WS2812 PRU driver, tested on Beaglebone Black kernel 4.19
Since Beaglebone moved away from the PRU uio / kernel overlays, libraries like LEDscape no longer work.
This library is a minimal working example tested on a PRU rproc kernel (4.19). Currently, it only supports a single pin output (P9_31), but could be easily extended to do multiple in parallel.
Disable HDMI and reboot
sed -i 's/#disable_uboot_overlay_video=1/disable_uboot_overlay_video=1/' /boot/uEnv.txt
reboot
Build and install the PRU driver
cd pru && make && sudo make install
This copies our ledpru-fw to /lib/firmware.
Configure our pin to be a PRU output:
config-pin P9_31 pruout
Start the PRU driver:
sudo make config # Tells the kernel about our new firmware
sudo make run # just sends "start" to the rproc and starts our PRU program
Plug in the LED strip you want to P9_31 header pin on the Beaglebone.
Build the ledpru userspace driver library
cd ../
make
Maybe run a test pattern if ya want
make test
sudo ./test
Happy hacking!
TODO: support multiple channels. Should be able to get ~16 or so from each PRU. Probably use https://github.com/fyhertz/epilepsia if you want to get serious though. This is just a quick and dirty hack to get a single strand working.