscope that can decode the signal and display it?

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2023, 08:40:17 pm
content: Get a cheap logic analyzer. It is far better for decoding protocols and WAY cheaper than the cheapest scope with decoders. Like thishttps://www.amazon.com/HiLetgo-Analyzer-Ferrite-Channel-Arduino/dp/B077LSG5P2or one of million other variations. They all are basically the same.Also, I2C requires two devices on the bus to work, you can't just output stuff like you do with UART, for example.

author: Tech_Monkey
author_rank: Contributor
timestamp: October 26, 2023, 08:45:12 pm
content: there is some sort of daughter board involved so Im sure she already knew that and had it covered. just looking to upgrade her home lab a little for her.

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2023, 08:51:06 pm
content: Cheap scopes don't have good decoders that are not frustrating to use. If you want to get a scope, then get it for the scope itself.And it is always better to ask what SO needs. Event the cheapest decent scope (and not a toy) will cost $300-500. It is a lot of money to spend blindly without evaluating actual needs.

author: tautech
author_rank: Super Contributor
timestamp: October 26, 2023, 08:58:24 pm
content: Quote from: Tech_Monkey on October 26, 2023, 08:24:13 pmDefine cheap.

author: Fungus
author_rank: Super Contributor
timestamp: October 26, 2023, 09:15:45 pm
content: Quote from: Tech_Monkey on October 26, 2023, 08:24:13 pmI know of a few but is it worth paying $400 or more just to do this?(I wouldn't advise spending less on an oscilloscope, if you're investing in one you might as well get one that's actually worth owning and they start around $400)The definition of "cheap" is relative though... and an oscilloscope is an essential tool for anybody who's serious about EE.

author: mwb1100
author_rank: Frequent Contributor
timestamp: October 26, 2023, 09:48:38 pm
content: Quote from: Tech_Monkey on October 26, 2023, 08:24:13 pmIt might be worth looking into something like a Digilent Analog Discovery or the similar Analog Devices ADALM2000. Can act as a logic analyzer that decodes I2C and other serial protocols, and can perform as several other devices (oscilloscope, waveform generator, power supply etc).Not necessarily cheap when bought new ($300-400), but can be found for $100 or so on eBay - especially at the end of the school term when students are unloading the ones they no longer need. Also, I understand that there are student discounts (maybe good ones through a school purchasing program?). But as others have said, the student needs to be involved in the decision to make sure it's something that would actually be useful for their projects.

author: ADT123
author_rank: Regular Contributor
timestamp: October 27, 2023, 04:41:53 am
content: As others have said if you only need to decode and display the hex data then a cheap logic analyzer should do the job.An oscilloscope captures and displays waveforms then one of the many things modern ones can do is decode and display the hex data (I say modern ones as its possible your other half's school has older ones that can not). If your other half wants to continue with electronics then a scope is far more versatile and powerful than a logic analyzer but does cost more. I am biased (see my signature below) but PicoScope oscilloscopes can decode over 30 different protocols including I2C and start at under $200. Here is a page about I2C decoding using a scopehttps://www.picotech.com/library/oscilloscopes/serial-protocol-decoding-i2c

author: pdenisowski
author_rank: Super Contributor
timestamp: October 27, 2023, 09:36:55 am
content: Quote from: ataradov on October 26, 2023, 08:40:17 pmFor someone doing a school project, a cheap (~10 USD) logic analyzer is the way to go.I've done lots of compare and contrast of logic analyzers (cheap and not-so-cheap) and oscilloscopes. There are plenty of cases where a scope with an MSO option is preferred or even necessary, but my guess is that a cheap USB based analyzer would probably be sufficient in this case.If you're curious how serial decodes are done on a scope, here's a video I made about how we do it on our MXO series oscilloscopes (for information / education: not suggesting you buy an MXO for a school project)

author: pdenisowski
author_rank: Super Contributor
timestamp: October 27, 2023, 09:50:51 am
content: Quote from: mwb1100 on October 26, 2023, 09:48:38 pmEE students at North Carolina State University (my alma mater) were required to purchase the Analog Discovery for some of their basic circuits labs. It does a lot of different things and has a very small form factor (USB/PC based).I've used one extensively and my feeing is that it's barely adequate for undergrad academic use: I've never seen one in a "proper" lab outside of academia. The price, even with the academic discount, has also gone way up recently. My feeling is that it made perfect sense to have students buy them during COVID so they could do their own labs at home, but I think students are always better served using traditional standalone, discrete instruments.One thing I really do like about the AD2 is the serial / digital pattern generator - if you need to emulate or create an arbitrary serial or even parallel (!!!) data pattern, the AD2 is an easy way to do this compared to other methods (although the new Batronix demo board addresses this now)https://www.eevblog.com/forum/testgear/new-scope-demoboard-from-batronix/msg4898882/#msg4898882

author: nctnico
author_rank: Super Contributor
timestamp: October 27, 2023, 09:55:21 am
content: I'd get an oscilloscope. A logic analyser won't do you any good if you don't know the signals are OK. So using a logic analyser is the worst advice by far.Several years ago I was in a project where someone was stuck for 3 weeks trying to get an RS485 bus to work. So I was sent in to investigate. Turned out the person was using a logic analyser. Hooking the signals up to an oscilloscope revealed the actual problem in 5 minutes: the timing for switching between send & receive was all wrong and messing with the signal levels. But that is something you won't discover using a logic analyser.A decent oscilloscope which can decode starts at the US$500 mark. GW Instek and Micsig make oscilloscopes that decode full memory and not just what is on screen. This is important because it allows to zoom in on a signal without losing the decoding information.

