<Sigh!> I *do *tend to think in terms of basic microcontrollers where you have to make every clock cycle count. It looks like BBB is going to give me the luxury of clock cycles to spare.
>From what I can gather, though, part of the problem in accessing the processor registers directly is that you'd have to run as root. Wouldn't you have the same problem with PRU access? On Monday, August 18, 2014 3:46:44 PM UTC-4, William Hermans wrote: > > If you have something that just needs to switch something on / off once in > a while( less than 200 Hz ) why would you need to complicate things ? > > If you need fast though, a PRU + mmap can achieve fairly "insane" speeds. > 10Mhz or better should not be a problem. > > > On Mon, Aug 18, 2014 at 12:18 PM, Tim Cole wrote: > >> So, I'm guessing it's a case of sacrificing performance for portability >> and robustness. My first reaction is that it seems odd, but then again --- >> make it work before you make it faster. >> Thanks! >> >> >> >> On Monday, August 18, 2014 1:54:39 PM UTC-4, Jerônimo Lopes wrote: >> >>> I think... >>> >>> It's one of UNIX system base, that everything is a file. >>> It is a common way of doing things in different platforms. For example: >>> gpio registers in 8051 are different from PIC, and different from AVR, and >>> so on. On a Linux (at least at user space), there is a common interface to >>> access gpio. Gives you much more portability. You can run the same code in >>> different processors. >>> >>> Jerônimo Lopes >>> >>> >>> >>> 2014-08-17 1:01 GMT-03:00 Tim >>> >>>> Greetings all, >>>> >>>> I've been playing with software and hardware for 30+ years, but I'm new >>>> to Linux and embedded Linux systems. The code snippets I've been able to >>>> find for GPIO access all seem use file I/O functions. I've never seen this >>>> approach before -- I'm accustomed to reading and writing processor >>>> registers. The file I/O approach seems strange to me, but I'm new here, >>>> and >>>> there's a *lot *that seems strange. >>>> >>>> So, can someone explain why the file I/O approach is used? Is this a >>>> typical technique for Linux systems, or something particular to ARM >>>> processors? I suppose it doesn't really matter, but I prefer to understand >>>> why things are done as they are. >>>> >>>> Thanks very much, folks. >>>> >>>> Yours in newness, >>>> Tim >>>> >>>> -- >>>> For more options, visit http://beagleboard.org/discuss >>>> --- >>>> You received this message because you are subscribed to the Google >>>> Groups "BeagleBoard" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected] <javascript:>. >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> For more options, visit https://groups.google.com/d/optout. >> > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
