Balloon hardware overview
The Balloon 3 design process started in 2004, when the PXA270 was chosen as a logical upgrade from the SA1110. Various meetings were held to refine practical aspects of the design like which connectors to use, how to group signals to connectors, and also how to map the pxa270 functionality onto the existing expansion bus, given a multitude of new functions and signals. In the light of unreliablity problems with connectors used on balloon2, due to the weakness of the little pre-crimped leads you get to put in them, Balloon 3 uses FPC/FFC connectors throughout. It also has a built-in 8/16-bit bus (Samosa) for driving any simple devices you might need (IO, displays, logging equipment), and the programmable logic has been much enhanced. You can now have either a CPLD version like Balloon 2, but with more uncommitted logic as much less glue logic is needed external to the CPU, or an FPGA so that it is possible to do fancy DSP-type functionality on-board.
The information below is preliminary and has been derived from the first issue of the data sent for manufacturing the inital prototypes of Balloon 3. The next iteration of the board may look different: although we will endeavour to keep the connectors in the same places, this can't be fully guaranteed at this stage. Any design changes resulting from debugging could have an impact on the placement of parts.
All supplied as PDF files.
Version 0.1 Layout files
Showing component positions and labels
Datasheets for the chips
Clickable board images
Here are images of the very first Balloon3 prototypes, hot off the production line on March 2nd 2006.
Top of v0.1 prototype board - CPLD variant
Top of v0.1 prototype board - FPGA variant
Bottom of v0.1 prototype board