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uClinux kernel panic: Stack overflow

If you’re using ucLinux, you may get kernel panic errors coming out of nowhere. There may be several reasons (buffer overflow, out of memory..), but the most common is stack overflow for the process or one of the threads. To increase the stack size of a flat binary you’ll need to adjust the LDFLAGS as follows:

This will set the stack size to 64KB. To change the stack size of a thread (e.g. 32KB below), you’ll need to set the stack size attribute:

How to detect which thread suffers from stack overflow? First, you can check your code for recursive function calls and local variables (especially arrays) both of which will be added at runtime to the stack to estimate what should be the stack size. So if you have large arrays you may use a pointer + a call to malloc instead. If this can not fix […]

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Digital Signage Standard by POPAI

Currently digital signage implementations are mainly proprietary, and that means once you choose a vendor you are stuck with it, unless you completely change your network and the way you manage your content or handles separate systems. If the digital signage industry really wants to take off some standards are needed. One of the first standard for digital signage has been released by POPAI (Point of Purchase Advertising International). This first standard is to promote interoperability between different providers by defining Screen Media Formats (Click to open the standard) basically telling which video and audio codecs and containers (“Wrappers”)  and which and picture formats  should/could be supported by digital signage players and providing different levels of standard profiles and extended profiles a bit like it is done in MPEG-4 specifications. POPAI also used to provide some media samples to test your system previously available at www.popai.com/DS/ContentSamples but the link is […]

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Installing 2 Linux distributions in one PC

Here are the step I followed to install two distributions of Linux: Install the first distribution normally with GRUB in the MBR. While installing the second distribution make sure to set GRUB in its root partition. At this point the second distribution should not be available in GRUB Boot loader, login in the first distribution as root and edit /etc/grub.conf and add the following lines: Linux Distribution 2 root (hd0,2) chainloader +1 Save and restart your PC you should have 2 choices in GRUB, select “Linux Distribution 2”or whatever name you gave in grub.conf and this should start the second Linux distribution.

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EP9307 Thin Client with DirectVNC

One of my reader had issues running Thin-clients ENTC Encore-1000 based on EP9307 and wanted to update the firmware in his systems. So I’ll explain how to access Linux, Windows XP or any other operating systems using a thin client based on Cirrus Logic EP9307 hardware. This is for reference only, and the performance may not be suitable for your environment/setup. One PC (server) is needed to run VNC (Virtual Network Computing) server for each remote desktop (i.e. each thin client), then the thin client can run the software without hard disk by just using the network connection. This can be used for checking emails, browsing internet, office applications, etc.. All resource heavy tasks are done on the server side whose specifications may be chosen to match the applications requirements. I’ll explain how to use Linux, but Windows XP (or any other operating systems for that matter) could also be […]

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IPAD Killer – Allgo Android Tablet

Ok, the title is a bit over the top but the Allgo tablet reference design running android would only cost around 35 USD to manufacture (15 dollars for the board, 15 dollars for the touch screen display and 5 dollars for the battery). So you’d be able to browse the web, read e-books, flicker through your pictures and access a wide range of applications through Google app store for less than 100 USD (retail) compared to  the IPAD retail price of 499 USD that would seem like a bargain even though the performance is not as good as the IPAD (but still acceptable) as you can see in the video below.

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ARM-based Android Set-Top-Box

Last month, I posted a blog entry about demo featuring Sigma Designs Android STB that was shown at CeBit last January. AFAIK this is still being developed and there is still no Android STB products based on Sigma Designs Chips that can be purchased. Earlier this month, another company Webia Technologies demo’ed an Android STB (HDMI 1080p – ARM 11) whose factory price would be 50 USD, which is well below the price of a similar Sigma Designs STB based on SMP8640 or SMP8650 series. They also showed a smaller box that can support 720p and selling for 25 USD (Factory price, not retail price). You can see the demo below showing both set-top-boxes. Interestingly enough, I was unable to find Webia Technologies website or other previous news about this company. All I found is Webia Technologies is supposedly registered in Hong Kong. Update: After searching which ARM-based solution may […]

Rockchip RK3568/RK3588 and Intel x86 SBCs
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Digital Signage Features – A Quick Guide to Select Your Digital Signage Solution

There are a lot of different digital signage solutions around and it may be difficult to find which one is right for you since there can be quite a few different features and options. So I’ll do my best to explain the main features to guide your choice if you are planning to purchase a digital signage solution (embedded signage player, content management software and server). I’ll focus this post on the digital signage player, but bear in mind the content manager software is equally very important. [ad#Google Adsense – Wide Banner] Hardware features Video outputs: composite, component (YPbPr), VGA, DVI, HDMI, LVDS The capability to output simultaneously to different video outputs maybe an advantage if your plan is to use one player to output to several monitors. Video resolution: Standard Definition (e.g. NTSC) vs. High Definition (e.g. 1080p) This is a simple choice based on costs and whether you […]

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Embedded Software Quality Assurance (QA)

[ad#Google Adsense – Wide Banner] As for every software there needs to be quality assurance testing for embedded software with a special focus on reliability since this is often key in embedded systems. Software testing / QA may be a very controversial subject as everybody may have very diverging and strong opinions on how it should be done, and the way it is done also depends on the company culture (and size). So here’s the way I personally see the different steps to testing, please let me know if you feel otherwise in comments. Unit Testing: This is the lowest type of test (white box testing) where the developer should check the implemented functions work as expected Functional Testing: Although the software team should check if the main functionalities of the software work properly before committing the code (assuming you are using a version control system and you should), QA […]

Boardcon Rockchip and Allwinner SoM and SBC products