STM32L496 USB error Topic is solved

[lilvinz]

Could this also be caused by faulty hardware e.g. bad usb signalling? Does it make sense to investigate in that direction e.g. check the signals and make a trace using a usb protocol analyzer?

[Giovanni]

I don't know, I need to try first.

My idea is that the OTG on L4 is misbehaving for some reason, interrupts are out of logic order, maybe this is another instance of the problem fixed earlier.

Giovanni

[lilvinz]

Attached you will find a screenshot from sigroc logic analyzer as well as from my scope.
It looks like after the data0 of the setup there is garbage on the line.
I can't tell if this is caused by the peripheral not doing the right thing or a hardware problem.

Here its "SYNC ERR" to the right:

Here its in the middle of the screenshot:

Other than that garbage, the signals looks good to me.

Cheers

Vinz

[steved]

Can I suggest you set up the scope to look at those signals in differential mode? That way you'll have a better idea of the actual logic levels seen by the CPU. It may be that the data is always one or zero; or maybe there are edges which cause the data to be misinterpreted.

[lilvinz]

Can I suggest you set up the scope to look at those signals in differential mode? That way you'll have a better idea of the actual logic levels seen by the CPU. It may be that the data is always one or zero; or maybe there are edges which cause the data to be misinterpreted.

Hi Steved,

thanks for the hint. At this point i don't think it is worth the effort though.
I tend to agree with Giovanni that this is probably another issue between the driver and the usb peripheral.
Once this has been verified / disproved i will do more measurements.

Cheers

Vinz

[lilvinz]

Hi Giovanni,

I have bought a nucleo board and tried to reproduce the problem there without result.
In the end it was an issue with my hardware.

Thanks for your time!

Vinz

[Giovanni]

Same other conditions? (FW, host, cables, lunar phase?)

Giovanni

[Giovanni]

Closing then.

Giovanni