When we discharged the ESD into either USB shell (positioned at the edge of the enclosure as previously described) the beagle reset (more often that not). We believe we have now fixed that particular issue by solidly grounding the USB shell to the enclosure at the point of entry. A mechanical fix. There are other parts of the units that are metal and would be touched by the end user. Some of these are also susceptible to the ESD. We are going through a process of grounding these but this sometimes seems to make things worse! If by ground plane you mean on the enclosure rather than at the PCB level then yes there are holes in the ground plane, by necessity due to the mechanical design of the enclosure. We have previously assessed the unit for emissions and are up around the limit in the region of 160MHz to 180MHz. We have not yet investigated the cause of that. Thank you for your help John, much appreciated. Any further advice welcomed...
Regards, Lee. On Tuesday, 6 January 2015 21:17:47 UTC, john3909 wrote: > > > From: <[email protected] <javascript:>> > Reply-To: "[email protected] <javascript:>" < > [email protected] <javascript:>> > Date: Monday, January 5, 2015 at 1:41 AM > To: "[email protected] <javascript:>" <[email protected] > <javascript:>> > Subject: Re: [beagleboard] CE and ESD, BBB is failing 4kV contact > discharge ESD testing > > To give further background... > > The BBB is positioned centrally at the front of a relatively large > enclosure. It is connected to a display/touchscreen which are also > situated in the same area. > > The USB I/O is brought out of the enclosure at the side of the unit via > USB cables and another PCB. Both of the BBB USB connectors are connected > within the enclosure by their own USB cable to a PCB of my own design. > > This PCB sits at the internal side face of the enclosure and provides > access to USB Connectors from the outside world. > > On this PCB I have designed-in a Wurth Electronics ESD solution. This > solution is documented in the PDF (titled: USB Port Protection) at this > link: > > > http://www.we-online.de/web/en/electronic_components/produkte_pb/application_notes/robustes_design_von_usb_anwendungen.php > > The solution I have implemented is described in the document as "Double > protection of single USB port" on page 7. > > Any further comments welcome... > > So what happens when you discharge the ESD probe? Are you probing the USB > connector case, pins, etc? I’m guessing the board either resets or hangs? > This could be a grounding issue or an antenna issue; either way, you have > to use a process of elimination to determine which. Best way to determine > if it is an antenna issue, start by looking for radiated signals (you need > a RF probe with a spectrum analyzer). If you don’t have the required > equipment, your local university is always a great resource. EMI and EMC > are really two sides of the same coin. If a signal radiates at a certain > frequency, then it is also susceptible to those same frequencies. For > grounding, it depends on how good your ground plane is and whether you have > holes in your ground plane. > > Regards, > John > > > > On Wednesday, 24 December 2014 02:07:41 UTC, john3909 wrote: >> >> >> On 12/23/14, 4:58 PM, "Chris Morgan" <[email protected]> wrote: >> >> >How is your esd protection designed at the usb connections, or are you >> >hitting the usb connectors right on the bbb? Would need a lot more >> >details about exactly how the system was being built and where you are >> >discharging to know what might be going on. I'm guessing your esd >> >protection may not be getting to a solid enough chassis ground close >> >enough to the connector that is being hit. >> Actually, from what I recall, the USB protection isn¹t in the right >> place. >> The correct layout is USB connector, ESD protection and then USB >> transceiver. However, in the BBB, the USB connector is connected to the >> USB transceiver and the ESD protection is on the other side of the USB >> connector. Granted, the distance is small and may even work correctly, >> but >> this layout doesn¹t follow good ESD layout principles. >> >> Regards, >> John >> > >> >Chris >> > >> > >> > >> >On Tue, Dec 23, 2014 at 6:40 AM, <[email protected]> wrote: >> >> Thanks for the prompt response Gerald. >> >> >> >> The beagle has been designed into a system which is in a plastic and >> >>metal >> >> enclosure. The only I/O it has to the outside (other than >> touchscreen) >> >>is 2 >> >> USB connections. >> >> >> >> These connections are what are prone to the 4kv ESD. A discharge on >> the >> >> shell of the USB connector causes the micro to reset. This occurs >> even >> >> though ESD suppression has been designed in at the USB connectors. >> >> >> >> The micro seems particularly prone to this phenomenon. ESD is an >> >>awkward >> >> problem to solve, there isn't one solution to fit all and things such >> as >> >> enclosure design can have an influence... >> >> >> >> On Monday, 22 December 2014 19:42:37 UTC, Gerald wrote: >> >>> >> >>> I am not sure what was used, other than putting it in a box or adding >> >>>ESD >> >>> protection devices on every point on the board likely to be touched >> by >> >>>a >> >>> person. >> >>> >> >>> The certification was done by a lab. You are welcome to download the >> >>>full >> >>> report from the WIKI. >> >>> >> >>> http://www.elinux.org/Beagleboard:BeagleBoneBlack >> >>> >> >>> Gerald >> >>> >> >>> >> >>> On Mon, Dec 22, 2014 at 7:57 AM, <[email protected]> >> wrote: >> >>>> >> >>>> Hi Guys, I am seeing the same issue as Richard above. Was a >> solution >> >>>> ever found for this ESD reset issue? >> >>>> >> >>>> In the past I have had some success on solving this issue on other >> >>>>micros >> >>>> by adding some capacitance on the micro's reset line to prevent the >> >>>>reset >> >>>> I/P bouncing when the ESD takes place, however looking at the BBB >> >>>> schematics, this is already included in the form of C24 being 1uF. >> >>>> >> >>>> Richard, did you find a solution to this? >> >>>> >> >>>> Gerald, I assume this family of processors must be used in many >> >>>> commercial products. Do you have an idea of what solutions were >> used >> >>>>to >> >>>> overcome this? >> >>>> >> >>>> Many thanks in advance. >> >>>> Lee. >> >>>> >> >>>> On Friday, 1 August 2014 18:57:39 UTC+1, Gerald wrote: >> >>>>> >> >>>>> CE testing that was does not cover ESD testing. This board has >> never >> >>>>> been tested for ESD. >> >>>>> >> >>>>> Gerald >> >>>>> >> >>>>> >> >>>>> >> >>>>> On Fri, Aug 1, 2014 at 12:21 PM, Richard Ketcham >> >>>>><[email protected]> >> >>>>> wrote: >> >>>>>> >> >>>>>> Hello, >> >>>>>> >> >>>>>> I'm interested in CE testing a device which includes the BBB. In >> >>>>>>order >> >>>>>> to determine if the device will pass, I've been shocking it with >> an >> >>>>>>ESD gun >> >>>>>> (both contact and discharge). I have been running into an issue >> >>>>>>where when >> >>>>>> I shock the ground plane with a 4kV contact discharge, the BBB >> >>>>>>Ethernet >> >>>>>> becomes unresponsive and does not recover until I cycle the power. >> >>>>>>I've >> >>>>>> tried this test with only the BBB and it reacts the same way. I >> see >> >>>>>>there's >> >>>>>> a CE certification which says it passes 4kV contact discharge, but >> >>>>>>I've been >> >>>>>> unable to replicate it. >> >>>>>> >> >>>>>> >> >>>>>> Are there caveats to the CE certification which the BBB has >> >>>>>>relating to >> >>>>>> ESD testing? >> >>>>>> Is this a self certification? >> >>>>>> Do you have any suggestions on how mitigate this problem? >> >>>>>> >> >>>>>> I will appreciate any information you can provide on this problem. >> >>>>>> Thanks, >> >>>>>> Rich >> >>>>>> >> >>>>>> -- >> >>>>>> For more options, visit http://beagleboard.org/discuss >> >>>>>> --- >> >>>>>> You received this message because you are subscribed to the Google >> >>>>>> Groups "BeagleBoard" group. >> >>>>>> To unsubscribe from this group and stop receiving emails from it, >> >>>>>>send >> >>>>>> an email to [email protected]. >> >>>>>> For more options, visit https://groups.google.com/d/optout. >> >>>>> >> >>>>> >> >>>> -- >> >>>> For more options, visit http://beagleboard.org/discuss >> >>>> --- >> >>>> You received this message because you are subscribed to the Google >> >>>>Groups >> >>>> "BeagleBoard" group. >> >>>> To unsubscribe from this group and stop receiving emails from it, >> >>>>send an >> >>>> email to [email protected]. >> >>>> For more options, visit https://groups.google.com/d/optout. >> >>> >> >>> >> >>> >> >>> >> >>> -- >> >>> Gerald >> >>> >> >>> [email protected] >> >>> http://beagleboard.org/ >> >>> http://circuitco.com/support/ >> >> >> >> -- >> >> For more options, visit http://beagleboard.org/discuss >> >> --- >> >> You received this message because you are subscribed to the Google >> >>Groups >> >> "BeagleBoard" group. >> >> To unsubscribe from this group and stop receiving emails from it, send >> >>an >> >> email to [email protected]. >> >> For more options, visit https://groups.google.com/d/optout. >> > >> >-- >> >For more options, visit http://beagleboard.org/discuss >> >--- >> >You received this message because you are subscribed to the Google >> Groups >> >"BeagleBoard" group. >> >To unsubscribe from this group and stop receiving emails from it, send >> an >> >email to [email protected]. >> >For more options, visit https://groups.google.com/d/optout. >> >> >> -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > For more options, visit https://groups.google.com/d/optout. > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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