[GTA04] When is the next and more powerful openmoko releasing

[Dr. H. Nikolaus Schaller]

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
>> 
>> 
>> 
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