Is this approach useful? http://linuxjunk.blogspot.com/2009/01/beagleboard-gpio-input-driverless.html
--Dale At 7:29 PM -0500 8/29/09, Jon Elson wrote: >Progress report! > >I have gotten the compiler working (have to use g++ for some odd reason) >and it creates >a working executable. I have a demo program for the AVR32, and all I >had to do was >change the GPIO pin in the code and it actually worked. But, it is >slow, about 120 us for each flip >of the port bit. Still, that is pretty encouraging progress! It uses >the device file >/sys/class/gpio/gpio168/value to set the port bit. This isn't real >surprising, guessing at >what the inside of this driver looks like. Also, the test code uses : >rewind (fp); >strcopy(,"1"); >fwrite(,,fp); >fclose(fp); >for each change to the port bit. > >Does anyone know any pointers to docs, examples, etc. on writing device >drivers to >emulate a generic PC parallel port on these embedded environments? I >gather there >is a mechanism to map a group of GPIO ports to memory addresses, and >then the driver >might be quite simple. So, a write to the par port data register would >just become a >byte write to that memory address. > >I tried to write a Unix device driver (actually a printer, in fact) >about 25 years ago, and although it worked, >I used the wrong mechanisms and it was INSANELY slow, maybe a thousand >characters a second. > >I know that a device driver won't be needed for the real time side of >EMC to talk to the port, but I need to make >some user-mode test programs first. On the other hand, instead of a >driver (which would be "neater"), if somebody >knows how to set up the memory mapping of the ports, I could try that. >The docs on Angstrom are pretty thin, >I know how to do a lot of stuff on the X86 architecture like open the >mapping to PC I/O ports with >ioperm() and iopl(), I expect there's some similar facility in Angstrom >for the ARM architecture...... > > >Thanks, > >Jon > >------------------------------------------------------------------------------ >Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day >trial. Simplify your report design, integration and deployment - and focus on >what you do best, core application coding. Discover what's new with >Crystal Reports now. http://p.sf.net/sfu/bobj-july >_______________________________________________ >Emc-developers mailing list >Emc-developers@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
