Cannot enable PRU on Beaglebone Black

Question

I am trying to enable the PRU module on my BeagleBone Black, but I came across two errors. The first one, is when I am trying to activate it:

echo BB-BONE-PRU-01 >/sys/devices/bone_capemgr.9/slots

and I get this error:

-sh: echo: write error: No such file or directory

And the second one comes up when I try to run a simple example, like this:

./PRU_memAccessPRUDataRam

with this error:

./PRU_memAccessPRUDataRam: error while loading shared libraries: libprussdrv.so: cannot open shared object file: No such file or directory

Ho you have any ideea on how can I resolve this two issues? Thank you!

Answer 1

Re first question: check whether your file system has /sys/devices/bone_capemgr.9 or /sys/devices/bone_capemgr.8. Many use the command: >sudo echo BB-BONE-PRU-01 >/sys/devices/bone_capemgr.*/slots, so it doesn't matter; note also the need for sudo unless you have previously done a sudo su or have logged in as root (not normally recommended).

Re second question: it may be related to first problem. Also, see: http://www.element14.com/community/community/knode/single-board_computers/next-gen_beaglebone/blog/2013/05/22/bbb--working-with-the-pru-icssprussv2. As explained in Step 1), do an >lsmod to see if pru is enabled. If not, you can do a >modprobe uio_pruss or better, change the device tree loaded at bootup (am335x-boneblack.dtb) to have the pru parameter status = "disabled" changed to status = "okay". The link above, authored by Shabaz, is the most useful and understandable link I have found in about a year (on and off) of working with the BBB; it's well worth going through everything there as a tutorial.