author: luma
author_rank: Regular Contributor
timestamp: October 27, 2023, 12:34:35 pm
content: I'm going to throw in yet another recommendation for the Analog Discovery. It's perfect for this use case, easy to use, and the software is incredible. IT doesn't top out the spec charts and might not be the best tool on a dedicated repair bench, but for a student poking at digital circuits who wants a way to visualize what's happening, it's flippin perfect. Small size, reasonable price, huge amount of features.

author: HenrikWo
author_rank: Newbie
timestamp: October 27, 2023, 01:25:15 pm
content: If you're a student, you can also check out Salea's devices. (https://www.saleae.com)If you are only looking for a logic analyzer, then the Logic 8 is certainly sufficient. With the Logic Pro 8 you even get a halfway decent PC oscilloscope. Software works flawlessly and platform dependent.Two years ago they sold the Logic 8 for 199 USD and the Logic Pro 8 for 429 USD to students. Just ask...

author: HenrikWo
author_rank: Newbie
timestamp: October 27, 2023, 01:33:28 pm
content: Quote from: nctnico on October 27, 2023, 09:55:21 amNewer (and not the very cheap) logic analyzers do the same. Yes, they are usually much more BW limited than an oscilloscope, but they have more channels and tend to be a bit cheaper!@Tech_Monkey: Bandwidth and sample rates are very important information that you should pay attention to.

author: pdenisowski
author_rank: Super Contributor
timestamp: October 27, 2023, 02:24:22 pm
content: Quote from: nctnico on October 27, 2023, 09:55:21 amAs someone who works for a company that makes oscilloscopes (but not logic analyzers), I also wholeheartedly agree that a scope is the best choice for thisAnd I've seen the scenario you describe (not decoding because of a bad physical layer) many, many times.My recommendation was simply based on budget: not sure if the OP wants to drop $500 or more to buy a scope for what might be a one-off university project.The best solution might be to see if there is a lab on campus that has an appropriately equipped scope: in my experience, the "good stuff" is often sitting in the grad lab and/or professor's personal lab, not in the Circuits I lab

author: Tech_Monkey
author_rank: Contributor
timestamp: October 27, 2023, 04:12:15 pm
content: Quote from: pdenisowski on October 27, 2023, 09:50:51 amSo funny enough. I am orginally from NC, and my SO wants to attend NC state for her masters. I have always been a wolfpack fan and i think I have turned her into one as well. Do you think her trying to get in there for her masters is worth it and/or doable? Shes super smart, hard working and has a pretty good GPA, as well as planned physics and math minors. Shes doing research this summer with someone in the RF labs to help pad the resume, and after she graduates were taking a trip to alaska where she wants to teach at the community college there for a couple semesters just to help out (if anyone needs the help that is)anyways, back on topic Thanks everyone for your advice. I Really just wanted to do something nice to upgrade her lab equipment as shes already building quite the collection. I going to follow the advice of looking for some decent used equipment on Ebay. Thanks again.

author: TomKatt
author_rank: Frequent Contributor
timestamp: October 27, 2023, 04:49:44 pm
content: As others have pointed out, oscopes with decoding features are typically limited in their decoding ease of use and overall feature set, especially in 'more affordable' gear. A cheap generic decoder running open source Sigrok software usually outperforms this tier of scopes.Certainly, an oscope is a useful tool and if the logic analyzer fails or spits out garbage, it's handy to inspect the waveform for issues. At that point, the Digilent Analog Discovery starts looking good.IMO, a $10-$20 investment for a generic LA is a good starting point - you can always move up to better equipment later if you need to. But for that price, why not just get one to see if it does the job ?

author: pdenisowski
author_rank: Super Contributor
timestamp: October 27, 2023, 05:15:44 pm
content: Quote from: Tech_Monkey on October 27, 2023, 04:12:15 pmI got my MSEE from NC State and several members of my family also got their engineering degrees there, and we were all very happy with the program.I don't think a lot of people realize how big the College of Engineering is at NC State: it's one of the 10 largest engineering programs in the United States (~10,000 engineering students). The graduate program is also very robust: at the Spring 2023 commencement there were almost twice as many ECE Master / PhD degrees awarded (black gowns) compared to undergrads (red gowns).So yes, definitely do-able and worth doing in my opinion.

author: Tech_Monkey
author_rank: Contributor
timestamp: October 31, 2023, 01:44:47 pm
content: Quote from: pdenisowski on October 27, 2023, 05:15:44 pmWith numbers like that maybe she should pick a different degree