Author Topic: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)  (Read 117041 times)

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Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #150 on: January 06, 2017, 08:34:46 pm »
Apparently USB opto-isolators are a thing.  I didn't know that, but this is just an example from Google of a fairly reputable sounding one.

http://uk.farnell.com/olimex/usb-iso/usb-isolator-1000vdc-for-pc-laptop/dp/1795095?mckv=fvKfxZhD_dc|pcrid|78108470709|&gross_price=true&CATCI=pla-131293226229&CAAGID=20220744309&CMP=KNC-GUK-GEN-SHOPPING-OLIMEX&CAGPSPN=pla&gclid=CKiy19mhrdECFW4A0wodOisBqQ&DM_PersistentCookieCreated=true&CAWELAID=120173390000303585

Actually, isolators but not opto-isolators. They use on-chip (or at least in package) inductive coupling. They're pretty much all based on the Analog Devices ADUM4160...

http://www.analog.com/en/products/interface-isolation/isolation/standard-digital-isolators/adum4160.html

Note that these USB isolator products state USB2.0 compliance but when you look closer, their maximum supported speed is USB Full Speed (12Mbps) not USB2 High speed (480Mbps). This works with the VDS1022(I) because of its high level of front end processing and also things like USB audio DACs, but won't work with the Hantek, simple USB logic analysers etc. because their USB streaming needs USB High Speed to get enough throughput.

You also need to get enough power across the isolation barrier to power the device, either with an isolated DC-DC converter or external PSU. A lot of the off the shelf USB isolators are only good for 100mA.

I have seen one recent reference to a USB2 High Speed isolator but the links to the company and Silicon are dead.
Chris

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Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #151 on: January 06, 2017, 08:52:02 pm »
I recall that early on in this thread there was some discussion on the USB hardware installed, 1.1 vs 2.0, in the I vs non-I variants. Did that ever get resolved ? Are they all USB 1.1 hardware, just that the non-I is missing a couple of ICs ? I believe that sticking to 1.1 speed it's about $20 (US) to make the upgrade.

Yes it was resolved, they both use USB Full Speed (12Mbps) and so are compliant with both USB1.1 and USB2.0 (again at Full speed, not High). The AD USB isolator chip is 'software transparent' so they both use the same driver and on-board code.

Quote
I also sorta recall a comment (perhaps not in this thread) that all the OWON PC scopes push their data to the PC differently from others, and that's why they don't make for good data streamers. That the captured waveform is spit across the USB link as a file ? Even in continuous (vs single shot) mode ?? Does anyone know or am I misfiring a neuron (again) ?

Yes, there's a lot more going on - there's an on board ARM CPU and FPGA rather than just a Cypress 8051 based EZ-USB micro. All the triggering etc is handled on-board rather than having to be done by the PC S/W in real time so all it needs to pump across the interface is display data rather than raw samples.

Yes, you can retrofit the parts, I'm not sure about the current cost. ADUM4160s are relatively easy to source, the more difficult part is probably the TI isolated DC-DC converter IC. I haven't looked for one of those, but reading back a few pages, someone did do it successfully.

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Offline JustMac

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #152 on: January 06, 2017, 09:30:25 pm »
Yes, there's a lot more going on - there's an on board ARM CPU and FPGA rather than just a Cypress 8051 based EZ-USB micro. All the triggering etc is handled on-board rather than having to be done by the PC S/W in real time so all it needs to pump across the interface is display data rather than raw samples.
Aahhh, so am I correct in stating that all you get at the PC end is some "picture" format file for each waveform displayed ? Which at best contains/depicts perhaps 1k samples (given the display box is 1024 max) ? Any and all panning, zooming, measurements, etc is done in the OWON box so, as the old saying goes, "what ya see is what ya get" ?

