Cross Roads

Joel Sherrill joel.sherrill at
Tue Oct 23 16:31:39 UTC 2007

Michael.Friedrichs at wrote:
> List,
> I am at a cross road, need some input.
> I have used embedded DOS for previous embedded controller projects.  
> This time I need something more portable, this could be a X86, Coldfire, 
> etc.
> I'm starting the project using a Pentium III, with a PC104 board mounted 
> onto the target board, which has all of my I/O.
> User interface via monitor and keyboard.
Easiest via stdio.  GUI packages have been ported.
> Datafile transfer via ftp through Ethernet to main computer.
RTEMS has BSD sockets and a number of services which
could help here.  There are both NFS and TFTP clients
which could be used to do this.
> Keyboard interface will be query responses; yes no, stop, start, etc.

Again stdio.
> How would these interfaces and i/o addressing be handled with RTEMS.  
> The adc(s), dac(s), and digital I/O's are addresses through the x86 I/O bus.

I usually encourage people to write functions to encapsulate
accessing these types of devices.  Then call them at whatever
rate is appropriate in a task or on demand as appropriate for
the application.  There is no memory protection (like the embedded
DOS') so it is simple memory or IO mapped accesses.
> The first target board has a floppy interface for loading the program.  
> What OS is needed on the target to transfer the RTEMS program from 
> floppy to file.  What if I have no floppy, do I burn a flash?????
> I will be using a Flash drive instead of the hard drive.
There should be a way in the BIOS to pick your boot devices.
You can boot using any number of standard mechanisms but
I think Grub is probably the most common boot manager used.
I think others use netboot or PXE.  Either of the netboot
options might be good for you since you already mentioned
a server that data would be sent to.  It could also be a
tftp boot server.

PXE is probaby supported in the BIOS so it would just be
a matter of getting the object file for your application into
the right format and location.  I don't know the details for
PXE image creation. Maybe a user can pitch in here.

> Thanks for your help.

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