Linux Solutions

Embedded designer Paul Thomas is showcasing a tiny, open source computer at Linuxworld in San Francisco this week. “Linuxstamp” enthusiasts can obtain pre-built boards for $120 directly from the designer himself, or they can download the design and build it themselves for free.

Consisting of six integrated circuits; processor, flash, RAM, serial-to-USB, Ethernet PHY, and power converter, as well as a few passives.

Thomas demonstrated the capabilities of the Linuxstamp in the “Garage” area of Linuxworld. He showed a home-made robotic car, which was made with Lego, and moved around by wheels controlled by the stamp.

The Linuxstamp’s features include:

Atmel AT91RM9200 processor (ARM9 core, includes MMU)
32MB SDRAM
8MB SPI flash memory
10/100 Ethernet (supplied by the Atmel processor)
USB host port (supplied by the Atmel processor)
USB device port (generated by a serial/USB converter)
SD card slot
USB debug port (via the USB device port)
JTAG port
Can be powered via POE

Thomas tried to ensure the design remained simple so as to allow for a two-layer CB design, which reduces cost and encourages homebrew construction.

With the inclusion of a USB-based serial debug port, implemented via a serial/USB converter chip, users won’t need to use the boards JTAG debug port, according to Thomas.

Initialisation of the board’s low-level bootstrap loader is simple, Thomas said. The Atmel processor includes an innovative, built in hardware bootstrap function that automatically attempts to load the onboard SPI flash via the serial debug port when a newly built board powers up for the first time

The Linuxstamp runs Linux with two distributions currently available: a minimal filesystem that boots and runs entirely from within the Linuxstamp’s 8MB flash and 32MB RAM memory; and a debian-based filesystem that requires an SD card to supplement the board’s on-board flash.

In addition to the linux kernel, the minimal filesystem includes BusyBox and DropBear SSH among other basic system functions. The minimal system allocates about 2MB of the 8MB available flash to linux and the boot-loaders, with the rest for the filesystem, according to Thomas.