BeagleBone Black

For my recent electronics projects I wanted something more powerful than the usual Atmel megaAVR or AVR XMEGA microcontrollers I used in the past. The obvious step upwards in performance is some embedded system running Linux. A few years ago I played a little bit with an ALIX.3D3 embedded board, but nowadays most people would start with a Raspberry Pi and I also used to have an early model of those as well. Even though the Raspberry Pi seems to be everywhere there is a better alternative in my view: The BeagleBone Black. The most obvious advantage of the the Raspberry Pi (even compared to the Model B) is the much high flexibility concerning I/O. Most important it provides with its general-purpose memory controller (GPMC) a high-bandwidth parallel memory interface which is ideal for a fast interconnection e.g. with FPGAs.
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CHOST: i586 vs. i486 on AMD Geode LX

On my blog post about Installing Gentoo on ALIX.3D3 Mart Raudsepp made an interesting comment: He pointed out, that on AMD Geode CPUs it might be better to use i486 CHOST instead of my used i586, because the CPU is more like a i486 as far as instruction scheduling and times go.

This sounded interesting, so I googled for some benchmark test to measure differences. I found nbench, which measures performance by executing some typical algorithms and compares them to a Pentium 90 based system. So I installed it and run on the i586 CHOST system, then rebuild it completely to i486 CHOST and run it again. Continue reading


The AMD CS5536 Geode companion on the ALIX.3D3 board has several general purpose input/output pins. Most of them have different functions as well, and there are some registers to set if they should be used as special function GPIO pins. The ALIX.3D3 uses 4 GPIO pins for 3 LEDs and 1 mode switch. Accessing the leds is very easy using the leds-alix2 driver, but they can be addressed as GPIO as well. There is already a driver for the GPIO pins in the kernel named cs5535_gpio.c, but it uses a non standard interface to communicate with kernel. So, I wrote a new kernel driver using the GPIO interface. Continue reading

Updating BIOS on ALIX.3D3 within Linux

Usually BIOS updating means booting DOS and running a proprietary tool from the board vendor. A few days ago, coreboot's flashrom 0.9 has realeased. It's an open-source tool which supports program almost all flash chips used on x86 mainboards. Its compatibility list includes Geode™ CS5530/A, which can be found on the ALIX.3D3 board. So why not using flashrom to update ALIX.3D3 BIOS.

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