Low Cost PCB's Low Cost Components

Author Topic: Rigol Ds1074z I2C Decode event table only shows one packet.  (Read 11274 times)

0 Members and 1 Guest are viewing this topic.

Offline nealz

  • Contributor
  • Posts: 15
  • Country: 00
  • Hack... Hack till it works.
After working on this all evening I assume I'm missing something simple.  :-DD

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.
 

Offline Rigby

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
  • Learning, very new at this. Righteous Asshole, too
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #1 on: May 20, 2014, 11:17:20 PM »
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.
 

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2986
  • Country: aq
    • DaysAlive
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #2 on: May 24, 2014, 03:05:37 AM »
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?

It 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.
 

Online 8086

  • Super Contributor
  • ***
  • Posts: 1081
  • Country: gb
    • Circuitology - Electronics Assembly
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #3 on: May 24, 2014, 03:16:55 AM »
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.
 

Offline nealz

  • Contributor
  • Posts: 15
  • Country: 00
  • Hack... Hack till it works.
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #4 on: May 27, 2014, 04:10:31 AM »
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).
 

Online 8086

  • Super Contributor
  • ***
  • Posts: 1081
  • Country: gb
    • Circuitology - Electronics Assembly
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #5 on: May 27, 2014, 04:21:07 AM »
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?
 

Offline marmad

  • Super Contributor
  • ***
  • Posts: 2986
  • Country: aq
    • DaysAlive
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #6 on: May 27, 2014, 04:36:49 AM »
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).

I'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.
« Last Edit: May 27, 2014, 04:42:36 AM by marmad »
 

Offline Fagear

  • Regular Contributor
  • *
  • Posts: 83
  • Country: ru
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #7 on: June 19, 2014, 09:03:17 AM »
As I discovered in 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 it here in my video (Russian voiceover).
 

Offline Rigby

  • Super Contributor
  • ***
  • Posts: 1475
  • Country: us
  • Learning, very new at this. Righteous Asshole, too
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #8 on: June 19, 2014, 10:27:35 AM »
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.
 

Offline Fagear

  • Regular Contributor
  • *
  • Posts: 83
  • Country: ru
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #9 on: June 19, 2014, 08:01:25 PM »
So zoom in...
I 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.
Compare here (DS1000Z) and here (DS2000A).
 

Online andyturk

  • Frequent Contributor
  • **
  • Posts: 699
  • Country: us
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #10 on: August 03, 2014, 11:23:27 AM »
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?

 

Offline pascal_sweden

  • Super Contributor
  • ***
  • Posts: 1373
  • Country: no
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #11 on: August 03, 2014, 10:42:44 PM »
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?
 

Offline Electro Fan

  • Super Contributor
  • ***
  • Posts: 1651
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #12 on: August 04, 2014, 04:17:00 AM »
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
 

Offline janoc

  • Super Contributor
  • ***
  • Posts: 1819
  • Country: fr
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #13 on: August 04, 2014, 04:19:38 AM »
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?


Apparently 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

 

Offline janoc

  • Super Contributor
  • ***
  • Posts: 1819
  • Country: fr
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #14 on: August 04, 2014, 04:25:24 AM »
http://www.batronix.com/pdf/Rigol/UserGuide/DS1000Z_UserGuide_EN.pdf

Page 175, it is the "DataSrc" option. For me it is always set to "Trace" and greyed out, so I cannot change it.
 

Offline asgard20032

  • Regular Contributor
  • *
  • Posts: 171
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #15 on: August 05, 2014, 12:12:37 AM »
I am about to buy a DS1074z, if someone can clarify the DataSrc thing...
 

Offline pascal_sweden

  • Super Contributor
  • ***
  • Posts: 1373
  • Country: no
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #16 on: August 05, 2014, 01:21:00 AM »
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.
 

Offline asgard20032

  • Regular Contributor
  • *
  • Posts: 171
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #17 on: August 05, 2014, 01:37:50 AM »
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 channel
more g/sample
more b/w
8 inch screen
less 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 hack

DS1000Z:
more channel (4)
the problem with data source for decoder
7 inch screen
less button/knob
GUI not as good as DS2000A
easier to hack


Also, any info on the connectivity of the scope with a function generator from rigol? which scope can connect to which waveform generator model?
 

Offline David Hess

  • Super Contributor
  • ***
  • Posts: 5171
  • Country: us
  • DavidH
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #18 on: August 05, 2014, 01:53:46 AM »
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.
 

Offline Mark_O

  • Frequent Contributor
  • **
  • Posts: 939
  • Country: us
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #19 on: August 05, 2014, 12:12:32 PM »
But I really want confirmation that feature wise both scopes are as good.

They're not.  So you won't get the confirmation you desire.

Quote
It should only be better in B/W and in Sample rate, but not in feature set, if I am correct.

You'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.
 

Offline andrewwong2000

  • Contributor
  • Posts: 32
  • Country: au
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #20 on: August 05, 2014, 12:59:29 PM »
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..
 

Offline janoc

  • Super Contributor
  • ***
  • Posts: 1819
  • Country: fr
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #21 on: August 05, 2014, 06:44:41 PM »
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.

Yes, 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.

 

Offline janoc

  • Super Contributor
  • ***
  • Posts: 1819
  • Country: fr
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #22 on: August 05, 2014, 06:58:37 PM »
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..

I 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 data :( Granted, 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 ...)

« Last Edit: August 05, 2014, 07:23:07 PM by janoc »
 

Offline pascal_sweden

  • Super Contributor
  • ***
  • Posts: 1373
  • Country: no
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #23 on: August 05, 2014, 07:32:03 PM »
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.
« Last Edit: August 05, 2014, 07:33:38 PM by pascal_sweden »
 

Offline tautech

  • Super Contributor
  • ***
  • Posts: 9628
  • Country: nz
    • Taupaki Technologies Ltd.
Re: Rigol Ds1074z I2C Decode event table only shows one packet.
« Reply #24 on: August 05, 2014, 07:45:56 PM »
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.
You are making some sweeping statements/assumptions here.  :o
Be ready for all the replies to the contrary.  :box:
Avid Rabid Hobbyist & NZ Siglent Distributor
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf