A simple PRU input example. This program runs on PRU1 and waits for P8.28 to go high and then pulls P8.29 high.
A switch should be placed between the 3.3V and P8.28. An LED should be placed in series with a 1k resistor between P8.29 and ground.
An updated device tree compiler may be needed:
wget -c https://raw.githubusercontent.com/RobertCNelson/tools/master/pkgs/dtc.sh; chmod +x dtc.sh; ./dtc.sh
The PRU Drivers must be installed also.
The HDMI must be disabled by adding the following line to /boot/uEnv.txt
optargs=quiet capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN
The following will compile all the code for the PRU and main cpu:
make
Compile the device tree overlay and enable it:
cd device-tree
make enable
./input