Rigol Ds1074z I2C Decode event table only shows one packet. - Page 1
Forum section: electronics / testgear

author: nealz
author_rank: Unknown
timestamp: May 20, 2014, 01:11:11 am
content: After working on this all evening I assume I'm missing something simple.I am decoding/triggering I2c successfully however I can only read the first 9 bytes (The data I'm sending is approximately 18 bytes).If I reduce the horizontal I get more data but loose the decode.How do I zoom in on the decode that I capture?Additional the event table only shows the last packet (First 9 bytes and then a .).Each successive packet overwrite the first (id 1) line of the Event Table.Is this the way the event table works or am I doing something wrong?Maybe I'm expecting to much of the Decode feature of a scope.If approprate I'd appreciate suggestions on less then $200 I2C/SPI/RS232 decoders.Appreciate your feedback.FYI I'm running version 00.02.01.SP1 if it matters.

author: Rigby
author_rank: Super Contributor
timestamp: May 20, 2014, 01:17:20 pm
content: It decodes based on what's on screen. If you click the horizontal timebase knob you can get a zoomed in view that may work for you.

author: marmad
author_rank: Super Contributor
timestamp: May 23, 2014, 05:05:37 pm
content: Quote from: nealz on May 20, 2014, 01:11:11 amIt would be a lot easier to help you if you posted settings/images along with your questions. I have a DS2000 (not DS1000Z) although I suspect the decoding is very similar. The number of packets you can capture is determined by the timebase and sample length settings.Attached are 2 images made using 7Mpt sample length capturing 6 R/Ws (14 bytes - although it could be longer) - first is at 200us/div with event table displayed, second one is zoomed to 50us/div.

author: 8086
author_rank: Super Contributor
timestamp: May 23, 2014, 05:16:55 pm
content: As Rigby said, the DS1074Z decodes whatever is on screen. I generally do a long capture, then press the horizontal scale knob and zoom in/scroll across to decode more.

author: nealz
author_rank: Unknown
timestamp: May 26, 2014, 06:10:31 pm
content: Thanks Rigby, Marmad and 8086 for the reply.Sorry for the Delay work get's in the way of Fun.I attached to screen grabs of a I2C decode. The packet is 18 Bytes but I only see the first 9 Bytes.If I change my horizontal I can see the Waveform but if I adjust the position to the right the decode stops.I can see the rest of the waveform but not decode once the Start Bit goes off the screen (just Green Line).

author: 8086
author_rank: Super Contributor
timestamp: May 26, 2014, 06:21:07 pm
content: Have you tried scrolling a little more so that you have the start of the next byte on screen and no parts of the previous byte? Does it work then?

author: marmad
author_rank: Super Contributor
timestamp: May 26, 2014, 06:36:49 pm
content: Quote from: nealz on May 26, 2014, 06:10:31 pmI'm still not clear on exactly what you're trying to do. Are you trying to get the decode to work on all 18 bytes while the DSO is running? Or are you capturing the data, and then stopping the DSO to examine it? Because if it's the first - it probably won't work: while running, the DSO decodes only what's after (or directly before) the trigger point and decipherable in display memory - and display memory is not detailed enough for 18 decoded bytes simultaneously. If it's the second thing you're trying to do (capture the data, stop the DSO, examine them) - then it shouldn't be a problem if you adjust your timebase and sample length correctly.Look at the difference between my images and yours: I have STOPped the DSO after capturing 7Megs of sample data, and am zooming in - and the event table works correctly.

author: Fagear
author_rank: Regular Contributor
timestamp: June 18, 2014, 11:03:17 pm
content: As I discoveredin my review of the DS1104Z-S, decoders are sometimes useless. No contest in compare with DS2000A series. RS232 is 50/50, SPI is doing well, but I2C is pretty useless.Problem is: DS1000Z decodes ONLY from screen memory! If edges are washed out (too slow sweep) or there is no "start" combination on the screen (no matter what is in sample memory): decoder will fail. RSR232 will show corrupted data and I2C will simply turn off. Only SPI can show something.Once again: DS2000A decodes from sample memory, DS1000Z decodes from display memory.You can see ithere in my video(Russian voiceover).

