Products > Test Equipment
Siglent SDS2000X Plus - Bugs / Missing Features / Feature Requests
Slartibartfast:
--- Quote from: Performa01 on December 04, 2023, 01:10:50 pm ---
--- Quote from: Slartibartfast on December 04, 2023, 12:28:30 pm ---Why do you talk about thresholds (plural)? I can only set one threshold, presumably valid for both clock and data.
--- End quote ---
Huh?
--- End quote ---
Sorry for that, I messed that up, talking from memory, rather than checking.
In my measurements, both were set to 2V.
Cheers Peter
rf-loop:
And if we want make better.
Oscilloscope decoder need have more settings for signals.
Now there is only one threshold for one signal.
In I2C is is better if there are separate thresholds for High state and Low state.
Typical definition is that signal level is High if level is >70% and it is Low if level is <30%
Or different depending circuits used.
Other possibility is set threshold and hysteresis.
The decoder should use as precisely as possible the specified limit values according to the specification or the values used by the examined bus. Otherwise, the decoding may show an error even though the actual traffic is working or vice versa.
Anyway, it kind of bothers me that only one HI/LO threshold (with unknown hysteresis) is set for each signal (in this case for SCL and SDA) when in reality there is an accepted level window for 1 and an accepted level window for 0 and the level window between these are "undefined" status. Although these are not really hardcore analyzers. Still, it would be good to strive for better.
Slartibartfast:
--- Quote from: Performa01 on December 04, 2023, 01:03:19 pm ---The preferred way to deal with that is to set up the decoding until it works fine
--- End quote ---
>:D Rookie's method (trial and error) to set up the decoding? >:D
I prefer to use an informed choice for the thresholds.
PS.: I think rf-loop has an important point.
--- Quote ---What does the manual say? The latest manual (EN01D) gives the same example as older versions to set the image format, default path and basis filename for screenshots together with some options for the visual appearance in chapter 29.3.2 on page 317. This is still valid even for the unreleased V1.6.0 beta firmware. This example isn’t a particularly good one, because BMP is certainly not the screenshot format of choice; what we really want is PNG!
--- End quote ---
Shame on me, I was still on EN01C. But as you say, EN01D is no different (well, they chose to replace a font in EN01C that was really nice to read, particularly on screen, by one in EN01D that's rather awful on anything but printed on paper).
On the issue of the default path: Pages 312 to 314 each show a menu that has the option "Save Path" or "Recall Path" with "Internal" and "External". These options do not exist on my scope. When saving/recalling via mouse or on-screen-finger one can choose this via the file manager. This does not work, though, when hitting the PRINT button. So, concrete question: How do I set the scope up such that after powering up, without messing with menus first (i.e. by default), hitting PRINT saves the screenshot in a particular folder, that is not called 'SIGLENT', on the thumb drive?
The page you're mentioning explains all a sort of things by using menus. It does not explain how to set up defaults. In fact, the only sentence in the manual where the word 'default' refers to a path, is "The default save path is \SIGLENT\." (Page 318 EN01D)
--- Quote ---I’ve never tried it (I do not use a mouse), but it’s said that the mouse pointer is not visible in the screenshot if you move it to the border of the screen.
--- End quote ---
I do not use a mouse either, as it takes too much space on a lab table. A trackball is just perfect for this purpose. What I cannot stand at all is fatty fingerprints on screens.
In any case, your suggestion is off the point. During normal workflow I would create screenshots during the development work, and when writing documentation, I choose from those. During development I do not have documentation on my mind, and certainly would not care where the pointer is. I wonder if this would be much different for anybody.
--- Quote ---Since I’ve currently not set up a network connection, I do all picture transfers via USB stick at the moment. This includes 4 DSOs, where the SDS2000X Plus and HD see the most use by far and the USB stick is plugged and unplugged dozens of times a day. Never ever did I have any issues like that.
--- End quote ---
Same for me, I also used to save directly to my NAS, but I'm without network at the moment. So it's possible the issue was there before, I just didn't notice because I did not use thumb drives at the time. Well, I'll keep watching out, might be a hardware issue.
Cheers Peter
Slartibartfast:
--- Quote from: rf-loop on December 04, 2023, 01:58:44 pm ---And if we want make better.
Oscilloscope decoder need have more settings for signals.
Now there is only one threshold for one signal.
--- End quote ---
Sorry, that was my mistake. There are indeed two settings, separate for CK and D. But I share your opinion
--- Quote ---In I2C is is better if there are separate thresholds for High state and Low state.
Typical definition is that signal level is High if level is >70% and it is Low if level is <30%
Or different depending circuits used.
Other possibility is set threshold and hysteresis.
--- End quote ---
and would even prefer high / low thresholds over having separate thresholds for the two lines.
--- Quote ---The decoder should use as precisely as possible the specified limit values according to the specification or the values used by the examined bus. Otherwise, the decoding may show an error even though the actual traffic is working or vice versa.
--- End quote ---
Correct. However, AFAIK I²C does not specify the thresholds. The values for the involved chips could be used, however the chips on the bus do not all have the same thresholds, and sometimes the master, sometimes a slave drives the D line, or listens to the level. A perfect decoder that takes all that into account is immensely complex, as it needs to figure out which device is driving the line at any particular moment.
Cheers Peter
rf-loop:
--- Quote from: Slartibartfast on December 04, 2023, 02:46:52 pm ---
--- Quote from: rf-loop on December 04, 2023, 01:58:44 pm ---And if we want make better.
Oscilloscope decoder need have more settings for signals.
Now there is only one threshold for one signal.
--- End quote ---
Sorry, that was my mistake. There are indeed two settings, separate for CK and D. But I share your opinion
--- End quote ---
No, there IS only one threshold for one signal in SDS2000X Plus, SDS2000X HD and many other Siglent oscilloscopes (and many others too). Example SCL (this is one signal in my context) have just one threshold. Can not define threshold for High state level and Low state level.
Here's an example of how NXP says general information related to their stuff and views on I2C definitions.
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