Re: [Gumstix-users] C-Application to read and write GPIO

[Ahmed R. <eng...@gm...>]

You are right , this is much better one

On Mon, Mar 7, 2011 at 4:27 PM, Patrick Maheral
<pma...@dr...>wrote:

>  That seems like overkill to write a C-application that just spawns off
> another process.  If you plan to use that approach, I'd suggest sticking
> with a shell script.  If you want to be a little more efficient, try
> something like this:
>
> #include <stdio.h>
> const char dirInString[] = "in\n";
>
> int main(int argc, char *argv[])
> {
>     int gpio13Fd;
>     gpio13DFd = open("/proc/gpio/GPIO13");
>     if (gpio13Fd < 0) {
>         perror("Could not open GPIO13");
>         exit (-1);
>     }
>
>     write (gpio13Fd, dirInString, strlen(dirInString);
>
>     close(gpio13Fd);
> }
>
> It's a little longer than your example, but you can do other operations on
> that file (GPIO13) before closing and exiting.  I haven't looked at the
> "/proc/gpio" interface, so I'm not sure what else you can do to that file,
> but I have used the "/sys/..." interface which has multiple files for each
> GPIO (eg. direction, value).  If you want to take one step further, you
> could open "/dev/mem" and mmap GPIO registers (see devmem2), but requires
> root privileges, and may be dangerous if you are not carefull.
>
> Patrick
>
>
>  ------------------------------
>  *From:* Ahmed Ramadan [mailto:eng...@gm...]
> *Sent:* March 6, 2011 06:20
> *To:* General mailing list for gumstix users.
> *Subject:* Re: [Gumstix-users] C-Application to read and write GPIO
> [snip]
>
> thanks, i found it, very simple  :)
> this is my application to control the GPIOs
>
> #include <stdio.h>
>
> int main(){
>
>      system("echo in > /proc/gpio/GPIO13");
> }
> thanks again :)
> --
>  *A.Ramadan
>
> Cellular: +20-12-9961294
> Tel: +202-22392779
>
> *
>
>
>
> ------------------------------------------------------------------------------
> What You Don't Know About Data Connectivity CAN Hurt You
> This paper provides an overview of data connectivity, details
> its effect on application quality, and explores various alternative
> solutions. http://p.sf.net/sfu/progress-d2d
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-- 
*A.Ramadan

Cellular: +20-12-9961294
Tel: +202-22392779

*