author: Rigby
author_rank: Super Contributor
timestamp: June 19, 2014, 12:27:35 am
content: So zoom in... Or just get a BusPirate or something like that. They are very capable little things, and very inexpensive. My employer purchased a Logic-16, and that thing is pretty epic. The software is lacking in some ways, but its very capable, and *extremely* useful.

author: Fagear
author_rank: Regular Contributor
timestamp: June 19, 2014, 10:01:25 am
content: Quote from: Rigby on June 19, 2014, 12:27:35 amI need to say: when DS1000Z in "zoomed" mode ("delayed sweep") it ignores everything on the upper half (where full waveform is) and decoder works only on the bottom half. And once again: if there is no "start" I2C condition on bottom half - decoder will stop. No matter what is on the upper half of the screen and in the sample memory. Totally different to what DS2000 does.Comparehere (DS1000Z)andhere (DS2000A).

author: andyturk
author_rank: Frequent Contributor
timestamp: August 03, 2014, 01:23:27 am
content: Sorry for the thread spelunking, but I just ran into an issue with I2C decode on my DS4014...I've got I2C trigger and decode working directly after the scope triggers on some data. However, in "delayed sweep" mode, when I zoom in to show more detail, the waveforms update as expected, but the decode doesn't. I.e., it shows the decode data using the initial capture timebase, not the timebase for the waveform display. Same for scrolling back and forth horizontally. I've reset the scope and the behavior is still there. It's really annoying!The only work-around I've found is to tweak one of the decode trigger levels after updating the timebase. This forces it to recalculate the decode info. Is there some way to get the scope to recalculate the decode automatically?

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 03, 2014, 12:42:44 pm
content: Is the DS1000Z really only decoding from screen memory and not from sample memory?How come the implementation between DS1000Z and DS2000A is that different?Both have a big sample memory.Maybe this can be configured somewhere in a menu? Or maybe the new software would fix this?I was really going to decide on buying a DS1000Z (or maybe even a MSO1000Z) as it seemed to handle everything for my needs, just a lower B/W, sample rate and sample memory.Maybe the MSO1000Z is better in this respect?How to check this? Can it be verified from the user manual, before I buy any of the scope?

author: Electro Fan
author_rank: Super Contributor
timestamp: August 03, 2014, 06:17:00 pm
content: A couple related things:1. On my DS2072 using RS232 I can decode (ASCII, Binary, Hex, and Decimal) in real-time. If I change the time base to the point where the decode values are too small to render in the green decoder boxed and then change from Run to Stop I can expand back out and see the decoded values for a fairly long capture no problem. Maybe this is something the 2000 series does that the 1000 and 4000 series don't do, or maybe it's just something that works on the RS232 - but perhaps not on I2C.2. Speaking of I2C (and SPI), I haven't figured out how to probe and examine and generally learn to use I2C (and SPI). Anyone have any easy entry level methods of learning to examine, decode, and generally get a handle on I2C and SPI? I have seen a few boards that might provide a testbed for learning. Here is one I came across (I can post others if anyone is interested):http://www.totalphase.com/support/articles/200473206-I2C-SPI-Activity-Board-User-Manual

author: janoc
author_rank: Super Contributor
timestamp: August 03, 2014, 06:19:38 pm
content: Quote from: pascal_sweden on August 03, 2014, 12:42:44 pmApparently it should be possible to switch the decoding source. On my DS1074Z, there is an option (you need to scroll down the right decode menu and it is under Settings, I believe) where you can select the source - by default it decodes from the screen and according to the manual, it should be possible to change it to decode from the entire capture memory. However, for me the option is always greyed out and I haven't found a way to enable it yet.Jan

author: janoc
author_rank: Super Contributor
timestamp: August 03, 2014, 06:25:24 pm
content: http://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdfPage 175, it is the "DataSrc" option. For me it is always set to "Trace" and greyed out, so I cannot change it.

author: asgard20032
author_rank: Regular Contributor
timestamp: August 04, 2014, 02:12:37 pm
content: I am about to buy a DS1074z, if someone can clarify the DataSrc thing...

