activation error of pinmux for pru1

i’m new to using PRU, what i want to do is configure the pins P8.27, P8.28, P8.29 and P8.30 in BBB but i have trouble configuring them. The code i use is the following:


/ {
compatible = “ti,beaglebone”, “ti,beaglebone-black”;

part-number = “EBB-PRU-Example”;
version = “00A0”;

/* This overlay uses the following resources */
exclusive-use =
“P8.27”, “P8.28”, “P8.29”, “P8.30”, “pru1”;

fragment@0 {
target = <&am33xx_pinmux>;
overlay {

pru_pru_pins: pinmux_pru_pru_pins { // The PRU pin modes
pinctrl-single,pins = <
0x0e0 0x0d // P8_27
0x0e8 0x2e // P8_28

0x0e4 0x0d // P8_29
0x0ec 0x0d // P8_30


fragment@1 { // Enable the PRUSS
target = <&pruss>;
overlay {
status = “okay”;
pinctrl-names = “default”;
pinctrl-0 = <&pru_pru_pins>;

After saving this i do the following:

root@beaglebone:~# dtc -O dtb -o EBB-PRU-Example-00A0.dtbo -b 0 -@ EBB-PRU-Example.dts

root@beaglebone:~# sudo sh -c “echo EBB-PRU-Example > /sys/devices/platform/bone_capemgr/slots”

Finally when reviewing the pins their values have not changed…

root@beaglebone:~# cat $PINS |grep ‘56|57|58|59’
pin 22 (44e10858.0) 00000017 pinctrl-single
pin 56 (44e108e0.0) 00000000 pinctrl-single
pin 57 (44e108e4.0) 00000000 pinctrl-single
pin 58 (44e108e8.0) 00000000 pinctrl-single
pin 59 (44e108ec.0) 00000000 pinctrl-single
pin 86 (44e10958.0) 00000037 pinctrl-single

and when i check with dmesg it tells me the following and i do not know what it means:

root@beaglebone:~# dmesg |grep pru
[ 229.784032] pinctrl-single 44e10800.pinmux: pin 44e108e0.0 already requested by 0-0070; cannot claim for 4a300000.pruss
[ 229.794920] pinctrl-single 44e10800.pinmux: pin-56 (4a300000.pruss) status -22
[ 229.802176] pinctrl-single 44e10800.pinmux: could not request pin 56 (44e108e0.0) from group pinmux_pru_pru_pins on device pinctrl-single
[ 229.814713] pruss_uio 4a300000.pruss: Error applying setting, reverse things back

Does anyone know what is happening here?

i would like to understand in detail what happens here. I hope you can help me clarify this, i’m using Linux beaglebone 4.4.145-bone23