On 1/12/2014 2:44 PM, Thomas Studwell wrote: > Charles, I didn't see any reference to 'high' being a valid 'direction' > using the virtual GPIO pins, so I added these to the end of the setup.sh > file. If I get time later today or tomorrow, I'll update the script to > process an optional 'level' parameter to the pin list rather than > hardcoding it like this. > > Included text: > sudo -A su -c "echo 1 > /sys/class/gpio/gpio44/value" > sudo -A su -c "echo 1 > /sys/class/gpio/gpio46/value" > sudo -A su -c "echo 1 > /sys/class/gpio/gpio48/value"
Making me provide references, eh? Well, OK: https://www.kernel.org/doc/Documentation/gpio/gpio-legacy.txt ...scroll down to "Paths in Sysfs" where you will find: /sys/class/gpio/gpioN/ "direction" ... reads as either "in" or "out". This value may normally be written. Writing as "out" defaults to initializing the value as low. To ensure glitch free operation, values "low" and "high" may be written to configure the GPIO as an output with that initial value. Note that this attribute *will not exist* if the kernel doesn't support changing the direction of a GPIO, or it was exported by kernel code that didn't explicitly allow userspace to reconfigure this GPIO's direction. -- Charles Steinkuehler char...@steinkuehler.net
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