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 04, 2014, 03:21:00 pm
content: Maybe someone who already owns a DS1074Z or MSO1074Z can post this on the Rigol support forum? This way we can get feedback if they consider this as a bug, and if there will be a fix coming soon.Myself am going to order very soon an MSO1074Z, or an MSO2072A. Still doubting about which one is the best, but most likely it will be the MSO1074Z, as 100 MHz (after possible upgrade) would be enough for my current applications.But I really want confirmation that feature wise both scopes are as good. It should only be better in B/W and in Sample rate, but not in feature set, if I am correct.

author: asgard20032
author_rank: Regular Contributor
timestamp: August 04, 2014, 03:37:50 pm
content: Same for me, deciding between DS1074 or DS2000A serie... need to be set on my choice by the end of the day. For doing digital stuff, with from time to time maybe some analog.If I understand well,DS2000A:2 channelmore g/samplemore b/w8 inch screenless bug (like this data source thing)can decode CAN (not a big deal, for simple thing, like I2C and RS232, scope are great, but with more complicated protocol, better to use a true logical analyser and use scope to check signal integrity)more button and knob (knob for each channel)better GUI (subjective, not sure about that statement)harder to hackDS1000Z:more channel (4)the problem with data source for decoder7 inch screenless button/knobGUI not as good as DS2000Aeasier to hackAlso, any info on the connectivity of the scope with a function generator from rigol? which scope can connect to which waveform generator model?

author: David Hess
author_rank: Super Contributor
timestamp: August 04, 2014, 03:53:46 pm
content: These oscilloscopes support triggering on the decoded data, right? In order for that to happen without a lot of dead time, the decoding has to happen during decimation which could be related to why one can only decode the display record although that does not explain its other limitations.Maybe marketing and product segmentation triumphed over engineering again.

author: Mark_O
author_rank: Frequent Contributor
timestamp: August 05, 2014, 02:12:32 am
content: Quote from: pascal_sweden on August 04, 2014, 03:21:00 pmThey're not. So you won't get the confirmation you desire.QuoteYou're not correct, and I'm unsure why you think it "should" be so? There has been a huge amount of discussion here in this Forum over the last year, and the fact that there are significant feature differences between the two is well established.That's actually one of the factors that makes picking one over the other more difficult. It it were simply that one is higher performance, at a higher price, with two channels... and the other lower performance (but still good), except with 4 channels AND cheaper, it would be much easier. But go back and read comments from folks like ElectroFan and others, who started out with a 1000, switched to a 2000, and were happy they did. See their reasons why. And I'm sure some moved in the other direction, because 4 channels were more important to them (as it would be for me).I don't recall all the Feature differences that I've written about in numerous posts here, much less all those that others have written about. But off the top of my head, the 1000-series claims to support HD Video, but defines HD as 480P. The 2000 actually does 720 and 1080 (i.e., real HD). The 2000 claims to decode SPI, but with only 2 channels, really can't. The 1000 does. They both do segmented captures, however there are time stamps on the segments with the 2000, but none on the 1000. The 2000 can post-process segments to compare them, and identify those that deviate by X%, and quickly jump between them. The 1000 can not. They each have their own set of bugs, and annoyances. But seemingly less so than the 4000-series.There are a number of other differences, but that should be enough to demonstrate that a simplified comparison will miss many factors.

author: andrewwong2000
author_rank: Contributor
timestamp: August 05, 2014, 02:59:29 am
content: Suggest you keep your 1074z as an oscilloscope and use a Saleae or something like it.Doing any real serial data stream analysis is a pain with a small screen and a bunch of buttons, but the scope is quick and essential for checking signal quality and basic framing.That's what I am doing with my 1074..

