Re: [Gumstix-users] Addressing custom ICs

[Dave H. <dhy...@gm...>]

Hi Jeremy,

> I have a custom board of ICs (actually running an m68k microcontroller) that
> I want to map to about 2 MB worth of memory addresses.  Is this possible
> with the gumstix (I'm looking at the Verdex)?  Would I do this over the
> 120-pin molex connector?

Yes.

> It seems to have just enough address lines, but
> how do I address it from linux?  How difficult is it to write drivers for
> this in linux - can user space drivers address arbitrary memory locations,
> or would I have to write this into the kernel?

You'll need a small kernel module, which gets the memory region
initialized properly. And if that driver supported mmap, you could
mmap the region into user-space and do all of the communication from
user-space.

> Is there any thorough documentation or examples on using the molex connector
> for custom stuff?

I don't think so. You can look at the schematics for the
netwifimicrosd board and the netCF-vx boards.

The PXA270 datasheet will have most of the information you need.

I know that the two boards I mentioned above have CPLD's on them. I'm
not quite sure what the exact purpose of this CPLD is. Perhaps Gordon
could chime in.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/