Prerequisite Configuration

Device Permissions

Arch does not include and dev rules for Raspberry Pi modules so by default librpip can use nothing. Librpip includes udev rules that can be used as is or modified to suit your requirement . From the source directory copy the ./distro/arch/librpip.rules to /etc/udev/rules.d

Access Groups

All Access Groups referred to in the udev.rules need to be created, e.g.

$ sudo groupadd gpio
$ sudo groupadd spi
$ sudo groupadd i2c

Additionally add the PWM group as used by the librpip-pwm-init script

$ sudo groupadd pwm

Now add the users that require access to the peripherals into the groups by editing /etc/group

PWM init script

Arch uses systemd to launch the librpip-pwm-init script instead of rc.local. From the source directory copy the ./distro/arch/pwm-init.service to /etc/systemd/system 

This is enabled later when PWMs are actually configured.