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2014, 08:44:41 am
content: Quote from: David Hess on August 04, 2014, 03:53:46 pmYes, the DS1074Z can trigger on I2C or SPI data. It is a bit fiddly, but you can trigger on things like start condition, stop condition, missed ACK, address or data packet content ...In order to trigger on something you don't need to decode the entire memory - just keep looping trying to decode the samples as they are coming in. So I don't see why there should be a big delay.

author: janoc
author_rank: Super Contributor
timestamp: August 05, 2014, 08:58:37 am
content: Quote from: andrewwong2000 on August 05, 2014, 02:59:29 amI don't like the little USB logic analyzers too much. I have the Open Bench Logic Sniffer, it works fine, but the workflow is a PITA. You have to record the data until the memory is filled and only then you can have them decoded/analyzed. There is no real time decoding, which is often useful. Also you have to restart the capture from scratch manually if you want to continue decoding. I haven't used the Saleae one, but from the reviews I believe it is a similar type of analyzer.On the Rigol I can set the decoding up, set the trigger to normal mode and have every packet decoded as soon as it arrives. Much faster if all I need is to check whether e.g. keyboard data are arriving over I2C correctly - with the logic analyzer I would have to arm the capture, pray that it doesn't trigger on some spurious edge or spike (as there is no sophisticated triggering on it) and then hit a key on the keyboard to generate the signal I want to capture. And then spend some time setting up the decode to actually see the dataGranted, most of these are probably usability issues of the SUMP client software, but the lack of the real time capture/decoding and primitive triggering (only bit transitions and some basic bit patterns) is a hardware limitation. On the Rigol I could just keep hitting the keyboard keys - the decoding is much faster and the capture is re-armed automatically when I am in normal trigger.Not to mention that the scope is all the time on my bench, ready to be used. The logic analyzer has to be wired up, the software set up, all in all it is worth taking out only if I need more than the 4 channels that I have on the Rigol, which is rarely the case. Also being able to see the shape of the signals coming in is handy - you don't have that with the logic analyzer (well, the new Saleae ones can do it, but then you don't have proper probes ...)

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 05, 2014, 09:32:03 am
content: In the thread above there is an indication that there are many differences between DS1074Z and DS2072A in terms of features.But these differences are caused by the software.Strictly speaking, the DS1074Z should be able to do everything that the DS2072A can do, just less B/W and sample rate.In the current SW implementation there is much differences, but for me it is hard to believe that Rigol would not be able to make all DS2072A features available in the DS1074Z.The HW in the DS1074Z is good enough to support all of the DS2072A features!In fact it even has 4 analog channels. If they would just make the software feature complete, this would be the best scope out there if you don't need more than 100 MHZ B/W.

author: tautech
author_rank: Super Contributor
timestamp: August 05, 2014, 09:45:56 am
content: Quote from: pascal_sweden on August 05, 2014, 09:32:03 amYou are making some sweeping statements/assumptions here.Be ready for all the replies to the contrary.

author: Mark_O
author_rank: Frequent Contributor
timestamp: August 05, 2014, 12:44:18 pm
content: Quote from: tautech on August 05, 2014, 09:45:56 amYes, no kidding. Along with a whole lot of wishful thinking.QuoteWell, I'm not sure it's worth the trouble. Apparently, he has no concept of product differentiation, and that a manufacturer may have valid reasons NOT to make the feature sets identical. Regardless of how hard that is for him to believe. Or the fact that while they are similar, they don't have exactly the same hardware, and thus may be more limited in capabilities.What he should be saying is "I don't understand", because he doesn't. Or that he finds it disappointing. That's certainly a valid sentiment, that many of us could get behind. Instead he's making proclamations of how he thinks things should be, because that would be his preference. He started out by claiming theywerethe same, then when corrected, shifts tothey should be.I'd certainly like it if Rigol added CAN decode to the 1000Z-series, but they've specifically told me they won't. And lack of time-stamps on segmented captures on the 1000Z is something I've been told theycan'tadd. Probably some internal architectural detail they're not about to share.Saying "it's just software", and "it should be able to", and "it is hard to believe" just demonstrates a lack of understanding of how things work in the real world. And is a denial of the reality of the limitations of products that exist.When we evaluate and discuss the variety of scopes that are out there, we explore what their capabilities actually are. That's a learning process, but it let's us weigh the pro's and con's, and select which unit is most appropriate for our specific needs. The needs aren't the same for everyone, so neither will the devices selected be. Making suggestions to manufacturers about features or capabilities we'd like to see supported is appropriate. As is criticism of limitations we feel unnecessarily reduce their value to us. However, insisting that "strictly speaking", things should be such and so, helps no one, including the person trying to decide which unit is right for them. Who, as a result, winds up never making any choice at all.

