On Tue, Apr 29, 2014 at 09:53:05PM +0200, Ralf Friedl wrote: > Sascha Hauer wrote: > >This adds applets for manipulating gpios under Linux via sysfs. It uses > >the /sys/class/gpio API to set direction and value of gpios and to read > >back the actual value. The applets work like the corresponding C functions > >in the kernel: > > > >gpio_set_value <gpio> <value> > >gpio_get_value <gpio> > >gpio_direction_output <gpio> <value> > >gpio_direction_input <gpio> > > > ><gpio> is the Linux gpio number and <value> is 0 for low and 1 for high. > >gpio_get_value will report the value to stdout. > > > >If not already exported the applets export the gpio via > >/sys/class/gpio/export. After usage the gpio is unexported again, > >but only if it wasn't exported before calling the applet. > What is the advantage of these applets compared to a direct echo to > /sys/class/gpio/... ?
The applets are easier to use and provide better error handling. To export a gpio and set its value it would require two operations: echo 10 > /sys/class/gpio/export echo high > /sys/class/gpio/gpio10/direction Both operations can fail, so you need error checking for both. With the applets you could write gpio_direction_output 10 1 || exit 1 Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
