XO-1.75

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The XO-1.75 laptop is a refresh of the XO-1 and XO-1.5 laptops. In our continued effort to maintain a low price point, OLPC is again refreshing the hardware to take advantage of the latest component technologies. This design, while separate from the XO-3 tablet effort, uses the same very low power electrical design. It continues to use the same industrial design and batteries as XO-1. The design goal is to provide an overall update of the system within the same industrial design and external appearance. Overall, the target was to greatly improve the power consumption while reducing the purchase cost.

XO-1.75 machines will ship with a new software release based on Fedora 13 or 14, including both Sugar and GNOME software.

Specifications

Dimensioned Drawing of XO, click to enlarge

The definitive XO-1.75 laptop specification will be available soon. CL1B hardware specification ("CL2" is the model identifier in the manufacturing data for the XO-1.75 hardware).

The specs below are not authoritative, please refer to the PDF version of the spec linked above.

Physical dimensions

• Approximate dimensions: 245mm × 230mm × 30.5mm (see drawing to the right for detailed dimensions)
• Approximate weight with LiFePO4 battery: 1.45KG (~3.20lbs);
• Configuration: Convertible laptop with pivoting, reversible display; dirt- and moisture-resistant system enclosure; no fan.

Core electronics

XO-1.75 is designed around the Marvell Armada 610 system on a chip.

• CPU: Marvell Sheeva ARM (PJ4);
  • CPU clock speed: 800 MHz (superscalar and out-of-order instruction execution);
  • ARM instruction set compatible (including Thumb-2 and Wireless MMX2);
  • ARMv7 architecture compatible;
  • 32 KB L1 I-cache, 32 KB L1 D-cache, 256KB L2 cache;
• The 610 includes hardware video encode/decode, a 3D graphics engine, display controller, USB, SDIO, and other system interface and management functions

• Embedded controller: ENE IO3731;
  • Embedded Controller: IO3731

• DRAM memory: 512 MB DDR3 dynamic RAM;
• Mass storage: 4 GiB NAND flash in an eMMC device soldered to the motherboard.
  • An internal full size SD card is provided for repair/replacement (not user-changeable without opening the unit with a screwdriver);
  • externally accessible full-size SD card slot;
  • No rotating media.

Prototype Motherboard

Display

Main article: Display

• Liquid-crystal display: 7.5” dual-mode TFT display;
• Viewing area: 152.4 mm × 114.3 mm;
• Two "modes" depending on lighting conditions:

(1) Grayscale (B&W) reflective mode: for outdoor use—sunlight-readable; primarily lit from the front by ambient light; high-resolution (200 DPI), 1200(H) × 900(V) grayscale pixels; power consumption 0.1–0.2Watts;

(2) Color, backlight mode: for indoor use; primarily lit from behind by the LED backlight; built in sub-pixel sampling of the displayed color information results in a perceived resolution of approximately 984(H) × 738(V); power consumption 0.2–1.0Watts;

• The display-controller chip (DCON) formats data for the display.

Note: web browser images are currently scaled up so that an image of very roughly [800 × 600] fills up the browser window.

Integrated peripherals

• Keyboard: 80+ keys, 1.0mm stroke; sealed rubber-membrane key-switch assembly;
  • Keyboard Layouts
  • Layout pictures: English, Arabic, Thai, West African (Nigeria), Portuguese, Spanish, Amharic, French, Urdu, Cyrillic, Turkish (not final), Nepali, Mongolian, Kazakh, Devanagari, Uzbek, Pashto, Dari, Pulaar (Fula), Italian
  • A non-membrane "traditional" keyboard is also available.
• Gamepad: Two sets of four-direction cursor-control keys;
• Touchpad: Capacitance touchpad
• Audio: Internal stereo speakers and amplifier; internal monophonic microphone; jacks for stereo external headphones and microphones.
  • Realtek ALC5631 audio codec (I2S)
• Camera: integrated color video camera; 640 x 480 resolution at 30 FPS;
  • Independent (and undefeatable by software) display of microphone and camera recording status;
  • The camera and device driver support disabling AGC and automatic color balancing, to enable its use as a photometric sensor for educational applications;
  • Omnivision OV7670
• Wireless Networking: Integrated 802.11b/g (2.4GHz) interface; dual adjustable, rotating antennas support diversity reception;
  • Marvell 88w8686 WLAN module, with SDIO interface, on removable module;
  • Remains powered while the laptop suspends, waking the laptop if a packet addressed to it arrives.
  • Ad-hoc networking and 802.11s mesh support available
• Accelerometer: ST LIS33 three axis accelerometer
• Status indicators:
  • Power, battery, Wi-Fi, one software controlled (intended for onboard flash access), visible with lid open or closed;
  • Microphone In-Use, and Camera In-Use, visible when lid is open.