ETA : Much thanks to you and the others for this very informative thread !   :clap:
« Last Edit: January 06, 2017, 09:32:18 pm by JustMac »
 

Offline gsdn

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #153 on: January 07, 2017, 05:05:19 am »
I ask the above because I have a goofy idea on another way to isolate the scope. My thought was to use a cheap ARM SoC board (perhaps an RPi) to talk via USB to the scope. The pair are powered by the ubiquitous wallwart, which is general isolated from the mains. The link to the client software on the PC is then done via WiFi. This would mean some custom software on the ARM board to play  mailman between WiFi and USB. And some more mods to the client software. I'm sure a real software person (not I) could do it in an hour !  >:D And if the speeds are really 1.1, the additional lag may be unnoticeable. I recall other posters saying it's already somewhat laggy. In return you get isolation and freedom from yet another USB cable dragging across the workbench.

Of course the whole scheme may be goofy but I figured I'd toss it out there and let people pull on it's wings.
It could work. But if you simply use it with a notebook only on its battery, unplugged from the wall, it's also effectively isolated, no? (though not wireless :))
 

Offline JustMac

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #154 on: January 12, 2017, 05:11:41 am »
But if you simply use it with a notebook only on its battery, unplugged from the wall, it's also effectively isolated, no? (though not wireless :))
Yes that would isolate the scope and PC from earth ground. But c'mon now, where's the unneeded complexity in that !   ;)

I got my VDS1022 delivered today. Thumbs up to Saelig, I put the order in on Fri and it came (free shipping) 5 days later.  :-+

I wanted to put up a somewhat obvious chart of sampling rate vs horizontal time setting in case some people didn't realize that they're tied in a DSO. In particular with only 5k samples/chan of storage, there's only so long it can collect data before that memory is full. And so to "see" a longer display means a slower Sa/s rate. And that means less than the full bandwidth is available as those rates.

5ns/div   100MS/s
...
2us/div   100 MS/s
5us/div   50MS/s
10us/div  25MS/s
20us/div  12.5MS/s
50us/div  5MS/s
100us/div 2.5MS/s
200us/div 1.25MS/s
500us/div 0.5MS/s
1ms/div   250kS/s
2ms/div   125kS/s
5ms/div   50kS/s
10ms/div  25kS/s
20ms/div  12.5kS/s
50ms/div  5kS/s
................. trigger to auto mode, no single shot available
100ms/div 2.5kS/s
200ms/div 1.25kS/s
500ms/div 0.5kS/s
1s/div   250S/s
2s/div   125S/s
5s/div   50S/s
10s/div  25S/s
20s/div  12.5S/s ????
50s/div  5S/s
100s/div 2.5S/s  ????

I wonder how Owon splits those half samples ?   ;D

I had a brief chance to sniff the USB link and what I've seen so far is (I think) that the program on the PC sends a set of 3 commands to the scope HW. Each of these gets a 5 byte response except for the last one. If the HW is not "ready" (buffer not full ?) then a "busy" response is sent. IF the HW is ready then there's a 5216 byte message. The 1'st hundred or so bytes seem to be some header of some sort, the remainder appears to be the sampled data.

In this case I had only a single channel on, digitizing the 1kHz test signal. The scope was autoset to some ?? V/div vertically, near zero offset and 50kSa/s. One period of that data looks like ;

3C 3D 3C 3C 3C 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3D 3E 3D
00 01 01 00 00 00 00 00 00 00 00 00 FF FF FF 00 00 FF 00 00 FF 00 00 FF 00

I interpret those 50 bytes as 25 samples of 0 or -1, 25 samples of 61 (+/- 1). The numbers make sense if the scope sends a 2's complement number, -127 to +128 for it's 8 bit sample. The 50 samples make sense for a 1 msec period sampled at 50kSa/s (-> 50 Sa/ms). The 50% DC of the test waveform is obvious.

