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| Decoding oscope? |
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| nctnico:
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. |
| luma:
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. |
| HenrikWo:
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... |
| HenrikWo:
--- Quote from: nctnico on October 27, 2023, 09:55:21 am ---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. --- End quote --- Newer (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. |
| pdenisowski:
--- Quote from: nctnico on October 27, 2023, 09:55:21 am ---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. --- End quote --- As 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 this :) And 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 :) |
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