External connectors

• DC power: 6mm (1.65mm center pin) connector; 11 to 24 V input usable, –32 to +40V input tolerated; power draw limited to 25 W; - see power connector dimensions at Battery and power.
  • Maximum Power Point Tracking alters voltage/current for maximum battery-charging power from solar panels
• Headphone output: standard 3.5mm 3-pin switched stereo audio jack;
• Microphone input: standard 3.5mm 3-pin switched stereo microphone jack; selectable 2V DC bias; selectable sensor-input mode (DC or AC coupled);
• USB: Three Type-A USB 2.0 connectors; Up to 1A power supplied (total, available through a single connector);
• Flash Expansion: full-size SD Card slot.

Connectors

Battery

• Pack type: 2 cell LiFePO4, approx. 6V series configuration;
• Capacity: 22 Watt-hours (LiFeP);
• Fully-enclosed “hard” case; user removable;
• Electronics integrated with the pack provide:
  • Identification;
  • Battery charge and capacity monitoring chip (Maxim DS2756 data sheet);
  • Thermal and over-current sensors along with cutoff switch to protect battery;
• Minimum 2,000 charge/discharge cycles (to 50% capacity of new).

See Laptop Batteries or more information.

BIOS/loader

On XO-1.75, there are two different firmwares installed:

• A small bootloader written in Forth and interpreted by CForth runs on the security processor
• Open Firmware runs on the main (PJ4) processor

The bootloader run by the CForth interpreter on the security processor is responsible for initializing the SoC pins and the main memory. It then loads Open Firmware into main memory and starts it executing on the main processor. This CForth bootloader then continues to execute on the security processor, processing input from the keyboard and touchpad.

Open Firmware (OFW) initializes the system peripherals, then loads the OS kernel into memory and starts executing it. OFW also includes hardware diagnostics.

• A dedicated 1 MiB SPI-interface flash ROM contains both CForth (first 128KB) and OFW;
• Hardware support is provided to prevent reprogramming of the OFW flash ROM by malicious software;

Environmental specifications

• Temperature: 0 to 50 degrees Celsius (operating); -20 to 60 degrees Celsius (non-operating)
• Humidity: UL certification planned to IP42 (perhaps higher) when closed, the unit should seal well enough that children walking to and from school need not fear rainstorms and dust;
• Maximum altitude: –15m to 3048m (14.7 to 10.1 PSIA) (operating), –15m to 12192m (14.7 to 4.4 PSIA) (non-operating);
• Shock 125g, 2ms, half-sine (operating) 200g, 2ms, half-sine (non-operating);
• Random vibration: 0.75g zero-to-peak, 10Hz to 500Hz, 0.25 oct/min sweep rate (operating); 1.5g zero-to-peak, 10Hz to 500Hz, 0.5 oct/min sweep rate (nonoperating);
• 2-3mm plastic walls (1.3mm is typical for most systems).

Regulatory requirements

• The usual US and EU EMI/EMC (electromagnetic-interference and electromagnetic-compatibility) requirements;
• The laptop meets IEC 60950-1, EN 60950-1, and CSA/UL 60950-1 (safety) specifications. It also complies with UL 1310 and UL 498. In order to guarantee the safety of children using the laptop, it passes ASTM F 963 (Standard Consumer Safety Specification on Toy Safety, 2003 edition);
• The external power adapter complies with IEC, EN, and CSA/UL 60950-1;
• The removable battery pack complies with IEC, EN, and CSA/UL 60950-1 and UL 2054;
• RoHS (Restriction of Hazardous Substances Directive – EU) compliant.

Block Diagram

Software

See XO_1.75_B1#Software_Support.

More Information

• XO-1.75 B1 pre-production prototype
• Firmware
• Open Firmware ARM Startup
• Software builds

Serial Adapter

Third generation serial adapter.

For firmware, operating system and kernel debugging a serial adapter is required. We are using our third generation serial adapter with the XO-1.75, which has 3.3V serial on the target side, and a USB B socket on the host side.