So sometime this weekend I'll vary the sample rate and turn on the other channel just to see what I can see via the sniffed USB. I'll post my results and thoughts here, if anyone is interested and the OP doesn't mind the "hijack" of his thread. And if I can how to get the multiport to output, I'll measure the waveforms/sec update rate vs horz time setting, which should be good for a laugh. From the USB timestamps for the above, it was ~ 14 ms between 2 full data packets or ~71 wvfrms/s.
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #155 on: January 12, 2017, 10:37:05 am »
Quote
So sometime this weekend I'll vary the sample rate and turn on the other channel just to see what I can see via the sniffed USB. I'll post my results and thoughts here, if anyone is interested and the OP doesn't mind the "hijack" of his thread. And if I can how to get the multiport to output, I'll measure the waveforms/sec update rate vs horz time setting, which should be good for a laugh. From the USB timestamps for the above, it was ~ 14 ms between 2 full data packets or ~71 wvfrms/s.

Go ahead and hijack  :), I don't think anyone has done any USB sniffing yet (one advantage is that the USB connection is slow enough to do it). With the Mac and Linux efforts going on too, all additional info is useful.

P.S. Another line of interest is the documented SCPI protocol interface.

http://www.owon.com.hk/service_down.asp?SortID_1=4&SortID_2=7&seek=&curpage=3
« Last Edit: January 12, 2017, 10:45:55 am by Gyro »
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Offline common_ground

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #156 on: February 05, 2017, 03:56:29 pm »
Is the noise level on the 1022 much higher than the noise on 1022I oscilloscope ( if someone was able to check both ).
Thank you.
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #157 on: February 06, 2017, 01:23:57 pm »
I don't think this is a question that anyone will be able to answer., there are too many variables. The 1022 isn't inherently noisier than the USB isolated version (if you just short the inputs I think the residual noise would be the same). Any additional noise will come from ground loops. The noise induced by a ground loop will be dependent on the test setup, the computer, the length of USB and mains connections, how quiet the mains is etc. The VDS1022I will probably be quieter in some situations by some degree but it is not possible to quantify it so easily.

What the USB isolation mostly brings you is reduced chance of damage to your PC and equipment due to accidentally created ground currents, eg. accidentally shorting a probe ground clip to a high current supply rail (note that it doesn't mean that 'floating' the scope's ground at an elevated voltage is a good idea though).
Chris

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Offline krum

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #158 on: February 06, 2017, 08:16:20 pm »
Hello everyone,
I am reading this forum for some time and it is a real pleasure, although probably 80% of the things I am reading, are very distant or not clear to me. I have a little to no electronic experience, but how you guys approach each challenge, is a pleasure to read. 

Because of this, topic I recently purchased an OWON VDS1022I oscilloscope. I intend to learn how to use it for measuring things around my oldtimer (which recently received a brain surgery and now features megasquirt).

I hope my cry for help is on the right place. Today I was testing the oscilloscope for the first time for about 30-40 minutes, then turned it off and after turning it on again, it won't set itself automatically (the big A letter on the top right corner).
The program opens the AutoSetting dialog, the oscilloscope clicks twice and then the AutoSetting dialog stays just forever. The oscilloscope light is green and every few seconds it blinks shortly red.

Has anyone experienced such issue? Would it be possible, that I am not doing anything correct? I already deinstalled and reinstalled everything on my laptop, and also tested the oscilloscope on another laptop.

Thanks in advance for any help you could provide
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #159 on: February 07, 2017, 10:43:52 am »
Hi krum, welcome to the forum.

You say that the Autoset has stopped working.  Does manual setting of timebase and sensitivity range of the inputs still work correctly? Do you still get sensible traces if you adjust these settings manually? Do all ranges work, AC/DC coupling too.

If it works with manual settings then it sounds unlikely that there is a hardware fault. If you have tested on two different laptops then it probably rules out USB interface problems too (unless both laptops cannot supply enough power to drive the scope, that seems unlikely though). You are using the supplied cable rather than a longer one? If the scope is responding, it seems to rule out driver issues -the S/W would tell you if it couldn't see the scope anyway.

