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Tiny hacker SBC offers robot-friendly Linux distro

Jan 20, 2014 — by Eric Brown 4,214 views

[Updated Jan 21] — The Kickstarter-backed “Rex” is a $99 robotics SBC with a DSP-enabled Cortex-A8 SoC, camera and audio I/O, dual I2C ports, and an Arduino-friendly “Alphalem OS” Linux distro.

A recent Georgia Tech study found that Kickstarter projects often find success thanks to the use of effective marketing buzzwords like “guaranteed.” That word never shows up the Rex project’s Kickstarter page, which is perhaps one reason why this promising project has yet to reach a third of its $90,000 funding goal, with less than two weeks to go. We think Rex is worth a closer look. (Satisfaction guaranteed!)

Another reason Rex has yet to find momentum is that others, such as the similarly Kickstarter launched Udoo board have also tried to wed a Linux single-board computer (SBC) with Arduino-like microcontroller functionality. Intel is collaborating with Arduino on its Linux- and Quark-based Galileo board, which also features Arduino compatibility.

Alphalem’s Rex single board computer
(click images to enlarge)

There are some key differences, though. For example, while Udoo and Galileo are both general purpose hacker SBCs, the Rex, should it ever reach market, is targeted primarily at robot makers. Also, rather than embedding a specific Arduino-like microcontroller subsystem, it instead depends on a built-in DSP, as well as dual I2C ports that support a wide variety of microcontrollers, as well as microcontroller-based Arduino boards.

Rex supports numerous robotics peripherals
(click image to enlarge)

Developed by Carnegie Mellon robotics grad students Mike Lewis and Kartik Tiwarti, Rex even comes with its own homegrown, robotics-focused Linux distribution called Alphalem OS. The Arduino-friendly Alphalem OS enables robot designers to program a robot onboard without uploading code to a microcontroller (see farther below).


The Rex is targeting hardware hackers who have tried to build robots based on the Arduino or Raspberry Pi platforms, or perhaps attempted the more challenging task of hacking together a robot that uses both. In a Jan. 13 TechCrunch interview, Lewis was quoted as saying: “It’s a higher price than the RPi, but the experience of building a robot is less of a pain — no hassles for wiring, it has built-in battery inputs, and it boots up directly into a robot programming environment.”

The board runs the supplied Alphalem OS or another Linux distro on a Texas Instruments DM3730, a 1GHz Cortex-A8 system-on-chip that is perhaps best known in the DIY community for running on the BeagleBoard-xM, the SBC used by the developers for prototyping. The DM3730 also drives the open source Neo900 smartphone. The SoC provides a 3D graphics accelerator, but more importantly for the Rex, it also includes an 800MHz C64x+ DSP (digital signal processor) core.

The tiny Rex board also provides 512MB of RAM, as well as a microSD slot for storage, and features a USB host port, a camera port, and audio I/O jacks. Other than that, you get dual I2C ports for device control, as well as a 14-pin GPIO header and a kill-switch header.

The I2C ports support both 3.3V and 5V unregulated power output. Rex also provides 6-12V battery inputs for mobile use and 5V input for desktop use. The board supports up to 20 Amps, as long as the current is distributed equally on both sides of the board, say the developers. No dimensions were supplied, but the Rex appears to be just a few inches on each side.

Rex specs

Specifications listed for the Rex SBC include:

  • Processor — TI DM3730 (1x Cortex-A8 @ 1GHz); 800MHz DSP core; 3D accelerator
  • Memory — 512MB LPDDR RAM; microSD slot
  • I/O:
    • USB host port
    • Camera module port
    • 3.5mm stereo audio-in
    • 3.5mm stereo audio-out
    • 2x I2C ports
    • 14-pin GPIO header
    • Header for motor kill-switch
  • Power — 6-12V battery input for mobile development; 5V regulated input for desktop development; supports 20A (balanced)
  • Operating system — Alphalem OS (Linux) BSP supplied; supports other ARM Linux distributions

The Alphalem OS distribution fits on a microSD card, and includes device drivers for cameras, USB WiFi adapters, and other robot-friendly functions. It also features an onboard robotics development environment with a command-line terminal interface transmitted via a serial port.

Key Alphalem components are said to include:

  • Arduino-style programming environment with support for programming languages including C, C++, and Python
  • Master Control Program (MCP) task manager
  • Message-passing API in multi-process applications
  • Standard Linux filesystem supporting “just about any Linux software that can be cross-compiled for ARM”
  • Libraries for common processes such as I2C communication, face detection, and sensor reading

Alphalem OS is open source, but the hardware designs are not yet open. According to the Rex FAQ, however, “we’ll be publishing enough information that you would be able to build compatible devices and adapt any other Linux distribution to it.”

Project video

The Rex project’s video appears below.

Rex project video

Further information

The Rex is available for Kickstarter funding in packages starting at $99. For $2,000, you get a fully assembled hexapod “Toby clone” robot based on the Rex. More information may be found at the Rex Kickstarter page, where the funding round concludes on Feb. 1.

Update on Jan 21: In answer to a backer’s question, “Do you have any back ups plans if this does not reach 100%?,” posted to the Rex Kickstarter page today, Alphalem replied: “If the kickstarter failed, we will inform the next course of action to all the backers. This will probably include completing the development cycle of REX and then opening up an online store ourselves.”

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One response to “Tiny hacker SBC offers robot-friendly Linux distro”

  1. Guillaume GASNIER says:


    The DM3730 also drives the Linux handheld console Pandora:

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