Hi Julian, All,
I think I've figured out the [gpio] external. It works fine, but there there is no documentation, however, the .c file is not very complicated.
The test-gpio.pd file is not very good as documentation, so I am attaching a draft help file.
The argument of [gpio] is the pin number. The first thing to do is [enable 1( and not [open 1(, which is equivalent to the:
sudo echo "17" > /sys/class/gpio/export
command.
Then [open 1(, then [output 1/0( to choose direction and then write (float) to or read (bang) from the pin...
There are still a few more things I need to discover, but more tomorrow when I have some jumper cables and feel more awake.
best,
J