P9_25_pinmux not found in /sys/devices/platform/ocp ?


I am currently using a BBB with Debian Jessie 8.8 and 4.4.x kernel installed. I was trying to configure the P9_25 pin using the command “config-pin P9_25 gpio_pu” but the BBB keeps throwing me the error

P9_25 pinmux file not found!
bash: /sys/devices/platform/ocp/ocp*P9_25_pinmux/state: No such file or directory

I have loaded the cap-universal-00A0 overlay from this github page


and I believe that it should have created a P9_25_pinmux dir in the /sys/devices/platform/ocp/ which is apparently missing.

I have been working on this for a couple of days already mostly because I don’t know much about embedded system as I’m currently a newbie. Any help would be appreciated. Thanks.

I’m was having the same problem,

P9_26 pinmux file not found!
bash: /sys/devices/platform/ocp/ocpP9_26_pinmux/state: No such file or directory
Cannot write pinmux file: /sys/devices/platform/ocp/ocp

re-flashed the latest debian image yesterday and started working fine again.
Today after an apt-get upgrade it failed again.
Something got broke?


the listed latest is just too old.. Grab the Jessie Monthy snapshot flasher:


debian@beaglebone:~$ config-pin P9_26 gpio_pd
debian@beaglebone:~$ config-pin -q P9_26
P9_26 Mode: gpio_pd Direction: in Value: 0

* it uses u-boot overlays, docs are here:



Thx! I will try that right now.

Everything is working again thanks.

One more question if you have the time:
What is the difference between the “BBB-blank-…” and “bone-…” images?

the blank image still has Cloud-9 IDE service, node.js, node-red and whatnot… what does the blank stand for?


Found the answer in [1] & [2].

[1] - https://groups.google.com/forum/#!searchin/beagleboard/BBB-blank|sort:relevance/beagleboard/SrcUpn9Qzt8/SFi-OnqQCwAJ
[2] - https://groups.google.com/forum/#!searchin/beagleboard/bbb-blank|sort:relevance/beagleboard/cP6KnF0eI6E/g__CVt-cBgAJ

Robert / Jason

Could the BeagleBoard.org Latest Firmware Images page maybe have an update and / or additional section? I seem to come and go with BBB projects, when I start a new project I head for that latest images page – that didn’t work out optimally for me this time. Maybe update it with the jessie monthly snapshot or add it as another section, even though it’s a current images page I’d like to see a section with a link to the nightly builds of Stretch / 9 too. It wouldn’t have to be each image listed, just a pointer to the directory and a sentence on how to navigate it. And a section that explains the different types of images blank, iot, lxqt etc. Actually I’d like to see that as a quick readme in the directories. Couldn’t a small -ReadMe.Txt file be added to the build process to be added to the distribution directories? I see the question of what do the different images mean asked from time to time if not often…

  • Jeff

I ran into the same problem. Turned out that P9_25 is reserved for audio even though it is colored as an “available digital” pin. To free up this pin for usage, modify the overlay configuration file:

nano /boot/uEnv.txt

In this file, uncomment the line that disables audio overlay:


After reboot, I can use P9_25 as intended.