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 05, 2014, 01:37:23 pm
content: You have a valid point about product differentiation, and that they deliberately are not releasing the features.Regarding limitations on the hardware side, I have a hard time to understand honestly.The scope has A/D converter on the input. The moment the signal is sampled and available in digital memory, you can basically do everything with it what you want, if you have a decent processor architecture.CAN is just a matter of releasing support for it.Time stamps should be the same, as they have a reference clock.

author: marmad
author_rank: Super Contributor
timestamp: August 05, 2014, 01:47:20 pm
content: Quote from: pascal_sweden on August 05, 2014, 01:37:23 pmMan, look at photos and read descriptions about the insides of the 2 DSOs. They use different A/D converters (the DS1000Z is quad-interleaved), different processors, and, IIRC, the DS1000Z uses one FPGA for post-processing, while the DS2000 uses two. They're NOT the same hardware - and won't run the same software features at the same speed - which is another reason Rigol doesn't try to offer identical features.Plus, you're discounting one of the HUGE main hardware features of the DS2000 - the spring-loaded Navigation knob. Without that, being able to record and investigate ~60k segments - as well as just moving through Delayed Sweep waveforms - would be a major pain in the ass (not to mention just setting certain variables without it).

author: pascal_sweden
author_rank: Super Contributor
timestamp: August 05, 2014, 02:35:26 pm
content: Yes, the architecture is different of course.It would be too slow to offer all software features with one FPGA probably, and that's why it comes with a reduced feature set.The discussions here have been about the need of 4 channels. But if most of the work is digital, then the solution might be to go for MSO2072A? Then you have 2 analog channels, and 16 digital channels. The SPI decoding would be done by the logic analyzer, and no need to sacrifice any of the analog channels.Maybe I should just go for an MSO2072A. That is, if they make the current SW stable in that version.

author: e_60
author_rank: Contributor
timestamp: January 07, 2015, 03:35:48 pm
content: I know this is an older thread, but I could not find any more current thread on the topic. I have a MSO1104Z which I was looking to use for some quick decoding and confirmation, vs pulling out and connecting a dedicated logic analyzer. I ran into this same issue discussed above where, the DataSrc is only on trace and greyed out, so this makes decoding almost useless as I can never see more than a few bytes at a time, have to keep scrolling horizontally as bytes shift through the event log. Zooming out to get more bytes visible on the screen results in the decoder starting to just show 0's. I noticed as long as the horizontail timebase is under 100ms the decoder is on, if you try to view more than 100ms it will automatically turn off, but in practice I cannot even decode 1ms of data on the screen.

author: Howardlong
author_rank: Super Contributor
timestamp: January 07, 2015, 04:02:56 pm
content: Yep, you have to zoom in and decode, it will only do a screen's worth. The event table is therefore pretty much useless.If you have an idea what you're looking for the serial trigger can be useful, but I wouldn't bet my life on it consistently triggering. That's not a statement that it doesn't work, it does, I'm just not convinced it works all the time.

author: Rigby
author_rank: Super Contributor
timestamp: January 08, 2015, 03:25:29 am
content: Scopes are scopes. Logic analyzers are logic analyzers. If you dont need realtime visualizing and you just want to capture and decode, get a Saleae and live happy.

