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Messages - IPenguin

2
Open Bench Logic Sniffer / Re: spartan/virtex 6 + ddr2/3 ?
[quote author="tayken"]Hi arhi, just today I found this through Hack a Day. It reminded me of your trial of BGA soldering with vias. I guess the problem was using vias maybe?[/quote]
tayken, great find! So it doesn't (directly?) explain what arhi experienced during his trials.
I have asked a friend to get me a batch of (similar "failed" silicon in) BGAs with a working
JTAG chain (access to all pins) ... I think there is a demand for BGA soldering capability for
hobbyists to assemble prototypes/test boards with rather simple tools ... however, production
will remain the domain of PCB assembly/testing services.

@arhi, even if you didn't experience capillary effects directly you may have run into a combination
of gravity and surface tension that still sucked/pulled the tin away from the pin(s) ...
3
Open Bench Logic Sniffer / Re: spartan/virtex 6 + ddr2/3 ?
For comparison I did a quick check on SO-DIMM size (68mm x 32mm) 6 and 8-layer chem gold finish boards with two local (German) companies I know and consider rather expensive.

6-layer - cost for 100 pcbs
A - 651 EUR --> 6,51 EUR/pcb
B - 484 EUR --> 4,84 EUR/pcb

8-layer (incl. 1 progr. blind vias) - cost for 100 pcbs
A - 965 EUR --> 9,65 EUR/pcb
B - 778 EUR --> 7,78 EUR/pcb

More than doubling the size (to OBLS size ca. 90mm x 50mm) will raise the price by roughly 50%.

Prices excl. VAT and shipping ... no hidden cost!

Does this mean: Expensive German 8-layer board is still cheaper than cheap Chinese 4-layer board?
5
Open Bench Logic Sniffer / Re: spartan/virtex 6 + ddr2/3 ?
@arhi: Thanks for sharing your BGA soldering experiments/experience. Sorry to hear that you did not have any success despite all your efforts. I agree with your conclusions:

1. Yes, surface tension will fix slight misplacements. :)

2. Since surface tension corrects misalignment (torsion/yaw) to a lesser degree than misplacement
    a simple but via optical guidance precise PnP could reduce assembly time and help to reduce "duds".

3. For various reasons there is no other (affortable) way but to use a reflow oven and solder with the specified ramp up profile.    (actually the vias in the (center?) of the pads may have caused the issues ... because they may have disrupted the surface tension ... I am not sure if I understand your the configuration of the pad/via configuration correctly, so).

4. If you go BGA you have to go 6 layers unless it's a real small/simple package, e.g. only one or two pin rows.

Anyway, assembling BGA designs is a more general subject. Not sure if there is much interest for it among members of the DP community.

Since O(B)LS started out with a SUMP implementation on GFs Butterfly board (predecessor of Papilio) the next generation Papilio with Spartan 6 should make for a good platform for those who may need more performance/features than the OBLS can offer.
6
Open Bench Logic Sniffer / Re: spartan/virtex 6 + ddr2/3 ?
Maybe it's time for a simple high-precision Mini-PnP project bare auto-feeding.
One that can place single BGA packages, narrow pitch QFPs ... essentially every
SMD component step by step even if it requires swapping the grabs/stamps
(tools) by hand ... for prototype and small batch assembly. We need to keep up
with advancing packaging and assembly technologies :)

... I know, at some point 2-layer PCBs won't do anymore :(
7
Open Bench Logic Sniffer / Re: spartan/virtex 6 + ddr2/3 ?
[quote author="arhi"]That's why I asked if DP is designing a new board :D. If I could find a good chip in 208 tqfp I'd try to do it myself (not sure 208 is enough for ddr2 also, they are 72pin modules iirc)[/quote]
Just a teaser:

Check out Spartan-3 and Spartan-3E in 208 pin PQFP package:
- XA3S200 (PQG208) - max. 141 user I/O
- XA3S400 (PQG208) - max. 141 user I/O
- XA3S250E (PQG208) - max. 158 user I/O
- XA3S500E (PQG208) - max. 158 user I/O

No real performance gain with those Spartan-3/3E devices compared to the OBLS ver. 1, so!
... and sourcing the devices in the 208-pin QFP package may turn into a real head banger ;)

I wouldn't discard Zynq-7000 EPP right from the start ... the dual-core Cortex-M9
on the chip may have some real value ... --> Free webinar: FPGA programming in C code

Off topic ... not really (since I read some comments on the blog entry for the webinar
- not the ones about webinars in general as I am no fan of live webinars myself):
Some people were laughing when Miro Samek published his book Practical State Charts in C/C++!
I loved the idea right from the moment I read the headline since I had been using C to
convert state charts/diagrams and generate fusemaps for ROMs and PALs (the first
commonly available PLDs to implement state machines) long before the book had
been published! However, it took me to read the title of the book to understand
that state machines are perfect to implement solid, determined and very efficient
code for MCUs. Since then I have used this approach for bare metal coding many times.

Getting back on subject, there are some real benefits in splitting tasks between MCUs
and logic/gates both residing on the same chip in particular if there is a need to change
between different functions/state machines that would take up more logic footprint or
paths than the FPGA can provide but are not very time critical ... the combination of MCU
and logic array allows the design of "dynamic" logic (vs reloading the FPGAs configuration)
... a feature that comes in rather handy e.g. for reactive pattern and waveform generators etc.

Regardless, Zynq-7000 are no good choice if the design requirements exclude any
components that can not be assembled by hand (BGAs etc).
8
Project development, ideas, and suggestions / Re: Alternative to Raspberry Pi?
[quote author="Squonk"]BTW, the Olimex iMX233-OLINUXINO-MICRO linux sold on eBay raised from 19.95 GBP to 27.95 GBP (+40%) over the last few days...

