Am 13.11.2010 um 12:15 schrieb Alexander Lehner: > > > Nikolaus, > > if you need a XRAY machine again, I could probably help you; I work for a > company which produces those XRay inspection machines. > > A.
That is great to know! Although I hope we don't need it again :---) Have a nice weekend, Nikolaus > > On Sat, 13 Nov 2010, Dr. H. Nikolaus Schaller wrote: > >> Hi all, >> time for another update. >> >> Am 06.11.2010 um 12:35 schrieb Sylvain Paré: >> >>> >>> Thanks for the news >>> >>>> >>>> Yesterday I received the second board where we >>>> did populate the TPS65950 (power controller). >>>> >>>> The results of measurements are: >>>> * the 32 kHz RTC clock is operating >>>> * when inserting a battery, most voltages are >>>> available as expected >>>> >>>> Bad news: >>>> >>>> * we have a short circuit on the 1V8 rail >>>> >>>> I have spent most of the night and this morning to >>>> track this down. It appears to be a solder short circuit >>>> under the TPS chip (a 0.4 mm pitch BGA). >>>> >>>> So I am currently sitting at our SMD rework company >>>> and looking over the shoulder of the CTO who has >>>> a lot of experience. Unfortunately I can't make >>>> photos. >>>> >>>> We already have unsoldered the TPS chip (that needs >>>> a really sophisticated machine) and the short has >>>> disappeared. >>>> >>>> The next step is to solder it back again and do the next tests. >>>> >>>> If that works, i.e. we get all voltages from the power controller, >>>> the 26 MHz oscillator should also start working. >>>> >>>> If that is ok, the OMAP and the POP memory will be soldered. >>>> Maybe we manage to get it today. Then, we can see if the CPU >>>> is doing something. >>> >>> Current status: the 1.8V is now working but the VDD2 (1.2 V) not. >>> The TPS chip aborts the power up sequence early. >> >> We could solve that by adding a jump start resistor. >> >>>> Rene will upload some photos of the board and we will >>>> post a link. >>> >>> Here: >>> http://download.goldelico.com/gta04/images/DSC00671.jpg >>> http://download.goldelico.com/gta04/images/DSC00672.jpg >> >> Then, we soldered the OMAP3530 and Pop Memory chip and >> connected RS232: >> >> http://download.goldelico.com/gta04/images/DSC00679.jpg >> >> It did identify itself as "40W" on the RS232 but did not boot beyond >> that. Fortunately the OMAP has a ROM bootloader (which generates >> the 40W sequence) and we could use it to download a special >> second stage boot-loader that has a simple commandline console >> on RS232. Note that it must fit into 64k SRAM built into the OMAP >> chip. So we are back to C64 times :) >> >> With this tool, we could identify that the (external) SDRAM has a >> stuck-at-1 error on a single bit-line. >> >> So we expected another soldering issue and had the OMAP+Pop >> replaced on Monday. But the error pattern remained the same! >> >> Unexpectedly, we were able to put the board into a 3D X-Ray machine >> on Tuesday (during Electronica Fair). Here are machine & results: >> >> http://www.yxlon.com/y.Cheetah >> http://download.goldelico.com/gta04/images/20111109%20Xray/ >> >> Fortunately it is *not* a soldering issue. And likely not a PCB production >> issue. >> >> Yesterday late at night we found the problem. It is a bad BGA ball assignment >> in our component library. VDDS_MEM (1.8V) is assigned to B17 instead of >> B18. And, B17 is data line 14 of the SDRAM and should have been left NC. >> Therefore we have tied one data line to a high-level... >> >> I think we can fix that for our samples but it needs some time and we >> run out of components for the samples. Especially memory chips have >> quite a long lead time. For the series version this will be very easy to fix. >> >> Nikolaus >> >> >> >> _______________________________________________ >> Openmoko community mailing list >> community@lists.openmoko.org >> http://lists.openmoko.org/mailman/listinfo/community > _______________________________________________ > Openmoko community mailing list > community@lists.openmoko.org > http://lists.openmoko.org/mailman/listinfo/community _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community