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Accurate Time Keeping in Embedded Systems

In many embedded systems, there is a need to keep accurate time/date. This is often performed using an RTC (Real-Time Clock). However,  uncalibrated RTC are not that accurate. For example, ST Microelectronics M41T94 RTC datasheet explains that: Uncalibrated clock accuracy will not exceed ±35 ppm (parts per million) oscillator frequency error at 25°C, which equates to about ±1.53 minutes per month. . In order to improve the accuracy, you’ll need to calibrate the crystal for each board at the factory using a frequency counter, that will greatly improve accuracy, for M41T94: When the Calibration circuit is properly employed, accuracy improves to better than ±2 ppm at 25°C. However, calibrating the crystal will further increase the manufacturing costs. Another way to have a very accurate time keeping, is to use the power supply frequency (50 Hz/60 Hz) which is extremely accurate due to interoperability requirements between electricity providers. In the diagram […]

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Finding a device IP Address

If you are developing software for an Ethernet (or Wifi) device, you’ll need to access the board for debugging and/or testing purpose. If your board does not have user interface or the serial port is not available, you’ll have to find the IP address (assuming it is using DHCP) before accessing the board thru telnet or ssh. A simple way to do that is to ping the broadcast address and check the arp table. > ping -b 192.168.0.255 WARNING: pinging broadcast address PING 192.168.0.255 (192.168.0.255) 56(84) bytes of data. 64 bytes from 192.168.0.246: icmp_seq=0 ttl=64 time=0.018 ms 64 bytes from 192.168.0.101: icmp_seq=0 ttl=64 time=0.217 ms (DUP!) 64 bytes from 192.168.0.246: icmp_seq=1 ttl=64 time=0.023 ms > arp -i eth0 arp -i eth1 Address                  HWtype  HWaddress           Flags Mask            Iface 192.168.0.103            ether   00:50:FC:00:00:01   C                     eth1 192.168.0.109            ether   00:13:20:01:01:01   C                     eth1 If you cannot find your device, it may be configured to […]

ArmSoM RK3588 AIModule7 NVIDIA Jetson Nano-compatible SOM
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Archos 70 Internet Tablet Video Review

Archos as just released a new 7″ Android Tablet. This device costs around 275 USD (249 Euros), which is a pretty good price for a device based on an ARM Cortex A8 at 1 GHz running Android 2.2, a capacitive touch screen (800×480), HDMI output (Up to 720p), built-in wifi (802.11n) and bluetooth 2.1 as well as a front facing camera. Bear in mind that you won’t be able to take pictures or videos with this device since there is no camera on the back of the device. Go to Archos website to get the full technical specs of Archos 70. Here are two videos of the device by Charbax. The first video shows web browser, video playback, google app market place, video playback on TV thru HDMI and facebook. The second video shows the dolphin web browser used with a bluetooth keyboard, video chat with fring (still have some […]

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Resources for Telechips TCC890x: TCC8900 & TCC8902

Telechips TCC 890x is now widely used in low cost Android Tablets among other applications (automotive, portable media player..). Here’s the description provided by Telechips: The TCC890x is a system LSI for digital multimedia applications based on ARM1176JZF-S, an ARM’s proprietary RISC CPU core. It is designed for high-end multimedia entertainment devices such as car AVN, portable multimedia player and home entertainment. The TCC890x supports decoding and encoding various types of video and audio standards with software and dedicated hardware codecs including JPEG / MPEG1 / MPEG2 / MPEG4 / H.264 / VC-1 up to Full HD (1080p) and MP3 / WMA / EAAC+ / AC3, etc. In addition, TCC890x offers a hardwired 3D graphic accelerator to enrich next generation GUI and other graphical applications. Although, Telechips claims to support WinCE, Embedded Linux and Android, they now fully focus on Android development giving other OSes a lower priority. However, the development board […]

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D-link Boxee Box available for pre-order

D-link Boxee set-top-box is available for  pre-order on amazon for 199 USD. It can only be pre-ordered to addresses in the US for now and shipments should start in November. D-Link disclosed that its device is based on an Intel Atom processor CE4100 (Sodaville), not an ARM or MIPS processor as many other STBs do. It is running on embedded Linux. Key features listed by D-Link for the device (beside its weird shape) are basically those of the Boxee media-streaming software on which it’s based: Enjoy thousands of shows available for free from your favorite networks, ready to watch at any time Check-out free movies from the web & watch new releases in stunning HD from premium movie services Play videos, songs, or pictures from your computer or home network Plays any non-DRM video, music, and photos and media from anywhere on the Internet The device features the following input/output and […]

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Android STB – WebTube HD

Here’s another Android Set-top-box that may come to the market soon. I do not have much information on this product, except it’s made by mnex – a Korean company. (Update: although the youtube video says otherwise, the design seems to belong to Innodigital (See Webtube HD details). The video below shows it supports Android web browser, Youtube, Google maps and interestingly an application market especially designed for TV (TV Application Market). Apparently, they control the box with a normal remote control, no track ball or touch pad, nor do they seem to have support for wireless mouse and/or keyboard. The demo looks good, although a bit sluggish. See for yourself:

Rockchip RK3568, RK3588 and Intel x86 SBCs and SoMs in 2025
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How to do a framebuffer screenshot

I’ll explain how to do framebuffer screenshots on 16-bit and 32-bit framebuffer. For 16-bit this is fully based on http://docs.blackfin.uclinux.org/doku.php?id=framebuffer Capturing screenshots Whatever the bit-depth of your framebuffer, the first step is to capture the frambuffer raw data on the board:

Now the you need to take the raw image, and convert it to a standard image format. This step depends on what type of display is there Converting 16-bit Framebuffer screenshot (RGB565) into png To convert the raw rgb data extracted from /dev/fb0, use iraw2png perl script

To do the conversion, type the following command in the host:

where 640 and 480 are respectively the width and height of your framebuffer. This has been tried on a 16-bit framebuffer on EM8620 series. Converting 32-bit Framebuffer screenshot (ARGB, RGBA, BGRA…) into png The solution proposed here is not as neat as the blackfin’s solution for 16-bit framebuffer, […]

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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 […]

Boardcon EM3562 Rockchip RK3562 SBC with 8 analog camera inputs