A13-OLinuXino Open Source Linux Computer Prototypes recap


OK, we build 5 prototypes and tested them for the last 5 days and this is the recap:

1. DDR3 memory is working correctly – check

2. NAND flash is working correctly – check

3. PMU is working correctly – check

4. A13 is running perfectly, overall the board consumption is about 1W in idle and 2W at intensive computing. The chip have large 6×6 mm metal heat dessimation pad which we connecto to large ground planes on the PCB.
What we measure is that running at 1 Ghz A13 increase it’s temperature just 2C above the ambient temperature.
This was immediately exploted by Dimitar Gamishev who reported that A13 could be overclock up to 1.5GHz 🙂
Generally with this heatsink eLQFP package is better for dissipating heat than A10 BGA package.
Of course this was done just out of couriousity we target industrial application and temperatures and overclocking is not recommended for normal operations. – check

5. Audio is working perfectly – check

6. Real Time Clock – works as expected – check

7. SD card works correctly – check

8. USB – works perfectly, there was minor issue with the GL850 hub, it have over current protection feedback with R58/R63 which in loop with the 4 capacitors was driving GL850 to oscilate the 5V power supply, generally this duplicate the SY6280 function, so we will remove it in the next revision.
We tested with Keyboards, Mouses, 3G modems and all they work correctly, Android have support for over 30+ 3G modems from different vendors build in, – check

9. Video – this is where we spent most of our time trying different configurations. As you know A13 have no VGA output, so we cheat it by creating simple resistor ladder Video DAC taking the LCD RGB, H-V sync pulses. We spent one whole day until we got the proper parameters set and we learned that A13 video controller pixel clock can’t go higher than 36Mhz.
This was confirmed by Allwinner later (this is part of the fun to work with processor without proper datasheet and user manual), so the maximum resolution we could squizee out of A13 LCD interface is 800×600 @75fps , well not perfect but – check

10. buttons: work fine, volume up down, home, back, power down/up and reset are all in good order – check

So overall we tested almost all features and they work fine, what remains untested: camera interface, GPIOs, SPI, I2C.

Known issues:

– A13 library component is not well done, I guess our developers used some of the standard Eagle QFP library with only 5.7 mils between the pads, this caused lot of shorts when the IC was soldered, we will increase the space between the pads to 8 mils for the next revision.

– Ground and Power planes stack-up was designed wrong in the first prototypes, we will switch them for the next revision.

So the conclusion: the first prototypes are success and work very good as for first attempt to route 1066Mhz DDR3 memory bus 🙂

17 Comments (+add yours?)

  1. motumboe
    Aug 03, 2012 @ 10:34:11

    This is a very good job! My compliments! Looking forward to get my hands on one of them! 🙂


  2. Cyk
    Aug 03, 2012 @ 15:05:34

    I didn’t follow the complete development process, but is it possible to get composite or RGB video output?


  3. Cyk
    Aug 03, 2012 @ 15:42:31

    Well, VGA is already an analog output. RGB Video just has another timing.
    Some older VGA cards could be configured to output VGA signals with a timing that would fit the needs of a color TV with RGB (SCART) inputs.
    I’ve done this many times to drive small video monitors with a PC VGA card.
    Is this also possible with the A13’s video controller?


  4. Cyk
    Aug 03, 2012 @ 15:59:08

    So would it then be possible to generate PAL and NTSC compatible RGB and sync signals?


  5. David
    Aug 04, 2012 @ 09:39:21

    So the video will be limited to 800×600 maximum resolution forever? If so, this is a serious problem AFAIK (a deal-killer for me actually). What is the color depth? 24-bit VGA color depth takes 48 resistors and 48 I/O pins (right?) – ouch! Is there any GPIO left (I have not found the schematic for this board yet).


