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gta02-core is a community project to create a new hardware revision of the gta02 hardware, christened and introduced by werner in a mail[1] to the gta03 list

Development discussions are happening on the gta02-core mailing list, and archives can be found here [2] and older entries are on the gta03 mailing list. All the project files (schematics and component models etc.) are stored in openmoko's public SVN server at [3]

Pre-built PDF and Postscript files for quick access to the latest schematics, component drawings, etc., can be found here.

Key pages on:
Neo FreeRunner


What is gta02-core?

gta02-core is an experimental project to explore community involvement in the development of hardware for potential future open phones. The aim is to develop an incremental improvement on existing GTA02 designs, while replicating the necessary CAD files in a open format.

The primary improvement over the GTA02 design will be removal of the Glamo graphics device, relying on the S3C2442's direct LCD interface. This removes the minimal graphics acceleration offered by the Glamo with the benefit of vastly improved bandwidth. This is expected to allow better software graphics acceleration, and easier streaming of video data from SD cards. While some individual (currently accelerated) operations may be slower without Glamo, it's expected that Glamo removal will overall offer a performance increase.

In detail, the hardware changes planned for gta02-core are:

  • Remove Glamo
  • Replace the tri-band Calypso chipset with a quad-band module
  • Remove the audio amplifier
  • Remove NOR
  • Remove one accelerometer and connect both interrupts of the remaining one
  • Move LCM to CPU interface (as used in GTA01)
  • Move Wifi to SPI (see Werner's rework)
  • Remove U4401 etc. (external GSM serial access through headphone jack)
  • Remove the external GPS antenna connector and simplify the GPS RF circuit accordingly

The gta02-core project is primarily a test-bed for the community development process. While it's hoped to take the process through working prototypes, the project is not intended to result in a mass-production phone.

If the community succeeds in the gta02-core project, development of a GTA03 may follow similar lines with community involvement in specifying, designing and developing the hardware.

What is gta02-core NOT?

gta02-core is not gta03. It's not a 'next gen' phone from openmoko. It's not a significant departure from existing gta02 devices. It won't even be a usable phone...

Many hardware changes have been proposed for gta03, gta02.5 or gta02-core. The following hardware changes have been proposed, but are NOT part of the gta02-core plan:

  • adding a camera
  • radical GSM modernization (i.e. no 2.5G or 3G)
  • de-NANDification (but NAND use for anything but storing Qi and "factory" data is discouraged)
  • changing WIFI chip
  • replacing the SoC with a 6410
  • integration of IDBG
  • changes to the ID (case)
  • a multi-touch screen
  • SIR / CIR
  • additional I/O connectors

Basically - the "new ground" we are breaking is in the project and the organisation, not in the device we are producing. The hardware that comes out the end is intended to NOT be a significant step away from work already done, allowing us to focus on the process, over new technical challenges.

Plan and Progress

(simplified from the workflow diagram)

  • Create and review component diagrams ( Component List )
  • Create and review Schematics
  • Create and review device footprints
  • Create and review layouts
  • Produce PCBs
  • SMT / populate PCBs
  • Test
  • Party!

The PCB production and populating will need to be conducted by third party businesses, and the gta02-core project will need to find funding to support these activities.

How can I help?

Join the gta02-core mailing list. Grab a copy of KiCAD and get on with reviewing or submitting changes. Most of the current effort involves comparing our schematics to datasheets and to the GTA02 schematics released by openmoko. We also have an IRC channel called #gta02-core on

Tasks we need help with now:

  • Review schematics symbols against the published schematics and against data sheets.
  • Help drawing the schematics.
  • Follow the discussions in the gta02-core project and review our decisions, policies, and conventions.
  • Implement extensions to KiCad (C++) we discover to be desirable for this project. Here is a "wish list".
  • Find PCB makers who are already familiar with KiCad (or willing to learn), find out if they could produce a board of this complexity, and get a quote.
  • Find SMT factories who are already familiar with KiCad (or willing to learn), find out if they could produce a board of this complexity, and get a quote.
  • Help to set up an organization that can act as an umbrella for activities related to gta02-core and beyond. For example, a voluntary association (e.g., eV or similar).
  • Find sponsors for PCB, SMT, or activities/individuals/roles.
  • Review the schematics.
  • RF experts: help with the GPS and maybe GSM schematics.
  • Help finding or creating component footprints.
  • Review footprints against data sheets and published Gerber files.
  • Help making the layout.
  • RF experts: help with the GPS and maybe GSM layout.

Tasks we will need help with in a few days:

  • Review the layout.
  • Help spreading the word. The project is still in its infancy, but is taking shape quickly.
  • Prepare the software bringup procedure, including flashing NAND from JTAG.
  • Prepare the Linux system (boot loader, kernel, and basic user space) for running on gta02-core.

Tasks we will need help with in a few weeks:

  • Organize the logistics of PCB making, including placing the order, making the data available, handling payment, and shipping.
  • Verify the PCBs for connectivity and general production quality.
  • Organize the logistics of SMT making, including placing the order, making data and components available, handling payment, and shipping.
  • Verify the boards as they come from the SMT line (at the SMT factory).
  • Make the Linux system (boot loader, kernel, and regular user space) run properly on gta02-core.


  • Help drawing schematics symbols. (2009-06-12)

Largely done, but with a long tail:

  • Review schematics symbols against the published schematics and against data sheets.
  • Write a footprint editor (fped) that is more friendly for reviews than KiCad's built-in editor

Getting started

The getting started guide for gta02-core is located in our repository.

If one just wants to keep track of the project this blog might be interesting.

Useful tutorials for using kicad are available here and here

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