stripes
Member
Registered: Sep 1999
Location: VA, USA
Posts: 27 |
Springboards basically get a view of the CPU bus, and two pins that remind them the bus is talking to THEM (chip select 0 and one).
Reading the dev info it looks like CS0 is expected to be memory (a ROM, or FLASH), and in fact the first hundrad bytes or so have to have a special header. It is expected that CS0 have the programs that drive the hardware, or just hold code/data on "ROM only" springboards. It is expected, but not required that CS1 have the hardware interface.
You could make a springboard that used CS0 and passed CS1 onto the next springboard as CS0. You could even fit both your program and your hardware in CS0. Unfortunitly you would only be able to support another Springboard that only uses CS0, not both CS0 and CS1. However I'm not sure who would want something compatable with "most memory springboards, and a few other random things".
Doing anything else would be a rather large kludge, for example send everything on to the "next" springboard *unless* you see 15 reads in a row for the first byte on CS0, then switch to showing your springboard until....
If there were anything intresting you could do without talking to the Palm device (say just suplying power) doing a pass through would be easy, but I'm not sure you could make any intresting devices that way.
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