Oct 08, 2016, hellekin
As we're getting closer to the layout for proto_v2, we prepared the following summary of Neo900 design to describe its structure and mechanical constraints. But before that...
Neo900 is now an official [IRC] group on Freenode!
This not only means that we now really "own" all Neo900 related
channels so they are safe from possible "hostile takeovers", we also
may now assign 'cloaks' (virtual hostmasks) to team members and
supporters of the project. A cloak is the assigned right part after
"@" of the full username in IRC. So instead of
see for example
~jr@neo900/coreteam/joerg when you do a
joerg-neo900 or hover over the nickname with the mousepointer.
The design consists of three boards, as shown in the drawing on the first page of the Neo900 IO Expanders white paper.
We reuse the case of the Nokia N900, and the shape of LOWER and [BOB] (Break-Out Board) is determined by this. The "bounding box" of LOWER is 106 x 56 mm.
The goal for now is to make what we call the "v2" prototype, where UPPER can be as large as we like. After that, the UPPER for the final product will be similar in shape to LOWER but a little smaller.
We maintain an interactive block diagram that illustrates to which board the various subsystems will go. Here is a snapshot of our schematics. You can download a snapshot of the design files, that live in the following repository: https://neo900.org/git?p=ee
The final product will have an OMAP DM3730 processor, memories, etc., but for v2 we keep things simple and use a Beagleboard-xM as external "brain", and just implement the peripherals.
We expect the final UPPER to need 8 layers, due to the 515-pin 0.4 mm BGA of the OMAP. UPPER of v2 should be considerably easier. We expect LOWER to need at least 4, probably 6 layers. BOB is simple and 4 layers should be plenty. All boards should be 0.8 mm.
This video shows an earlier prototype (only LOWER, basically just modem and a few switches):
A later mechanical-only prototype, showing dummy UPPER and LOWER boards:
The Neo900 project aims to provide a successor of N900 Nokia Internet Tablet™ device, with faster CPU, more RAM and LTE modem, basing efforts on an already existing, mature and stable free platform - the OpenPhoenux GTA04, following the spirit of freedom known from Openmoko devices.