XO-3

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OLPC has begun work on a low cost, low power, robust tablet for use by kids.

The actual dimensions are still in flux, but the display surface will be roughly 8" diagonal, with a 4:3 aspect ratio. The tablet electronics will be based around the Armada 610 ARM system-on-a-chip from Marvell, which is also used in the XO-1.75 laptop.

We are hoping to have working prototypes available for software development and hardware testing and refinement by the beginning of 2012. At this time, it is hoped that production might begin in the latter half of 2012.

XO-3 tablets will ship with a software release based on Fedora 14 or later. Support for Android 4.0 is also intended. While both Sugar and GNOME software intend to support tablet devices, another tablet-specific UI may be provided. XO-3 Photo10.jpg

Specifications

The specs below are not authoritative, please refer to the PDF version of the spec (available soon).

Physical dimensions

XO-3 Cover
  • Approximate dimensions: 194mm × 160mm × 13.3mm
  • Approximate weight: 0.6 kg (~1.2 lbs);

Core electronics

XO-3 is designed around the 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
  • DRAM memory: 512 MB or 1GB DDR3 dynamic RAM;
  • Mass storage: 4 GiB to 16 GiB NAND flash in an eMMC device soldered to the motherboard.
    • an internal microSD card slot for repair/replacement -- requires soldering the microSD bracket;
    • No rotating media.

Unlike many tablets, we are still including an Embedded Controller to handle battery charging and power sequencing (subject to change):

Display

Main article: Display

Integrated peripherals

  • Touchscreen: Projected Capacitance Touchscreen capable of tracking five simultaneous touches
  • 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 antennas;
    • Marvell 88w8686 WLAN module, with SDIO interface, on removable module;
    • Remains powered while the tablet suspends, waking the tablet if a packet addressed to it arrives.
    • Ad-hoc networking and 802.11s mesh support available
  • Accelerometer: ST LIS3 three axis accelerometer
  • Light Sensor: a reverse biased LED.

External connectors

XO-3 Connectors
  • DC power: 6mm (1.65mm center pin) connector; 5 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: One Type-A USB 2.0 connector; Up to 0.5A power supplied.
  • USB OTG: One Type-microAB USB 2.0 connector; Up to 0.5A power supplied, up to 1.8A power consumed.

Battery

  • Pack type: 2 cell LiFePO4, approx. 6V series configuration;
  • Capacity: hopefully around 20 Watt-hours;
  • Integrated into the case; replaceable, but not removable on a regular basis;
  • Minimum 2,000 charge/discharge cycles (to 50% capacity of new).

See Laptop Batteries or more information.

BIOS/loader

On XO-3, 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 IP53 (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 5000m (14.7 to 7 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)

Regulatory requirements

  • The usual US and EU EMI/EMC (electromagnetic-interference and electromagnetic-compatibility) requirements;
  • The tablet will meet 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 tablet, 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

XO 3 Block Diagram.png

Software

There are four distinct pieces of software on the XO-3 tablet:

Software Restrictions

  • the Write activity hangs the tablet when it scrolls, <trac>11321</trac>, <trac>11399</trac>, <trac>11450</trac>,
  • suspend and resume are being worked on <trac>10835</trac> <trac>11194</trac> <trac>11142</trac>, are in build os13, but there are some problems, such as two attempts required to suspend <trac>11194</trac>, corruption of cursor <trac>11491</trac>, inability to use USB after resuming <trac>11369</trac>, loss of touchpad function <trac>11496</trac> <trac>11379</trac>, and slightly higher power consumption because DRAM driver terminators remain on,
  • audio support in the kernel is being worked on, is in build os13, but there are some problems, such as Record will not record audio,
  • graphics performance is not yet tuned, <trac>10830</trac>, and rotate is not yet done, <trac>11115</trac>,

(list last reviewed for os13)

File:XO-3 Photo1

More Information

Past News Articles

Long Past News Articles

Other Tablets

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-3, which has 3.3V serial on the target side, and a USB B socket on the host side. Unfortunately, there is no serial port mounted or easily accessible in production units.

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