If you see traces in manual mode then I'm wondering if there is something about the signal(s) that is confusing the Auto setup (I don't know maybe large spikes or something). If there is a fault on one of the sensitivity ranges then I suppose that could confuse it too.

The other thing to check is that you are running the latest version of the PC software, which is not necessarily what is on the CD, depending how long the supplier had it in storage. I have vague memory of one of the past updates being to improve autoset functionality.

You can find the latest software on the OWON site: http://www.owon.com.hk/products_info.asp?ProID=175   It's the first thing Owon would tell you to do anyway.

If nothing helps, then it's possible that you have a faulty unit, i which case I would go back to the supplier. Owon might also be able to help based on its behaviour (light pattern etc).

I hope this helps.


P.S. It probably doesn't help right now, but it's a good thing to get into the habit of using the manual settings, based on what you are expecting the signal to be, rather than autoset. It gives to a better 'feel' for a signal not being what it should and you can probably set the scope more optimally by eye too.
Chris

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Offline krum

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #160 on: February 07, 2017, 11:20:31 pm »
Thank you for the fast response and good advises, Chris.
To answer first to the setup questions - I am using the supplied USB cable, tried both plugging it in 1 and 2 usbs (it is an Y cable).
When default settings are restored I cannot see any traces in manual mode (good tip, will use it, thanks).
Software is 1.0.23 (latest from Owon's website). I have also tried with 1.0.24, which came with the oscilloscope on a CD.

I have dug a bit more in the menus and found the "Self Cal" button under Utility. After the calibration finishes, I can see traces, when I connect the probe to the generator. The frequency is measured at 1000Hz.
When the scale is at <5V, the graphic seems to be not effected by changing the scale. The Voltage cursor however changes its value. The graphic is rather tiny. If I change the probe's multiplier to  1X, then the graphic gets much higher.
Changing the scale to 5V and more reduces the size of the graphic to a very tiny one.

Following your advise, I have contacted the supplier and prepared this video for them:  https://youtu.be/9Yw15jdur5g
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #161 on: February 08, 2017, 01:11:08 pm »
You're welcome, I'm glad it was of some help anyway.

Quote
When the scale is at <5V, the graphic seems to be not effected by changing the scale. The Voltage cursor however changes its value. The graphic is rather tiny. If I change the probe's multiplier to  1X, then the graphic gets much higher.
Changing the scale to 5V and more reduces the size of the graphic to a very tiny one.

Hmm, that looks like the problem then, no wonder the Autoset is getting confused. At a guess it's a bad joint somewhere between the processor and the variable gain amplifier (it sound as if the relay controls work) but best not to mess with it while you're in discussion with the supplier, who will hopefully be helpful!

One thing I forgot to ask... Does it behave the same on the other channel? That would be helpful to know, both for diagnosis and for evidence to the supplier.


P.S. I wonder what they've changed in s/w 1.0.24 vs the website version. Unfortunately Owon don't really do release notes.  :(
« Last Edit: February 08, 2017, 01:13:45 pm by Gyro »
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Offline krum

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #162 on: February 09, 2017, 09:01:24 pm »
Both channels act exactly the same. I expect the seller to act soon, but let's see what will happen...

If you are interested of taking a look on 1.0.24, I can try to upload it somewhere in the cloud.
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #163 on: February 09, 2017, 10:13:16 pm »
Now that's really strange, one channel is reasonably easy to explain as a simple hardware fault, both channels is much harder!

Just one other thing from looking through the menus - you haven't got the probe divide ratio (Function menu > Channel > Probe Rate) set to something silly like X1000? I think I'm out of ideas.

I hope the supplier comes back to you soon.

Yes, it would be interesting to see if I can see any differences in 1.0.24. Thank you!
« Last Edit: February 09, 2017, 10:16:03 pm by Gyro »
Chris

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Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #164 on: February 10, 2017, 10:41:03 am »
Ok, just one more thought overnight (can you tell it's bugging me?  :)).

