[SI-LIST] AW: Board Hangs due to Cable contact
- From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
- To: "vinod ah" <ah.vinod@xxxxxxxxx>
- Date: Wed, 28 Nov 2012 11:52:50 +0000
Vinod,
you could try to short out ac voltages that connect tot he connector shield.
place a capacitor between GND and VCC as close to the connector as possible.
The effect could also be a sign, that some driver (maybe the USB driver?) is
facing PDN problems. Can you monitor any chip inputs while connecting to the
USB cable?
BR
Gert
Besuchen Sie uns auf der SPS/IPC/Drives 2012 vom 27. - 29. November 2012 in
Nürnberg, in Halle 10 am Stand 140.
----------------------------------------
Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339 Espelkamp;
Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB 8808;
Vertretungsberechtige Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
Dipl.-Ing. Torsten Ratzmann, Dr.-Ing. Alexander Rost
-----Ursprüngliche Nachricht-----
Von: vinod ah [mailto:ah.vinod@xxxxxxxxx]
Gesendet: Mittwoch, 28. November 2012 12:44
An: Havermann, Gert
Cc: SI-LIST
Betreff: Re: [SI-LIST] Board Hangs due to Cable contact
Hi,
I measured the waveform on the Harddisk usb cable shield without connecting to
the board. What i see is, there is ac voltage of 50Hz is seen on the USB cable
shield !!!. So there is some leakage happening from the ac-dc adapter which
powers the hard disk. Nothing was observed on the board ground, implying there
is no leakage in ac-dc adapter powering the tablet board.
But my question is when this hard disk USB cable is connected to board, will it
cause a ground bounce instantaneously to make the board hang? If this can cause
a board hang, how can i go about solving this issue of system hang in board as
hard disks are from external vendors, so i have no control..
Regards
Vinod A H
On Tue, Nov 27, 2012 at 5:21 PM, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>
wrote:
> Vinod,
>
> this just means that most of the voltage you measured is incductively coupled
> into the one of the GND Levels of the Tablet or HDD. Take a scope shot of the
> voltage to find the shape and frequency, This will give further insight into
> the source. Could be a clock signal, or switching noise from one of the power
> supplies or anything. If you find the frequency and signal shape, you just
> need to check the tablets schematic to find the root of that signal, and then
> check the PCB Layout to find out where the coupling might happen.
>
> BR
> Gert
>
>
>
> Besuchen Sie uns auf der SPS/IPC/Drives 2012 vom 27. - 29. November 2012 in
> Nürnberg, in Halle 10 am Stand 140.
>
>
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.:
> HRB 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm.
> Edgar-Peter Düning, Dipl.-Ing. Torsten Ratzmann, Dr.-Ing. Alexander
> Rost
>
> -----Ursprüngliche Nachricht-----
> Von: vinod ah [mailto:ah.vinod@xxxxxxxxx]
> Gesendet: Dienstag, 27. November 2012 11:59
> An: Havermann, Gert
> Betreff: Re: [SI-LIST] Board Hangs due to Cable contact
>
> Hi,
>
> With 2 K ohms across voltmeter the reading is 0.4V while without 2K
> ohms it is 90V in ac mode. So what does this actually indicate? I am
> very new to power domain, so struggling a bit to solve issues
>
> On Tue, Nov 27, 2012 at 3:41 PM, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>
> wrote:
>> Vinod,
>>
>> also test with a 2kOhm load connected in parallel to the voltmeter. This
>> will delete the inductively coupled voltages, and will give you some insight
>> about where this voltage is coming from.
>>
>> BR
>> Gert
>>
>>
>>
>> Besuchen Sie uns auf der SPS/IPC/Drives 2012 vom 27. - 29. November 2012 in
>> Nürnberg, in Halle 10 am Stand 140.
>>
>>
>> ----------------------------------------
>> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
>> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.:
>> HRB 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm.
>> Edgar-Peter Düning, Dipl.-Ing. Torsten Ratzmann, Dr.-Ing. Alexander
>> Rost
>>
>> -----Ursprüngliche Nachricht-----
>> Von: vinod ah [mailto:ah.vinod@xxxxxxxxx]
>> Gesendet: Dienstag, 27. November 2012 11:07
>> An: Havermann, Gert
>> Betreff: Re: [SI-LIST] Board Hangs due to Cable contact
>>
>> Hi,
>>
>> When i measure the voltage between the HDMI connector shield on-board and
>> the USB hard disk cable (no contact between the two, but both are powered),
>> i see a 90V in multimeter in ac mode, 0.02V in DC mode. I am not sure
>> whether i should be measuring in ac mode for ground voltage difference
>> between HDMi connector on-board and USB cable ground.
>> Also not sure why the multimeter is showing 90V in ac mode.
>>
>> All the AC supply i am using is 230V
>>
>> Regards
>> Vinod A H
>>
>> On Tue, Nov 27, 2012 at 1:11 PM, Havermann, Gert
>> <Gert.Havermann@xxxxxxxxxxx> wrote:
>>> Hi Vinod,
>>>
>>> sounds like a problem with GND potentials. Have you measured the voltage
>>> between USB connector and cable with and without Load (the load can be a
>>> 2kOhm Resistor in parallel to the Voltmeter)? The USB connector should be
>>> decoupled from Power GND.
>>>
>>> BR
>>> Gert
>>>
>>>
>>>
>>> Besuchen Sie uns auf der SPS/IPC/Drives 2012 vom 27. - 29. November 2012
>>> in Nürnberg, in Halle 10 am Stand 140.
>>>
>>>
>>> ----------------------------------------
>>> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
>>> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.:
>>> HRB 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm.
>>> Edgar-Peter Düning, Dipl.-Ing. Torsten Ratzmann, Dr.-Ing. Alexander
>>> Rost
>>>
>>> -----Ursprüngliche Nachricht-----
>>> Von: si-list-bounce@xxxxxxxxxxxxx
>>> [mailto:si-list-bounce@xxxxxxxxxxxxx] Im Auftrag von vinod ah
>>> Gesendet: Dienstag, 27. November 2012 08:28
>>> An: SI-LIST
>>> Betreff: [SI-LIST] Board Hangs due to Cable contact
>>>
>>> Hi all,
>>>
>>> I am currently debugging a tablet board where i am facing an issue of board
>>> operating system hanging due to probably ground bounce.
>>>
>>> The board has USB and HDMI connector and when ever a self powered hard disk
>>> with USB cable is touched (USB connector of hardisk touching the connector
>>> on-board) to the HDMI connector shield or USB connector shield i am seeing
>>> the OS hangs. I am suspecting an ground bounce due to physical contact of
>>> USB cable ground with board ground.
>>>
>>> The issue is not seen when a bus powered USB hard disk cable is touched to
>>> the connectors. Initially thought it might be an ESD issue, but after not
>>> able to reproduce the issue with bus powered hard disk usb cable, i am
>>> stuck with no solution !!!
>>>
>>> The power to the self powered hard disk is provided by a 2 pin adapter
>>> which gets connected to 230V AC source.
>>>
>>> Regards
>>> Vinod A H
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>>
>
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