Ron Bean wrote:
> I read somewhere (maybe on the Gumstix site) that the easiest way to set
> them up is to recompile the bootloader, and have it set them up the way
> you want them. The Beagleboard expansion cards have a ROM that tells the
> bootloader how to set things up, which is nice if you're planning to
> swap out the expansion cards often (as opposed to setting it up for one
> particular use).
>   
Yes, but that was more complicated, and made a semi-permanent change.  
If you do it wrong, it can "brick" the board, and you need to reload the 
bootloader from the serial port, I think.  A rather complex procedure.  
If you do it wrong in a Linux user-mode program, you crash the system 
and need to reboot.  So, I have the whole scheme worked out to do it 
from a privileged user-mode program.  I assume that since this program 
just writes to memory-mapped I/O port addresses, it should work exactly 
the same as an RT kernel module.

I have enough doped out to have made a working PC parallel port adapter 
board that will do regular parallel port or EPP port operations.
And, I have some routines that could be turned into a pretty exact 
parallel port emulator without a lot of effort.  You'd just need to 
provide a wrapper that overloads the INB and OUTB macros with calls to 
that function, and other than a special include file that provides these 
INB and OUTB macros, not a line of EMC2 would need to be changed.  (Or, 
at least, I think it could be done that simply.)

The RTAI port that Torsten Koschorrek is working on should be 
transparent to either system.  I would assume it can figure out the 
actual real time clock from /proc/ info or something, so it will provide 
correct scheduling on machines with different clock speeds.

Jon

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