The deploy script does not work and is totally wrong. But we can make it work anyway.
First, the prerequsites.
Kernel:
$ uname -a
Linux beaglebone 4.9.82-ti-r102 #1 SMP PREEMPT Thu Feb 22 01:16:12 UTC 2018 armv7l GNU/Linux
You can get this with /opt/scripts/tools/update_kernel.sh.
Now you need to make the PRUs available to the OS via a uboot overlay.
uEnv.txt:
enable_uboot_overlays=1
disable_uboot_overlay_emmc=1
disable_uboot_overlay_video=1
disable_uboot_overlay_audio=1
disable_uboot_overlay_wireless=1
disable_uboot_overlay_adc=1
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-9-TI-00A0.dtbo # note the 4-9, the default uEnv.txt uses the 4-4 file!
enable_uboot_cape_universal=1
I don't know if you need to disable emmc, video, audio, wireless, or the adc. I disabled them because it's 5 less things to debug.
(Actually, I ended up succeeding by only disabling video.)
Reboot.
Now, clone the beaglescope repository and build the firmware:
$ cd BeagleScope/examples/firmware_exmples/pru_blinky/PRU_gpioToggle
$ export PRU_CGT=/usr/share/ti/cgt-pru
$ make
(Note that you may need to link /usr/bin into /usr/share/ti/cgt-pru/bin for Reasons.)
Glorious successful build output:
************************************************************
Building project: PRU_gpioToggle
Building file: PRU_gpioToggle.c
Invoking: PRU Compiler
/usr/share/ti/cgt-pru/bin/clpru --include_path=/usr/share/ti/cgt-pru/include --include_path=../../../include --include_path=../../../include/am335x -v3 -O2 --display_error_number --endian=little --hardware_mac=on --obj_directory=gen --pp_directory=gen -ppd -ppa -fe gen/PRU_gpioToggle.object PRU_gpioToggle.c
Building target: gen/PRU_gpioToggle.out
Invoking: PRU Linker
/usr/share/ti/cgt-pru/bin/clpru -v3 -O2 --display_error_number --endian=little --hardware_mac=on --obj_directory=gen --pp_directory=gen -ppd -ppa -z -i/usr/share/ti/cgt-pru/lib -i/usr/share/ti/cgt-pru/include --reread_libs --warn_sections --stack_size=0x100 --heap_size=0x100 -o gen/PRU_gpioToggle.out gen/PRU_gpioToggle.object -mgen/PRU_gpioToggle.map ./AM335x_PRU.cmd --library=libc.a --library=../../../lib/rpmsg_lib.lib
<Linking>
Finished building target: gen/PRU_gpioToggle.out
Output files can be found in the "gen" directory
Finished building project: PRU_gpioToggle
************************************************************
When the build outputs that many stars you know it's gonna be good.
We are going to run this in PRU0.
Copy the firwmare to the location for PRU0:
$ sudo cp gen/PRU_gpioToggle.out /lib/firmware/am335x-pru0-fw
As an aside, I think you can override this location, but we won't.
Now here's where we go totally off the rails relative to the deploy.sh included with the example. For some reason, it wants to use the P8_45 pin. This pin is not available to PRU0, but P9_31 is:
Make this pin available to the PRU:
$ config-pin P9_31 pruout
Now we just need to tell the PRU to start running that code.
# echo start > /sys/bus/platform/drivers/pru-rproc/4a334000.pru0/remoteproc/remoteproc1/state
It works. You will see your LED blink (or a square wave on your oscilloscope, in my case; 1V/div and 100ms/div is enough). The dmesg will also indicate that something is going on:
remoteproc remoteproc1: powering up 4a334000.pru0
remoteproc remoteproc1: Booting fw image am335x-pru0-fw, size 32820
remoteproc remoteproc1: remote processor 4a334000.pru0 is now up
Why is pru0 remoteproc1? Because there's another remote processor for the power management that is remoteproc0.
Note that if you know in advance that pru0 is remoteproc1, you can
just use /sys/class/remoteproc/remoteproc1 for your control.