Sorry, I meant to say Hi Paui, On Fri, Oct 18, 2013 at 3:29 PM, Dave Hylands <[email protected]> wrote:
> Hi Jack, > > > On Fri, Oct 18, 2013 at 3:22 PM, Paul Tan <[email protected]> wrote: > >> Thanks, I'll try to see if there is a difference with libsoc or not. >> However, I did manage to get it working with low level unix i/o (open, >> write) instead of the buffered stream i/o (fopen, fwrite). It works >> correctly, I didn't need a seek operation, and I was able to get pulse >> widths down to 10uS reliably. Interesting difference though: fwrite >> to "/sys/class/gpio/export" succeeds even if GPIO30 was already exported, >> but write to "/sys/class/gpio/export" fails if GPIO30 was already exported. >> > > That's because fwrite is using buffered I/O. If you put the FILE * in > unbuffered mode then you'd find that it would fail too. By default, files > opened with fopen are fully buffered. The buffer size typically around 4K > or so, and the operations that will trigger flusing that data are normally > things like fseek, fread, fflush, or the buffer getting full. The operation > which actually triggers the low-level write will be the one that fails. > > -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com -- 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/groups/opt_out.
