[Gta04-owner] GTA04A5: you will hate and you will love this mail

H. Nikolaus Schaller hns at goldelico.com
Thu Feb 11 17:37:20 CET 2016

Hi Neil, hi Thierry,

Am 11.02.2016 um 17:02 schrieb Neil Jerram <neil at ossau.homelinux.net>:

> FYI this is a bit 'tl;dr' for me.  Actually I did read it quite well, but
> still struggled to see the overall message

ok, sorry for that. It always happens if you collect a lot of information but
don't have enough time to write a well-designed posting.

> - GTA04A5 is still alive but will
> take longer than planned?

Yes. A longer that planned and last time announced, but not much.

In fact to answer the question of Thierry, there is a good chance that the final
order for production can be done as early as by end of next week. There isn't
much to be done (some paperwork, checking/improving the PCB layout for
another time, testing the 1GB RAM chip).

How long it takes to get the remaining components is guesswork but
~4 weeks until the first PCBs can be built is a good guess.

There are only two open questions:
* RAM verification which needs us to succeed in replacing a RAM chip in an old GTA04
* WL1835 or WL1837? The latter being ~20 EUR more expensive but having 2.4GHZ / 5.8 GHz

What are your opinions on the WL1835/37?


> So, please consider adding a summary.
> -----Original Message-----
> From: gta04-owner-bounces at goldelico.com
> [mailto:gta04-owner-bounces at goldelico.com] On Behalf Of H. Nikolaus Schaller
> Sent: 10 February 2016 19:28
> To: List for communicating with real GTA04 owners
> <gta04-owner at goldelico.com>
> Subject: [Gta04-owner] GTA04A5: you will hate and you will love this mail
> Hi all,
> you might wonder what the status of the GTA04A5 is.
> Unfortunately there has not been much progress since I had to spend much
> more time on making the Pyra (OMAP5) hardware working and verifying that it
> is indeed mass production ready than anticipated. This was really exhausting
> because it was squeezing a phase that would normally need several months
> into just some weeks.
> There had been a lot of details to be fixed. Not much if you see the result,
> but each issue needed 110% attention for several days until a reliable fix
> was found (and some are still open). For example, there were boot problems,
> where the Linux did sometimes start to boot, but suddenly stopped. Sometimes
> it reported CRC errors.
> This turned out to be a 15pF capacitor to attenuate the MMC clock signal
> since it may disturb the GPS receiver (63th harmonic of the
> 25 MHz clock). A lesson we learned twice for the GTA02 and GTA04.
> But this time the 15pF was good for GPS but too much for the MMC.
> It made the MMC interface of the OMAP5 to fail spuriously. Such bugs make
> grey hair and need a lot of time - and can't be parallelised by having more
> people to work on it.
> But now, we are almost through and the OMAP5 is starting to work reliably.
> This has a nice side-effect, which is very important for the GTA04A5 project
> and the reason why I report it today.
> The GTA04A5 needs some replacement components because the old ones used in
> the GTA04A3 and A4 are no longer available. Even for money.
> One of them is the WLAN/BT combo W2CBW003.
> So the plan is to replace it by a modern WL1835 module [1] which adds more
> WLAN frequencies, speed and adds Bluetooth BLE 4.0.
> But it would be risky to throw it into the schematics, make a PCB layout and
> build the ~100 GTA04A5 we have on plan. The risk is that it does not work
> and we have no chance and money to fix.
> Fortunately, the Pyra also has such a module :) And yesterday, I was able to
> get it alive for WLAN and today for Bluetooth. This means that the way it is
> wired up to the OMAP5 MMC4 interface and UART2 is working!
> And, the way the setup is done in the Device Tree also works.
> Since the OMAP3 is not different for these interfaces, I am now sure that we
> will not make a mistake if we throw in the WL1835 into the GTA04A5. This is
> the good thing! It simply will work with the 4.5-rc3 kernel (and slightly
> different commands in user space).
> The other decision blocking the GTA04A5 production is the 1GB RAM/NAND chip.
> Before deciding to solder them all on the ~100 GTA04A5 boards, I would
> like to test it a little with some old (partially broken) GTA04 board. This
> means desoldering the original 512 MB PoP (Package on Package) RAM/NAND
> chip. But without damaging the DM3730 CPU. And then solder the different PoP
> chip on top [2].
> Desoldering is easy (since we now have a new vapour phase machine with BGA
> desoldering tools). But soldering a new chip, especially Package on Package
> is really tricky. First experiments did make the new chip swim away so that
> it was soldered in a wrong position :(
> Therefore we have aborted that to find a solution. There are ideas, but this
> needs more experimentation time (i.e. days) until it becomes successful.
> Unfortunately another topic queued up behind making the Pyra handheld
> production ready.
> So I have to apologize that we can't keep the availability date, but it is
> really not much missing. Except time to do what is needed.
> I am really sorry for that delay which might come a little unexpected since
> I did not even give some status updates in the last weeks.
> This is something I promise to change again.
> There is also something on the horizon: a Kernel and QtMoko hacking weekend.
> The plan is to meet in some cosy place and have some core hackers just work
> in two teams to fix remaining kernel issues on one side and overhaul QtMoko
> to run on top of stock Debian Jessie. Replicant will also be represented,
> and we hope that we can then even use our Letux standard kernel for
> Replicant.
> Please let me know if you want to participate/contribute.
> And of course if you have questions about the GTA04A5.
> A final note: we have a new mailing list for Letux kernel development [3] so
> that this list does no longer need to be cluttered by tiny details and patch
> discussions.
> Sorry again for the delay and thanks for your patience.
> -- Nikolaus
> [1]: http://www.ti.com/product/WL1835MOD
> [2]: https://en.wikipedia.org/wiki/Package_on_package
> just a note: we have the "or less" variant in the picture: 0.5mm on top and
> 0.4mm on bottom
> [3]: http://lists.openphoenux.org/mailman/listinfo.cgi/letux-kernel
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