Do a full uninstall of 1.0.24, then check that the installation folder is empty / deleted (just in case it has left some settings file). Then do a clean install of 1.0.23 from the website. I'm not sure if this is what you did anyway, or whether you installed 1.0.23 over the top of 1.0.24.

After that it has to be a faulty unit.
« Last Edit: February 10, 2017, 10:48:01 am by Gyro »
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Offline Ultrawipf

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #165 on: February 10, 2017, 12:07:37 pm »
The autoset does not really work most of the time for me too but my scope is definetly not faulty. I guess it is just terrible software.
For me the led flashing pattern is slow blinking red/green when the scope is not initialized and mostly constant green with short red pulses while running so that should be correct.

Maybe do a self calibration and software reset again but i guess something is definetly wrong with you scope when the traces are super high in the 50V setting if i saw that correctly in the video.
If everything fails contact the seller and get a replacement.
 

Offline krum

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #166 on: February 12, 2017, 09:32:09 pm »
Thanks Gyro,  Ultrawipf.
The probes divider was set to 10x initially. I did the deinstall/reinstall on the first laptop and I installed 1.0.23 clean on the second laptop. The behavior of the both channels is the same.

Ultrawipf, now that you have pointed it out, it really looks like the signal is too high.

Well... apparently the unit is defect. Shame, I was willing to setup my newly implanted VR sensor on my oldtimer. Now I will have to wait until the seller responds. Tomorrow evening I will check with them what's going on.
 

Offline ivanlrlukic

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #167 on: February 14, 2017, 03:13:02 pm »
I'be purchased VDS1022 after reading rather positive reviews of it on this forum.

Tried it on Win7 machine and it works OK. Then I tried to install it on dedicated PC that runs XP but without success. Installation simply won't start with error message that says nothing usable. SW version that arrived with device on CD is 1.0.23, the same as on on their site.

I guess XP is (or was) supported since there is official description how to install USB driver for 2000/XP.

Does anybody have, and is willing to share (via drivespace, or...) an older version of SW that supports XP?

Regards, Ivan.
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #168 on: February 15, 2017, 06:23:12 pm »
Hi Ivan,

Welcome.

That's curious, I have two XP (SP3) PCs running the latest 1.0.23 version from the website. What was the error message?
Chris

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Offline ivanlrlukic

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #169 on: February 16, 2017, 08:43:56 am »
Hi Gyro,

it's XP SP3, with 3 GB RAM and 100 GB of free HD space.

AVG AV program disabled.

Error message appears just after installation start, find it attached.

Regards, Ivan.

 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #170 on: February 16, 2017, 12:18:12 pm »
Hi Ivan,

Not such an unusable error message then. Looking on the web, it indicates that the open source installer they use has detected a checksum error in the file:

http://nsis.sourceforge.net/Why_do_I_get_NSIS_Error%3F

At a guess, it's something to do with what you used to unpack the installer .exe file from the downloaded .rar file from the website. I downloaded the 1.0.23 file from the website this morning (Edit: on my XP machine), unpacked it using 7Zip and the installer opened fine.

Your other alternative would be to copy the installer file that you unpacked on your Win7 machine across to your XP machines, because it worked there.

The other thing the page above suggested was the possiblity of virus on the system. I would re-enable your AVG.

Chris


P.S. Just as a precaution, I just scanned the installer exe file itself with AVG2017 and Malwarebytes and according to them it's clean.
« Last Edit: February 16, 2017, 12:48:05 pm by Gyro »
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Offline krum

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #171 on: February 17, 2017, 05:08:44 pm »
Hi,
a short update, which could be helpful for the future buyers of this oscilloscope. The seller agreed to send a new device. According to him, it will take 8-16 working days to arrive.
He rejected the old device, as the return costs will be too high.

I guess this leaves me with a device to play... Any ideas what and how to check are very welcome. After a surface check nothing looks burned or unsoldered.
 

