Siglent SDS 1104X-E sanity check - Page 1
Forum section: electronics / testgear

author: jgoney
author_rank: Newbie
timestamp: September 30, 2019, 09:51:17 pm
content: Hi!Sorry my first post on here is so dumb. In the course of trying to debug a microcontroller project (literally just toggling an STM32 pin high and low), I noticed that my pulse waves are not as sharp as I expected; they're quite slewed looking when you zoom in on them. To try to investigate further, I hooked the probe up to the calibration terminal and noticed the same thing (see attached pic). Since I'm still pretty new to electronics I'm hoping you guys can tell me whether this is normal, whether I have something wrong in my setup, or whether I might have a problem with the scope and/or probe.Any thoughts/ideas?

author: tautech
author_rank: Super Contributor
timestamp: October 01, 2019, 12:07:50 am
content: Welcome to the forum.2 things, ~750ns rise time is not slow by any means however the old firmware your scope is running on doesn't tell us if you're using the probe on 1x or 10x where 1x would load the pulse more and so return a slower rise time.Update the firmware to the latest version 6.1.33.You can get it here and after unpacking the package check the release notes for any intermediate versions you might have to install before the latest.https://www.siglenteu.com/service-and-support/firmware-software/digital-oscilloscopes/#sds1000x-e-series

author: Fungus
author_rank: Super Contributor
timestamp: October 01, 2019, 12:29:11 am
content: Quote from: tautech on October 01, 2019, 12:07:50 amYes it is.Quote from: jgoney on September 30, 2019, 09:51:17 pmSTM32 chips have selectable rise times on the I/O pins. Make sure you're choosing a fast one.

author: rstofer
author_rank: Super Contributor
timestamp: October 01, 2019, 01:24:27 am
content: Also check that the pin isn't set up for Open Collector output with, perhaps, an internal resistor pull-up. That kind of output lacks a pull-up MOSFET so rise time will be slow.

author: maginnovision
author_rank: Super Contributor
timestamp: October 01, 2019, 02:35:53 am
content: Considering the SS is of a 1kHz square wave... That's probably just the probe cal signal, right?

author: jgoney
author_rank: Newbie
timestamp: October 01, 2019, 08:45:50 am
content: Quote from: tautech on October 01, 2019, 12:07:50 amThank you! I'll update the firmware a bit later and report back if there's any difference. I'm pretty sure that the probe and input were both set to 10x, but I'll double-check just to be sure.Quote from: maginnovision on October 01, 2019, 02:35:53 amYes, exactly. Sorry for not being clearer about that, but the screencap is just of probing the cal signal. This is my first "real" oscilloscope, so I wasn't sure if seeing such slow rise times are normal or not.

author: rf-loop
author_rank: Super Contributor
timestamp: October 01, 2019, 10:22:39 am
content: Quote from: jgoney on September 30, 2019, 09:51:17 pmMay I ask how you have get SDS1104X-E with older than FW 6.1.25R2 what was first version where attenuation was displayed in channel info. So your FW version must be 6.1.25R1 or older.Is it possible you tell what is your version, least I'm interested where from can get so old version and how old it is. Unbelievable.Please update it to latest what is today 6.1.33And follow instructions (pdf) what are inside update ZIP exactly.And seriously: USB need be native FAT32 format!Test USB stick with scope before use it for FW update.Remember after FW and immediately after scope have beencontinuouslyon over 30 min you need do Selfcal before use (and nothing connected to any inputs of course). Because this update change cal related things lot of.After then you have LOT of improved scope. Totally many things changed.For me your signal looks like 1kHz calibration square is connected to CH1 using Probe 1x.(Probe 1x/10x switch. Scope 1x 10x or what ever do not affect freq response at all but probe using 1x is around 5 -7 MHz and 10x something more.I think your probes what come with scope are PP510 what are "100MHz" (in real world well over) and this is only when probe is set for 10x (and then also scope for 10x so that level numbers are ok))If any problem you can also PM (finnish if it help)ETA:Sorry I forget SDS1104X-Eprobe cal outputrisetime is very slow, reason was not probe possible 1x. (Yes it is ok forprobe LF responseadjustment purpose for what it is made)Difference between 1x and 10x is quite small because output risetime is slow.Here images what are normal with PP215 probe and SDS1104X-E Probe cal output.With probe set 1X and 10X. (with PP510 probe situation is quite same in this case.)Of course risetime may have small differences between scopes because it is not at all critical for purpose it is made (probe LF cal)Probe 10X Probe Cal outputProbe 1X Probe Cal output

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 01, 2019, 10:35:45 am
content: Note that pretty much any sharp edge will become very sloped when zoomed in sufficiently.

author: tv84
author_rank: Super Contributor
timestamp: October 01, 2019, 11:06:49 am
content: Quote from: Mr. Scram on October 01, 2019, 10:35:45 amYou made me remember that any "parallel lines intersect at a point which lies on the line at infinity."

author: Fungus
author_rank: Super Contributor
timestamp: October 01, 2019, 02:54:05 pm
content: Quote from: jgoney on October 01, 2019, 08:45:50 amQuote from: jgoney on October 01, 2019, 08:45:50 amSlow rise times are normal on cal signals, yes.

author: borjam
author_rank: Unknown
timestamp: October 01, 2019, 02:58:21 pm
content: Quote from: tv84 on October 01, 2019, 11:06:49 amActually:- A fat point is the intersection point of two astute lines.- Astute lines are those parallel straight lines that intersect on a fat point.

author: jgoney
author_rank: Newbie
timestamp: October 01, 2019, 04:07:33 pm
content: Thanks for everyone's help, I appreciate it. It seems like the scope is working/configured correctly....it's just that the cal terminal is a bit slow.I updated the firmware as advised, so thanks for that! It was running 7.6.1.12R1. fwiw, I ordered this from BatterFly last October.I'll try the advised tips on the STM32 stuff to see if I can get a sharper edge on my wave.Thanks!

author: rf-loop
author_rank: Super Contributor
timestamp: October 01, 2019, 08:43:01 pm
content: 7.6.1.12R1 was from December 2017 and you buy it October 2018 when current version have been quite long time 6.1.25R2. Just unbelievable but as can see - all is possible.But, what ever it have been previously now you have lot of improved scope, nearly like new "different" model.There is lot of differences now. FFT is now lot of better. New BodePlot II (if you use it at all) is totally huge jump up from old version, like totally new reference - new benchmark for any other manufacturers in this or even bit higher price group.Then lot of small improvements like vertical and horizontal ref position mode selection, channel trace display can turn off (example if use one channel like ext trigger etc), lot of improved serial trig and decode function, also free user defined probe multiplier and better working history buffer and better working fast sequence, lot of improved XY mode with up to around 60kwfm/s backround wfm/s speed with full time domain (XT) measurements and many other things and then of course also bug fixes.And still some improvements coming later.QuoteScope out from factory box with original probe (10X setting) can reach roughly around 3ns risetime if signal under test source impedance is quite low. (and if you look bit around here and there and so on... you may soon find 100MHz limit has not been carved in stone... )