BeagleBone Black Device Tree Overlays Not Applying

Question

I am trying to create a device tree overlay for a BeagleBone Black per these instructions: http://derekmolloy.ie/gpios-on-the-beaglebone-black-using-device-tree-overlays/. I followed the directions exactly as shown and was not told of any errors, except after I try to apply the overlay (with echo DM-GPIO-Test > $SLOTS), it doesn't seem to actually work. Using cat $SLOTS shows everything how it is supposed to be:

root@beaglebone:/lib/firmware# cat $SLOTS
 0: 54:PF--- 
 1: 55:PF--- 
 2: 56:PF--- 
 3: 57:PF--- 
 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
 6: ff:P-O-L Override Board Name,00A0,Override Manuf,DM-GPIO-Test

However, if I cat $PINS none of the values have changed from the original, and the dmesg command does not return any of the expected output (shown on the linked site). I have also looked at several other sites about overlays, with more or less the same instructions, which are also unsuccessful. I've tried other overlays as well, and tested on multiple BeagleBone Black boards, with no success.

I am using the 3.8.13 kernel with Angstrom, essentially unmodified except for what's in that tutorial.

Answer 1

you have to run the command as root.