Offline ivanlrlukic

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #172 on: February 17, 2017, 05:19:23 pm »
At a guess, it's something to do with what you used to unpack the installer .exe file from the downloaded .rar file from the website. I downloaded the 1.0.23 file from the website this morning (Edit: on my XP machine), unpacked it using 7Zip and the installer opened fine.

Chris, you,ve been right on-topic.

Archive was unpacked on XP and everything worked fine since!

Many thanks!
 

Online Gyro

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #173 on: February 17, 2017, 07:20:53 pm »
Well that was a pretty good day then!  :)

@ivanlrlukic:  My pleasure, glad you got it sorted. Mine runs nicely on what is really quite an old XP machine now. Thanks for reporting back.  :-+

@krum:
That sounds like a result too! Make sure you keep an eye on the arrival date just in case it takes you outside ebay or whatever complaint date (I'm sure it will be fine though). An interesting unit to investigate, it was puzzling from the start, I don't think anyone has seen anything like that before, on here anyway.

I wondered about bad firmware, but I'm not sure if there is anything, I think it and the FPGA data all get downloaded over USB at startup... and the PC correcty recognises it and performs most operations correctly anyway.

Looking back to the original teardown, I would download the datasheet for the AD603 variable gain amplifiers and look carefully at the control signals, I still can't see why it would affect both channels though. If we look at it as an production fault though, I would suspect the soldering of the SiM3U156 CPU, maybe the gain control pins are adjacent on a badly soldered side. Maybe also look for missing passives, check against the photos that Mark_O posted as his board revision was later than mine. It would be worth posting some photos, we might be able to spot something (yours might be a later revision too, which would be interesting).

Do please post back on anything you find regardless, getting it going too would be a nice result!
Chris

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Offline CatWhisker

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Re: OWON VDS1022I Quick Teardown (versus the Hantek 6022be)
« Reply #174 on: February 21, 2017, 11:09:09 am »
Been faffing in Linux all day.
I'm at the point where the app will recognise the device, but fails (times out) at sending config.
This is the point I got too, before testing in the Mac. If you look at dmesg output, there should be a few "USBDEVFS_CONTROL failed" messages.
Ah, useful - didn't think to check dmesg!

It should have write access and a quick Python script succeeds, but this is just annoying!
What does your Python script do?
I've completely forgot - I don't even remember writing said script now.
I think it was purely a quick way to init and poke at the scope.

The provided libusbJava.so is built for 32bit systems, are you using a 64bit system?

So far, apart from the Mac, in which we already know it works, I've tried:
1) a 64bit Linux (Arch) system with a recent kernel: timeout errors ("USBDEVFS_CONTROL failed ...") early in the device initialization progress.
2) a 32bit Linux (Centos) with an old (2.6) kernel running inside Virtualbox with the USB device passed through to the guest: same as 1).
3) a 64bit FreeBSD 11 running inside Virtualbox with the USB device passed through to the guest: didn't work, then worked 1 or 2 times, then never again; even not working, it gets further in the device initialization progress than Linux, the last message shown in the terminal, before stalling, is "+6250 bytes MCU:getFrame 14".
4) same 64bit FreeBSD 11 system running on actual hardware: same results as 3).

I have no idea what made it work once (or twice) in FreeBSD, but it did. it seems this device has some weird USB behavior... after trying to use it in FreeBSD/Linux, it locks the boot process of my notebook (which proceeds promptly after unplugging the device), booting with it plugged in sometimes also prevents Linux from recognizing my wireless keyboard/mouse usb receiver (which also proceeds to work promptly after unplugging it)...

I 'think' I was swapping libusbJava.so for a suitable blob. (As per OS X)
I'd probably guess that the USB implementation on BSD is more forgiving or on-spec than the Linux implementation - closer to the OS X version.
Getting a FreeBSD driver based off the OS X method may be more likely to work?

When it worked 2-3 times, was this concurrent? Or through power cycles (scope unplugged)?
 


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