author: Mark_O
author_rank: Frequent Contributor
timestamp: January 08, 2015, 07:01:28 am
content: Quote from: Rigby on January 08, 2015, 03:25:29 amWell, that's one (extremely simplistic) opinion.What about those who don't "just"? Those who need or want BOTH realtime visualizing, AND the ability to capture and decode longer sequences? They need a device that does things right. Which apparently is NOT the MSO1000z series, which has dumbed-down some functionality to the point of being worthless. That doesn't mean that all MSO's are so limited.[And BTW, I have used a Saleae, and there were many ways I didn't just "live happy" with it. In fact, it was quite poor. So it's no panacea, as you have implied.]

author: Rigby
author_rank: Super Contributor
timestamp: January 08, 2015, 01:31:16 pm
content: well the Saleae is perfect for what I do. I don't need realtime but I do need to be able to write my own protocol decoders and I need to capture arbitrary lengths of data. So, yeah the Saleae is useful for me.I wasn't trying to imply that it is a perfect solution for everyone, because nothing is a perfect solution for everyone, and everyone knows that.Regarding the MSO1000Z - you get what you pay for, I guess. How many pieces of test gear can you cram into one inexpensive body before you wonder if it all really works like you imagine it will?The decoding limitations of the M/DS1KZ are known. They were known before the MSO1KZ line came along.

author: e_60
author_rank: Contributor
timestamp: January 10, 2015, 03:02:07 am
content: I understood going into the purchase there were limitations to the built-in logic analyzer of this lower end oscilloscope, however I did not anticipate that the functionality would be so heavily crippled. I made an assumption that I would be able to decode the captured memory, the manual specifically described the function of decoding from trace as default, not as the only choice… there is an event table and payload screen which further suggests you will be looking at more than a few bytes. I don’t think my assumption/expectations were unreasonable.I picked up an MSO2072A yesterday which so far does exactly what I expected from it as a logic analyzer, and the ribbon cable is much nicer than the MSO1000Z one.

author: pickle9000
author_rank: Super Contributor
timestamp: January 10, 2015, 04:34:32 am
content: Quote from: Rigby on January 08, 2015, 01:31:16 pmWhen you are getting a design up and running or if there is a repair a scope with protocol decoding is an excellent tool. Once up, a device like a Saleae is ideal for getting your software up to snuff. There are scopes that can do both but there is always cost to consider.I personally consider a Saleae a protocol decoder and not a logic analyzer. It is however a very good protocol decoder and useful tool for a programmer.

author: Mark_O
author_rank: Frequent Contributor
timestamp: January 10, 2015, 10:45:28 am
content: Quote from: e_60 on January 10, 2015, 03:02:07 amI'd agree with everything you said, 100%. (emphasis added)I believe those are expectations that anyone evaluating the unit would share, based on tech materials that are available.

author: Rigby
author_rank: Super Contributor
timestamp: January 11, 2015, 12:52:58 am
content: The shortcomings mentioned have been mentioned as being present on the DS1000Z series in the software decoding of signals captured on the analog channels, and this limitation is precisely why I purchased my first Saleae device. I mentioned it in the huge Rigol I2C decoding thread that contains all the rigol hacking info. No one made a stink about it then, and yeah, I don't know why. It is a pretty huge limitation.

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2015, 01:22:20 am
content: Sounds like Saleae are having issues, prices going up.

author: Rigby
author_rank: Super Contributor
timestamp: January 11, 2015, 11:04:53 pm
content: Quote from: pickle9000 on January 11, 2015, 01:22:20 amYeah. Shame because they have really good stuff. If this helps them get back in black I'm on board.

author: smgvbest
author_rank: Unknown
timestamp: January 14, 2015, 04:12:01 am
content: I posted this over in the DS1000Z wishlist thread and thought I would duplicate it here. I hope you do not mindQuote