Well, you learned about the PCBs and displays in the last post, time to
update you on the rest.
Let's start with...
The case
--------
I received an update a while ago which has been adapted to the display
and all our other components (PCB, the battery, etc.) It's nigh
finished and the shoulder buttons received a new design as well (yep -
they do look familiar. The idea for those came from the community -
thanks for that!) If you want to see pictures, check the blogpost
linked at the bottom of the mail.
However, to fit the display, they increased the width of the device by
1,4cm... something we don't want (right? :)) They tried to keep the
screws in the lid, but I rather want them removed and have some other
way to fix the lid (i.e. with clips - but better ones we had on the
Pandora) and keep one screw in the middle area.
This is now being worked on. It will change the shoulder buttons a bit
as well, but hopefully, not too much. I'll update you once I got the
next design - which will then also be printed for a test with the
prototype PCBs.
Nothing moved ahead with the keymat, as they need the final case design
first. However, the keymat is simple, and the first sample (with
correctly sized keys) took two weeks, so I guess once they get the
final design, it'll take about the same time.
The battery
-----------
As you might remember, the 6000mAh battery is a bit wider than Pandoras
battery, so the battery compartment had to be changed to fit that. This
change has now been added to the case, so we knew exactly where to
place the contacts of the battery. And because of that, we could now
order the battery. We will receive 20 samples about end of February
(hopefully ;)) and when we confirm them to be working fine and fitting
well, 3000 batteries will be produced and shipped about end of April
(so we'll get them in June / July).
The LCD Cable
-------------
The last missing component is the LCD cable - and prototypes are being
produced now as well. I don't know yet when we'll receive them, but
hopefully it'll be end of February as well. They're a lot more simple
as the Pandora cables, as they have less traces, only use one side (not
two), have less edges (and all of them are rounded) and no electrical
components on them. All traces are redundant as well, so if one trace
breaks, the cable still works fine. Two traces of the same signal would
have to break to make the cable go bad - and that should not be that
likely.
So... did I miss something?
I don't think so, but if you think I did, let me know and I'll reply to
you :)
We should now also start to think about the packaging (what items we'll
include, what package design we'll choose), etc. I'll probably start a
poll about the items as well.
Discuss about that post and view the shoulder button pictures on the
webboards:
http://boards.openpandora.org/topic/17717-of-cases-and-batteries/
Follow me on twitter for short news inbetween:
https://twitter.com/EvilDragon1717
Sorry for the loooooong time without an official blog update - it's not
the case that so little happened that there was nothing to post... the
problem was, that I had so much work to do because so many things moved
forward, that I didn't find the time to actually post an update.
Additionally, end of the year always means you need to do your bookings
and stocktaking... so that needed quite a bit of time as well.
Well, as so many things have happened, I'll spread those over multiple
blog posts once again.
Let's start with...
1. The PCBs
-----------
As mentioned last time, the layout for the main PCB has been finished
and the PCBs and all parts except for one coil are already here with
us. Yep, it's a simple coil that's out of stock right now, but it's
ordered and will arrive early February, which means it's prototype time!
Nikolaus is working on the CPU PCB right now and about half-way
through, which means he should be finished roughly middle to late
February. The ordered OMAP5 are already on the way to us, so it looks
like CPU PCBs we'll see a prototype release in February as well (except
one other part will get a delay, which is something you never know when
doing prototypes).
Well - these PCBs will most probably be the last revisions before the
mass production (unless there are some serious errors), so we're moving
forward here.
2. The display and the rotator
------------------------------
Thanks to the awesome help of the BOE team, we were able to include the
correct initialization sequence in our driver and the display is now
working perfectly. We need a bit more work to use the rotator chip
though. It should be easy - but once again we are able to proof that
Murphys Law is always true!
Now things get a bit technical - if you don't want to know exactly
what's going on, skip the next section.
--------------- START OF TECHNICAL DETAILS ---------------
So, let me explain how it should work in theory:
The routing of the Video signal is:
OMAP5 -> Rotator Chip -> Display
The signal is being sent via MIPI. MIPI is a digital standard that
allows to send commands (like enable / disable rotation, change
backlight, change powersaving settings, etc.) as well as a video signal.
The first thing to do to make a display work at all is to send an
initialization command, so that it switches on, configures itself and
accepts the MIPI Video signal. This is what I mentioned above which is
already working fine.
Then we got the rotator chip inbetween. We need to be able to send
commands both to the rotator chip and the the display. To be able to do
that, Solomon (the manufacturer of the chip) implemented an easy way to
do that: There's a bypass mode, so that all commands will be directly
sent to the display.
To to initialize our display, we need to switch the rotator chip to
bypass mode, send the initialization sequence, disable bypass mode and
enable the rotation.
The bypass mode can be enabled or disabled with a command sequence. The
sequence starts with 0xFF. This would in theory work perfectly fine -
but the initialization of the display ALSO starts with 0xFF. Solomon
also thought of that. In order to send a MIPI command sequence that
starts with 0xFF, you simply send 0xFF twice.
So far no problem. However: MIPI command sequences have a maximum
length of four bytes. And the initialization command sequence of our
display uses the full four bytes. Now THAT'S a problem: As we need to
send 0xFF twice to tell the Solomon chip to pass through, we can only
send a sequence of three bytes.
So... Murphys Law has fully struck us. By chance we got the worst
combination possible: If the initialization command sequence of the
display wouldn't start with 0xFF (or the Solomon chip would use a
different byte for the bypass command), it would work without issues.
And even then - if the sequence would only be 2 or 3 bytes long, it
would STILL work. A start with 0xFF and 4 bytes long however is the
ONLY combination that doesn't work!
So, yay for this! I should really start playing the lottery!
But don't be afraid - there's a solution for this.. it just means a bit
of more work for us: We can flash the display driver IC so that it
initializes the panel automatically as soon as it is connected.
------------------- END OF TECHNICAL DETAILS --------------------
In order to use the Solomon chip, we need to flash the driver IC of the
LCD. This is no problem in mass production, as BOE will do it for us -
however, for our prototype panels, we need to do that ourselves. It's
not that complicated, but we need to modify one of our display PCBs for
that.
We decided to do that AFTER the CPU PCB is finished, so we can't test
the rotation chip before end of February (probably).
Both BOE and Solomon are giving us GREAT support here, that's awesome :)
3. The touchscreen
------------------
Upon testing, we found that the first touchscreen we received for our
displays was not responsive enough. It's similar to a batch of Pandora
touchscreens we had: It works fine with the stylus, but doesn't really
react to your fingers (unless you press really hard).
It took about only two weeks to get new samples of a different
touchscreen - and it works a lot better. Nikolaus tested it and
according to him, it works a LOT better (and reacts to your finger
gestures as well). I'll pay him a visit this week to check it out
myself and make sure it works fine.
So, today's newspost gave you the current information about the PCBs,
the display including the rotator chip and the touchscreen.
Coming soon: The case, the battery and the LCD Cable.
Feel free to ask any questions here, as usual :)
Discuss about that post on the webboards:
http://boards.openpandora.org/topic/17697-of-boards-and-displays/
Follow me on twitter for short news inbetween:
https://twitter.com/EvilDragon1717
