Over the past three months, we’ve been working hard to finalize the specs for the Raspberry Pi device, and to produce schematics and a PCB layout. Last Tuesday, we sent an alpha release of the board for manufacture. From an electrical perspective, this board is intended to be identical to the final device; the resulting units will be used to validate the schematic design, and will serve as our interim software development platform.
Key differences between the alpha and final boards are:
- The alpha board is roughly 20% larger than the credit-card-sized final board. As you can see, our size is already dominated by the area of the various connectors.
- The alpha board has six layers rather than four, and uses a variety of expensive HDI features (blind and buried vias, via-in-pad) which we wish to eliminate from the final board.
- The alpha board has various test and debug features which will not be present on the final board.
The ICs used in the design are an ARM-based application processor (center) and an SMSC LAN9512 USB 2.0 hub and 10/100 Ethernet controller (right and down from center). The SDRAM is mounted on top of the application processor in a PoP configuration.
Following the example of the BBC Micro, we intend to launch both a Model A device (lacking the LAN9512, and with 128MB of RAM) at the $25 price point, and a Model B device (including the LAN9512, and with 256MB of RAM) for a $5-10 additional cost. We remain confident of shipping before the end of 2011.
Check back in a couple of weeks to see how the alpha boards turned out.