It is now aligned with the price on Olimex website (more or less, depending on shipping destination).[/quote]
Hmmm, now I see where this thread's title is coming from - you got inspired by the product description on ebay.

Actually the current ebay price is 24% above Olimex regular list price for single qty (EUR 28,74) now
(don't forget to add 20% VAT to prices shown on the Olimex pricelist if the shipping address is within
the EU and you have no EU VAT-ID)!

(EUR 23,95 * 1,2 --> EUR 28,74 = 22,56 GBP <--> GBP 27,95 = EUR 35,60 - exchange rate: 0,785 EUR/GBP)

But then the UK is a funny place to order electronic/computer stuff/equipment from  anyway ...
prices tend to be 20% and up higher than in other parts of Europe/US ... at least for those living
in/buying from eastern/central Europe :P
10
General discussion / Re: current draw from small USB WiFi adapters
Thanks a lot for sharing this rather useful info on some common USB 2.0 WiFi adapters. :)

[quote author="jbeale"]---
http://www.ebay.com/itm/330646461862
Ralink RTL8188CU USB-WiFi N adapter  (internal antenna)
standby: 84 mA
DSL provider speed test, transmitting: 96 mA (max)  11 Mbps
DSL provider speed test, receiving: 94 mA (max) 0.91 Mbps
iperf speed test to local WinXP box: 157 mA (max) 18.7 Mbps
---[/quote]

Minor correction to prevent confusion:
RTL8188CUS (1T1R), RTL8188SU (1T1R), RTL8191SU (1T2R), RTL8192CU and RTL8192SU (2T2R)
are Realtek (not Ralink) single-chip IEEE 802.11b/g/n USB controllers.

My favorite RTL8188SU based USB WiFi adapter is the LogiLink WL0085 - it has a detachable
antenna (RP-SMA connector) and comes at < 10 EUR. So far it has worked flawlessly on all Linux
boxes/boardes I have used it with (various DVB-S/T Linux boxes, iMX233-OLinuXino, CS-E9302,
NSLU2, GNUBLIN ...). and on Windows PCs. I have measured up to 175mA drawn by RTL8188SU
based adapters @ ~20Mbps (TX).
12
Project development, ideas, and suggestions / Re: Alternative to Raspberry Pi?
[quote author="Squonk"][quote author="IPenguin"]The MK802 has been around for a few month.[/quote]
From the video linked above featuring the developer, the first prototypes were finished in May! Preorders started June 7th. So I grant you one month, not a few ;)[/quote]
You are right, first units became available for developers in June ... and it's a nice hackable device :)
A very affortable platform to gain experience with the A10 (and A13) SoCs.

... and here's the first hardware hack I have seen for the MK802: MK802 UART port (out only?) :)

Who will be the first one to hook up his BusPirate (or any other UART adapter) and post a pic/screenshot?

Anyway, I don't consider the MK802 or any of the other A10 based thumb sticks or APCs as an alternative
to Raspberry Pi, at least not for the audience the Raspberry Pi is intended for ... but that's an other story.
13
Project development, ideas, and suggestions / Re: Alternative to Raspberry Pi?
At IN4DEALZ.com tke MK802 sells for US$ 59.99 including international shipping
- the deal is on for an other 2d 15h!
However, you may want to look for the MK802 version with 1GB RAM ;)
... and the MK802 has NO Ethernet and NO (accessible) GPIOs

The MK802 has been around for a few month. Even Linux ports are available by now.
However, the video performance (multimedia & 3D) under Linux is not as good as under Android:
- New Ubuntu image for the MK802 is pretty usable
- Linux central for MK802
14
General discussion / Re: Allwinner.....
I am not affiliated with Olimex (but I admit to have met some Olimex team members
before and to use some of their boards ;).

Anyway: Here is the "official" list of Olimex distributors/resellers - further down the page.

P.S. Shortly I will start a thread for a discussion about the open source issues regarding ARM
based SoCs with 3D GPUs. The problem of closed (not open) GPU documentation is NOT the
board designers/manufacturers fault! Hence may I suggest to keep the discussion seperated
from boards, tablets, devices being designed/built around such SoCs.

@andersm: I agree that it's a big annoyance to see the market being flooded with Android
(and Linux) devices, most missing the GPL notification and the link/address for downloading
/ordering the GPL source. Good subject for an other discussion :D
15
General discussion / Re: Allwinner.....
The tablet ginpb points us at is one of the dozens if not hundreds of tablet designs based on the Allwinner A13 SoC - it comes in a 174 eLQFP package - the same chip the A13-OLinuXino board is being designed around. It's the A10 that comes in a BGA441 package.

Btw. here is the schematic of the A13 tablet reference design - most A13 based tablets cook down to the Allwinner A13 reference design. Beware, there is at least one trap/bug in this reference schematic!

Here is an other A13 tablet the ICOO D50 II Dulexe 7 inch Android 4.0 Tablet PC AllWinner A13 512MB RAM 4GB Build in WIFI that sells for US$ 69.99 (includes free shipping from Shenzen). Actually A13 tablets (w/o HDMI, Bluetooth, GPS, 3G) sell for US$ 40-45 in quantities for the 1GB RAM version ;)

... and one with 1080p (mini/micro HDMI?) out, 1GB RAM and 8GB NAND Flash - ONDA Vi10F ...

And here are some details on how the Allwinner A13 became the dominant SoC in the low-end Android tablet market lately - the (in)famous A13 success story.

More info on the A13 can be found in the "Alternative to Raspberry Pi?" thread.