Reply-To: "William LenihanIii" From: "William LenihanIii" Newsgroups: comp.arch.fpga Subject: Unused Pins on big Virtex-II Lines: 9 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Message-ID: <5V_Wa.31676$Mc.2501134@newsread1.prod.itd.earthlink.net> Date: Sun, 03 Aug 2003 03:00:17 GMT NNTP-Posting-Host: 216.244.27.28 X-Complaints-To: abuse@earthlink.net X-Trace: newsread1.prod.itd.earthlink.net 1059879617 216.244.27.28 (Sat, 02 Aug 2003 20:00:17 PDT) NNTP-Posting-Date: Sat, 02 Aug 2003 20:00:17 PDT Organization: EarthLink Inc. -- http://www.EarthLink.net Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!irazu.switch.ch!switch.ch!news.tele.dk!news.tele.dk!small.news.tele.dk!newsfeed.news2me.com!elnk-nf2-pas!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread1.prod.itd.earthlink.net.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:31469 We will be designing with a large (xc2v6000) Virtex-II part in a ball-grid array package that has maybe ~1000 balls, but we are using fairly few (~250) "mission logic" I/O. Add in power & ground, configuration, etc., we will have 100's of general-purpose I/O balls that are not needed. What should we do with them? Ground them? Let them float? If we can let them float, do we even need a solder pad on the PWB for them to "land on"? ###### From: Andrew Paule User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.arch.fpga Subject: Re: Unused Pins on big Virtex-II References: <5V_Wa.31676$Mc.2501134@newsread1.prod.itd.earthlink.net> In-Reply-To: <5V_Wa.31676$Mc.2501134@newsread1.prod.itd.earthlink.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Lines: 23 Message-ID: Date: Sun, 03 Aug 2003 00:11:07 -0500 NNTP-Posting-Host: 63.229.198.65 X-Trace: news.uswest.net 1059887284 63.229.198.65 (Sun, 03 Aug 2003 00:08:04 CDT) NNTP-Posting-Date: Sun, 03 Aug 2003 00:08:04 CDT Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.news2me.com!newsfeed2.easynews.com!newsfeed1.easynews.com!easynews.com!easynews!feed.news.qwest.net!news.uswest.net.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:31472 Don't assign 'em - should do fine - they'll float. A solder pad is a good idea because these things come balled, and the solder will just float around and find something to connect to (most likely a nearby ball and give you a bridge - bit**) if you don't - talk to your assembly house. Andrew William LenihanIii wrote: >We will be designing with a large (xc2v6000) Virtex-II part in a ball-grid >array package that has maybe ~1000 balls, but we are using fairly few (~250) >"mission logic" I/O. Add in power & ground, configuration, etc., we will >have 100's of general-purpose I/O balls that are not needed. > >What should we do with them? Ground them? Let them float? If we can let them >float, do we even need a solder pad on the PWB for them to "land on"? > > > > ###### NNTP-Posting-Date: Sun, 03 Aug 2003 09:44:58 -0500 Date: Sun, 03 Aug 2003 10:46:19 -0400 From: Marc Guardiani User-Agent: Mozilla/5.0 (Windows; U; Win95; en-US; rv:1.2.1) Gecko/20021130 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.arch.fpga Subject: Re: Unused Pins on big Virtex-II References: <5V_Wa.31676$Mc.2501134@newsread1.prod.itd.earthlink.net> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Lines: 42 NNTP-Posting-Host: 206.80.157.145 X-Trace: sv3-Il7Qgsd7jJxtOQw0uGHsQLz4du/4xT4+caB2ipFquGWtPtM0LKjgpF88rd7WRxJ9gyJU0r+IKtgbBc5!3sTQfrgYObKhfO0NvezkAFzBYTNF1OUwTs2/XHY6wJo4gWUagtClWMyIAUvTzpUoDw== X-Complaints-To: abuse@fyi.net X-DMCA-Complaints-To: abuse@fyi.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.1 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!switch.ch!news.mailgate.org!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!small1.nntp.aus1.giganews.com!border1.nntp.aus1.giganews.com!intern1.nntp.aus1.giganews.com!nntp.giganews.com!nntp.fyi.net!news.fyi.net.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:31471 I'd also advise bringing a bunch of them out to either a pad or a via that you have access to. Just in case you need to make a change and need more I/O :-). If you can bring them all out, then you (or the board house) can do boundary scan testing to ensure that all of the balls are connected. Andrew Paule wrote: > Don't assign 'em - should do fine - they'll float. > A solder pad is a good idea because these things come balled, and the > solder will just float around and find something to connect to (most > likely a nearby ball and give you a bridge - bit**) if you don't - talk > to your assembly house. > > Andrew > > William LenihanIii wrote: > >> We will be designing with a large (xc2v6000) Virtex-II part in a >> ball-grid >> array package that has maybe ~1000 balls, but we are using fairly few >> (~250) >> "mission logic" I/O. Add in power & ground, configuration, etc., we will >> have 100's of general-purpose I/O balls that are not needed. >> >> What should we do with them? Ground them? Let them float? If we can >> let them >> float, do we even need a solder pad on the PWB for them to "land on"? >> >> >> >> > -- Marc Guardiani To reply directly to me, use the address given below. The domain name is phonetic. fpgaee81-at-eff-why-eye-dot-net