    • OLIMEX Ltd
      Aug 04, 2012 @ 09:49:16

      the schematic is on GitHub the A13 LCD interface is with 18 bit and takes exacty 18 resistrs to implement
      I’m still amazed with so many links to GitHub from this blog and A13-OLinuxino web page at olimex.com how many comments related to the schematic or A13 features are posted without even bother to read the datasheet or the schematic 🙂


      • Vasi
        Aug 04, 2012 @ 17:12:53

        Don’t be upset, I think he really wanted to say “deal-killer”, “ouch!” and “not found schematic” …

      • David
        Aug 09, 2012 @ 06:37:04

        Wow, what an attitude!

        (1) You could have answered the VGA color depth in just a few seconds using just a few words. Instead you rail me for not wasting my time digging around on two different sites downloading .pdf’s then pouring through them sheet after sheet for an answer you had on the tip of your tongue.

        (2) You did not even bother to answer the 800×600 VGA resolution limit question. That specification is not on your A13-OlinuXino breif document, which I did download and examine.

        (3) I am watching the A13-OlinuXino carefully specifically because it is the only board of this ilk that has VGA out. No VGA out, or poorly performng VGA out is an absolute must for my application. So the words “deal-killer” are highly appropriate in my opinion.

      • OLIMEX Ltd
        Aug 09, 2012 @ 09:26:30

        sorry if you found my answer offending, Englih is not my native language so it may sound not good, but it’s not inentional I’m assuring you 🙂

        1. color depth is limited to A13 LCD interface which is 18 bit, A13 datasheet have listed all LCD signals, A13 have LCD interface with dedicated pins for this purpose so it doesn’t interference the number of the available GPIOs

        2. the resolution – of course we aimed to have 1024×768, but as written on this blog we work with poorly documented procesor and find all features the hard way 🙂 so we couldn’t know that max resolution of A13 is limited to 800×600 before we try it, I’m still not sure this is the maximum limit as then it make no sense inside A13 to have Video GPU with 1920x1080p but it’s not possible to get clear answer from Allwinner about this subject, so we will keep experimenting and see what happens

        3. sorry to hear that you application will not work on 800×600, the image we got is pretty decent and allow us to browse net, read e-mails, play games when you run android

        bottom line is that we still have to spend lot of more time to explore A13, this morning I got message that one of the developers who have from the first prototypes successfully ran OpenOCD JTAG with A13-OLinuXino and made some suggestions to break out the JTAG pins on separate connector for the next board revision, so A13 is still work in progress, very interesting and very exciting
        I feel like somebody who went and explore unknown territories, you never know what will come out at the end good or bad

  6. Cyk
    Aug 13, 2012 @ 18:42:39

    “we target industrial application”

    A cheap chinese consumer chip in an industrial application?
    Good luck with that.


    • OLIMEX Ltd
      Aug 13, 2012 @ 18:56:53

      A13 have -25+85C operating temperature and running at 1GHz it’s temperature rises just 2C above ambient temperature on our prototypes 😉

      Indeed A13 is cheap as Allwinner sells more chips in China than other competitors worldwide.

      Everyone knows that all Cortex-A8 SoC US, Chinese etc are made in one and same factory – Taiwan Semiconductor Inc. and use same IP from ARM, so you get about same quality no matter from where you buy it.


  7. Cyk
    Aug 15, 2012 @ 15:56:25

    So all other suppliers of ARM chips for industrial, automotive, avionics, etc. should go home and leave the business to Taiwan Semi?
    Interesting opinion.
    You don’t even get a real datasheet for that thing. And don’t even think about a safety manual.


  8. minh
    Aug 17, 2012 @ 11:43:13

    Hi, i want ask for setup stack layer pcb, you used in your pcb? do you used imperdance controll in your pcb? i has successfull develop my beaglebone with ddram2 by lowcost pcb
    (no imperdance controll) i hope develop one pcb of coretex a13 with lowcost pcb? can i do it?


    • OLIMEX Ltd
      Aug 18, 2012 @ 08:23:32

      the layer stackup is in Eagle CAD files on Github, we used impedance control for the DDR3 lines, beaglebone DDR2 runs at 266 Mhz, you can give it try for A13 with 533Mhz DDR3


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