Syntax for dts file error. Trying to make an overlay for connecting to PRU R30 register

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1

I can’t find my old post, so I apologize for any repeat post.

I am trying to allocate two pins (P8_12,P8_46) to PRU0 and PRU1. So effectively mode 6 and mode 5. I want to exclusively use these by the pru(s). Still trying to understand this device tree overlay, but I found an example one and modified it. It gives a syntax error when ti toy to compile it (dtc). After beating my head against the wall, I am hoping a second set of eyes will be helpful. Any help one can give on the syntax error (and if the dts file won’t accomplish what the desire for these pins).

`

/*

2

Ok, so I got it working, so will post in case others face the same issue. First, the syntax issue was a missing “;” after the exclusive use tag. Also, I had some references using the wrong labels. What wold be great if a write up on the current use and sections of the device tree for the beaglebone black. Right now one must be knowledgeable in all things (PRU assembly, mapping memory to a arm program to read/write, tools to build the PRU, how to activate it, and finally device tree). Although I know the basic concept of the device tree, known what to put for the sections (PRUSS, am355x, etc) and the keywords are still very much a mystery. Hard to be knowledgable in all things and keep it a hobby). Luckily I didn’t have to disable items (although the next project I will). Anyway, this file appears to have worked:

`

/dts-v1/;

/plugin/;

/{

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

part-number = “DIYBLIGHTS”;

version = “00A0”;

exclusive-use = “P8.12,P8.46”;

fragment@0 {

target = <&am33xx_pinmux>;

overlay {

diyblights: pinmux_pru_pru_pins {

pinctrl-single,pins = <

0x30 0x06 /* P8_12 GPIO:44 $PINS:12 MODE 6 -pru0 R30_14 */

0xA4 0x05 /* P8_46 GPIO:71 $PINS:41 MODE 5 - pru1 R30_1 */

;

};

};

};

fragment@1 {

target = <&ocp>;

overlay {

test_helper: helper {

compatible = “bone-pinmux-helper”;

pinctrl-names = “default”;

pinctrl-0 = <&diyblights>;

status = “okay”;

};

};

};

};

`

3

Hi Charles!

Drop all that device tree stuff. Instead use the elegant way for pinmuxing: libpruio. Side effects: faster booting time, smaller memory footprint.

Find example code for pinmuxing, downloading and running PRU firmware at

http://users.freebasic-portal.de/tjf/Projekte/libpruio/doc/html/pruss__toggle_8c_source.html

In your case the following code will do the trick (note: single source, pinmuxing in your program code)

`
if (io->setPin(io, P8_12, 6)) {
printf(“P8_12 configuration failed (%s)\n”, io->Errr); break;}

`if (io->setPin(io, P8_46, 5)) {
printf(“P8_46 configuration failed (%s)\n”, io->Errr); break;}

Regards