Products > Test Equipment
SDS 1202 X-E I2C triggering bug
17_29bis:
Hello,
I just got a new SDS 1202X-E oscilloscope (OS) and I think I found a bug in the I2C triggering system. I wonder what other users of this particular OS think about this problem.
My OS runs v.5.1.3.13 firmware and has 0c-01 hardware version. I want to trigger on "7 bit Address& Data". I properly set up the triggering on "Start" condition and can observe, decode and examine the data exchange between i2c master (AVR, hardware i2c) and slave (LCD display, addr 0x3F). The data exchange is 99% constant, always start from writing 0x8C into the slave device:
I change the triggering mode from "Start" to "7 bit Address& Data" and set the I2C address to 0x3F and any data (0xXX)- trigger works fine:
Now I set the I2C address to 0x3F and the fist byte to 0x8C -trigger does not work:
But at the same time if I set the first byte to 0 the trigger starts working:
and this is wrong.
PS: this is my first post so please forgive me for not inserting the images right in the message body since it would be much easier to read the post - I simply could not figure out how to do that because the image tag could not display the images (in png format) stored on the remote ftp.
Regarding the spikes on the SDA line - you can safely ignore them.
Thanks!
tautech:
--- Quote from: 17_29bis on January 21, 2018, 07:10:30 am ---Hello,
I just got a new SDS 1202X-E oscilloscope (OS) and I think I found a bug in the I2C triggering system. I wonder what other users of this particular OS think about this problem.
My OS runs v.5.1.3.13 firmware and has 0c-01 hardware version. I want to trigger on "7 bit Address& Data". I properly set up the triggering on "Start" condition and can observe, decode and examine the data exchange between i2c master (AVR, hardware i2c) and slave (LCD display, addr 0x3F). The data exchange is 99% constant, always start from writing 0x8C into the slave device:
SDS00003.png
I change the triggering mode from "Start" to "7 bit Address& Data" and set the I2C address to 0x3F and any data (0xXX)- trigger works fine:
SDS00005.png
Now I set the I2C address to 0x3F and the fist byte to 0x8C -trigger does not work:
SDS00008.png
But at the same time if I set the first byte to 0 the trigger starts working:
SDS00009.png
and this is wrong.
Regarding the spikes on the SDA line - you can safely ignore them.
Thanks!
--- End quote ---
Welcome to the forum.
Can you be sure about the spikes ? Did you set the thresholds above them ?
--- Quote ---PS: this is my first post so please forgive me for not inserting the images right in the message body since it would be much easier to read the post - I simply could not figure out how to do that because the image tag could not display the images (in png format) stored on the remote ftp.
--- End quote ---
I embedded one to show you how.
Copy the image URL after posting, then Use Modify post and paste it within your text. Highlight it and use the Insert Image icon on the posting page.
Study the syntax used by Quoting this post.
17_29bis:
--- Quote from: tautech on January 21, 2018, 07:25:56 am ---Can you be sure about the spikes ? Did you set the thresholds above them ?
--- End quote ---
Yes, I am sure. I set the threshold for SDA line above and below the spike and it did not make any difference in triggering and decoding. Why? Because those spikes occur when SCL is low and therefore they don't matter in this case. I zoomed at the spike you can see that for yourself:
--- Quote from: tautech on January 21, 2018, 07:25:56 am ---Copy the image URL after posting, then Use Modify post and paste it within your text. Highlight it and use the Insert Image icon on the posting page.
--- End quote ---
Interesting approach, no wonder I could not figure that out. Thanks for the hint.
BTW, is there any place where I can check for firmware updates for this o-scope? I heard about Facebook but I don't have an account and don't want to create one. I checked Siglent website and could not find any firmware updates for this device at all.
17_29bis:
I decided to use a standalone logic analyzer (threshold level - 1.8V), this is addition info about the spikes:
tautech:
--- Quote from: 17_29bis on January 21, 2018, 08:01:50 am ---BTW, is there any place where I can check for firmware updates for this o-scope? I heard about Facebook but I don't have an account and don't want to create one. I checked Siglent website and could not find any firmware updates for this device at all.
--- End quote ---
There's been one since release but you've got the latest which came out last July. The last units I got just before Xmas had the same version.
The US site is in a bit of a mess ATM and doesn't display the full list like the Chinese and Hamburg sites do.
http://siglenteu.com/gjjrj.aspx?id=15&page=1
I've shown a a few posts of I2C decoding but only while using the Siglent STB3 test board.
The Decode functionality has been mentioned as 'not quite right' in this thread for the 4ch X-E.
https://www.eevblog.com/forum/testgear/siglent-sds1104x-e-in-depth-review/
Since the 2ch version is very similar it might be afflicted with a similar problem that I don't see using the Siglent test board.
For both the 2 and 4ch X-E's, we expect some of these reported issues to be sorted in new firmware shortly.
I still have a nagging suspicion that the spikes are some of the cause of the problem but others smarter than I might have a better idea. :-//
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