What is happening with this USB?

[FreshmanNewbie]

I am using this USB Hub.

And in one of the downstream port, I am getting this type of waveform.

Any idea on why and how this happens?

Yellow is VBUS.

Blue is D+ and Green is D-.

 

[KlausST]

Hi,

the picutre takes ages to load. Too long for me to answer.
I don´t know what file size it is, but I´m sure it could be as small as 50kBytes without losing thread related informations.

Klaus

 

[barry]

looks like you’re picking up noise, but it doesn’t appear to be a problem since it’s not driving the signal below the logic threshold.

On second look, this doesn’t make sense. D+/D- are differential, the signals you’re showing are not. Maybe a cable problem.

 

[FvM]

Unclear if the measurement can be related to defined operation of the USB port. If not, what's your concern?

 

[D.A.(Tony)Stewart]

Hi,

the picture takes ages to load. Too long for me to answer.


Klaus

Are you still on dial-up? 585 Mbps here.

@FreshmanNewbie It loops like Vcm DC is OK just offset traces and SMPS common mode noise and maybe aliasing with undersampling capture error of same.

If there are SMPS on each end , also examine ground currents and floating DC source, consider SMD BALUN or ferrite clamps or PE gnd.

 

[KlausST]

Hi,

Are you still on dial-up? 585 Mbps here.

Not dial up, but 50MBits/s ... but it took at least 20 boring seconds.
A speed test showed more then 45MBits/s. I´m not sure where the bottleneck is.

An easy to use online tool generates this: 1606 kBytes --> 48 kBytes

The original was a photo, but converted to .PNG. .. which does not work well.

Do this:
* Screenshot --> .PNG
* Photo --> .JPG

not the other way round.

Klaus

 

[D.A.(Tony)Stewart]

Hi,


Not dial up, but 50MBits/s ... but it took at least 20 boring seconds.
A speed test showed more then 45MBits/s. I´m not sure where the bottleneck is.

An easy to use online tool generates this: 1606 kBytes --> 48 kBytes
View attachment 188907

The original was a photo, but converted to .PNG. .. which does not work well.

Do this:
* Screenshot --> .PNG
* Photo --> .JPG

not the other way round.

Klaus

I got this reply in a flash. Something is wrong. Win10 Edge is memory hog. I prefer Win7. much faster. You may msg me if you want help on PC

I just checked a screen partial copy which when pasted was a bitmap, BMP = 4 MB then EDAboard site converts to PNG with high quality and only 25% compression to 3MB whereas JPG low quality after Save AS .jpg, then add image, find file and paste takes me more about 20 seconds too, unless I just had coffee. I can set the target file size to anything but 50k, I agree is perfect, if one does not need to zoom.

Perhaps someone reading this can request EDA to fix that conversion process to save memory and time.