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SODIMM-sized computer module runs Linux

Jul 27, 2007 — by LinuxDevices Staff — from the LinuxDevices Archive — 26 views

Cogent Computer Systems has begun shipping an SODIMM-sized computer module based on Marvell's XScale PXA270 processor. The CSB726 “system-on-module” (SOM) is available with a development kit that includes a carrier board and a Linux 2.6 BSP (board-support package).

(Click here for larger view of the CSB726 SOM)

The module targets “any size-restricted, low-power, or battery-operated application,” according to the company. Cogent rates the CSB726's power consumption at:

  • 1500mW maximum
  • 750mW typical
  • 15mW during sleep to RAM
  • 10mW when powered down
An on-board Atmel AVR microcontroller manages transitions between battery power and external power. It can reportedly check for wakeup events — RTC alarms or analog/digital inputs — at one-second intervals, even when the system is powered down.

Other specifications of the CSB726 include:

  • Processor — Marvell “Monahans P” PXA270, clocked at 520MHz
  • Memory — 128MB mobile SDRAM
  • Display:
    • Silicon Motion SM501 video controller
    • LCD and CRT output
    • SXGA (1280 x 1024 pixel) video resolution
    • YUV to RGB conversion for MPEG4 decode
  • Storage — 64MB flash, with secure 256-byte sector and 128-bit electronic serial number
  • LAN — 10/100 Ethernet
  • Other I/O ports:
    • USB 1.1 host and client
    • 1 x RS232 serial port (2-wire)
    • 2 x PXA270 UARTS (one 4-wire, one 8-wire TTL)
    • 2 x SM501 UARTS (each 4-wire TTL, shared with SM501 ZV Port)
    • 10 dedicated GPIO lines
    • 2 x SSI/SPI ports
  • DS1338 real-time-clock with external battery input
  • Expansion:
      CompactFlash and SD/MMC interfaces (sockets and buffers are off-board)

    • Edgecard connector — DIMM-200, low profile
  • Dimensions — 2.6 x 2 x 0.3 inches (66.8 x 50.8 x 8 mm)
  • Power — 6V to 30V DC

CSB726 SOM mounted on CSB701 baseboard
(Click to enlarge)

For development purposes, the CSB726 is available with the CSB701 baseboard, shown above. Featuring an SODIMM socket for the CSB726, the 5 x 5.4-inch baseboard provides access to all of the module's signals via 0.1-inch headers. Connectors for 10/100, USB, debug serial, CompactFlash, and SD/MMC are complemented by four I/O sites, providing access to the SOM's serial interfaces.

Other features of the baseboard, according to Cogent, include:

  • 4 Amp Power FET's for switching external or battery power to the main rail (VMAIN)
  • Standard 20-pin ARM processor JTAG header
  • JTAG and expansion headers for the AVR microcontroller (micro on CPU module)
  • Header for attachment of 4-cell 0.5A to 4.0A battery pack
  • Onboard 5.0V @ 4A power supply for I/O site and USB host use
  • Dual SJA1000 CAN 2.0B controllers (interfaced by CPLD), TX/RX routed to I/O sites
  • 41-pin interface to CSB907 LCD displays with SPI (touch), I2C, and power control
  • 20mm coin cell holder (CR2032) for RTC battery backup (RTC on CPU module)
  • Reset, power, and debug switches
  • Power, debug, and battery status LEDs
The CSB726 SOM costs approximately $200, with complete development kits starting at around $1,500. The development kits are shipping now, and come with both a Linux 2.6.16 BSP and a Windows CE 5.0 BSP, a Cogent spokesperson said.

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