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$80 module runs Linux

Jul 13, 2009 — by LinuxDevices Staff — from the LinuxDevices Archive — 6 views

The Swedish company Strategic Test has announced a SODIMM-sized processor module using Freescale's recently announced i.MX25 SoC (system-on-chip). The Linux-compatible “Tx-Star” features a 400MHz i.MX257, 64MB of RAM, 128MB of flash, and an LCD controller, and is available with an evaluation baseboard.

Strategic Test says the Tx-Star will sell for approximately $80 in the U.S., and touts it as the industry's "lowest-priced system on module that is capable of running standard OSes such as Linux and Windows CE." The company also cites a "world's first," though we believe that the Tx-Star is basically identical to the Denx TX25 that was announced last week.

Strategic Test's Tx-Star

(Click to enlarge)

The German company Ka-Ro Electronics has produced a series of SODIMM-sized processor modules that have been remarketed in the past by others including both Strategic Test and Direct Insight. For example, Ka-Ro previously released the TX37, a module based on Freescale's i.MX37 SoC, the TX27, a module based on Freescale's i.MX27, and modules using Marvell XScale processors — the Triton-320, Triton-270, and Triton-255. The new Strategic Test Tx-Star (and last-week's Denx TX25) both appear to be identical to Ka-Ro's TX25 module.

By whatever name, the module includes a Freescale i.MX25 processor clocked at 400MHz, 64MB of RAM, and 128MB of flash memory. The i.MX257 SoC used in the Tx-Star is one of two high-end industrial versions of the i.MX25 design. The SoC provides basic connectivity options along with an LCD controller, resistive touchscreen controller, camera sensor interface, two smartcard interfaces, two CAN interfaces, and an ESAI interface for audio applications (see diagram below). An i.MX258 version is identical except that it adds an on-chip security engine and "highly specific" tamper detection circuitry.

Freescale i.MX257 block diagram
(Click to enlarge)

Like the earlier modules listed above, the Tx-Star/TX25 uses a SODIMM form factor of just 2.6 x 1.0 x 0.16 inches, and is designed to be plugged into a development baseboard. Interfaces, all of which reach the outside world via the SODIMM connector, include 10/100 Ethernet, USB 2.0 On-The-Go, USB 2.0 host, dual SDIO ports, audio, a display interface, and support for a 5 x 5 keypad, Strategic Test says.

Strategic Test notes that unlike the other Ka-Ro-derived SODIMM modules, the Tx-Star uses standard DDR memory rather than mobile SDRAM. As a consequence, its power consumption is a little higher, at approximately 0.5 Watts, the company says.

Features and specifications listed by Strategic Test for the TX-Star module (and by Ka-Ro for the TX25) include:

  • Processor — 400MHz Freescale i.MX25
  • Memory — 64MB mobile DDR-SDRAM (expandable to 128MB), and 128MB of flash storage
  • Display — Supports up to 800 x 600 via 24-bit LCD interface
  • Networking — 10/100 Ethernet
  • Storage — PATA interface
  • Other I/O and expansion interfaces:
    • 5 four-wire UARTS
    • Camera interface
    • USB 2.0 host
    • USB 2.0 device
    • I2C
    • 2 x SSI/AC '97/I2S
    • 2 x CAN
    • 2 x SDIO
  • Power supply — 3.3V power supply with sources including 1-cell Li-Ion/Polymer battery (3.0V to 4.2V); 5.0V USB supply; AC wall adapter
  • Dimensions — 2.6 x 1.0 x 0.16 inches (67.6 x 26 x 4.2mm)
  • Operating temperature — -40 to 185 deg. F (-40 to +85 deg. C)

The Development Kit-5 baseboard

According to Strategic Test, the Tx-Star is compatible with the previously available Development Kit-5 baseboard (manufactured by Ka-Ro, and marketed by Direct Insight and Denx too). Featuring a SODIMM socket for the TX37 module, the baseboard also has two additional slots for SD cards.

The Development Kit-5 provides real-world connectors and headers

(Click to enlarge)

As shown in the photo above, the Development Kit-5 provides standard connectors for a 10/100 Ethernet connector, VGA, USB 2.0 host and device, an RS232 serial port, and a 3.5mm headphone jack. The board also has a 10-pin header for a second serial port, plus a 40-pin connector that can be used to connect an optional 7-inch touchscreen display with 800 x 480 resolution, Ka-Ro says.

Features added by the Development Kit-5 development board are said to include:

  • 2 x SD card slots
  • USB 2.0 host and device connectors
  • VGA port with D-SUB connector
  • 10/100 Ethernet port
  • 3.5mm headphone jack
  • 2 x RS232 ports (one with 9-pin connector, one with 10-pin header)
  • Camera interface
  • JTAG interface
  • Dimensions — 6.3 x 3.9 inches (160 x 100mm)

Bob Giblett, President of Strategic Test, stated, "We are very excited about the TX-Star as this is the lowest priced 32-bit system-on-module that is capable of running standard OSes such as Linux and Windows CE. For companies currently using 16-bit MCU's who are strangled by performance and lack of code transportability, we believe the Tx-Star offers a terrific alternative in this economic climate."


Strategic Test did not announce a release date for the Tx-Star, but the device appears to be available now, along with the existing Development Kit-5 baseboard. Pricing starts at approximately $80 in single quantities, the company says. More information may be found on the Strategic Test website, here or Ka-Ro Electronics website, here.

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