BBB boots with pins in mode 5 (pru_out) with 3.3V instead of 0V

[Fabio Luis Girardi]

Hi!

Sorry for the newbie question. I'm building a program to control pins P8.39 to P8.46 of a Beaglebone Black. Everything is ok, except the fact that when I unplug then plug again the power source on the board, these pins starts with 3.3V, that to me (and to the solution that I'm trying to develop) is a really big problem.

I'm only writing here because all examples that I found use mode 7 (GPIO). Nothing showing how to do that with mode 5 (PRU_OUT)

Here is the DTS file that I make to set up the pins to be used from PRU1

/*

 * This is a template-generated file from BoneScript

 */

/dts-v1/;

/plugin/;

/{

    compatible = "ti,beaglebone", "ti,beaglebone-black";

    part_number = "PRU1_FAST_GPIOs";

    exclusive-use =

        "P8.27",

        "P8.28",

        "P8.29",

        "P8.39",

        "P8.40",

        "P8.41",

        "P8.42",

        "P8.43",

        "P8.44",

        "P8.45",

        "P8.46",

        "P9.39",    // AIN0

        "P9.40",    // AIN1

        "P9.37",    // AIN2

        "P9.38",    // AIN3

        "P9.33",    // AIN4

        "P9.36",    // AIN5

        "P9.35",    // AIN6       

        "pr1_pru1_pru_r31",

        "pr1_pru1_pru_r30",

        "tscadc"; // hardware ip used

    fragment@0 {

        target = <&am33xx_pinmux>;

        __overlay__ {

            bs_pinmode_PRU1_GPIOS: pinmux_bs_pru1_outputs {

                pinctrl-single,pins = <0x0e0 0x26

                                       0x0e8 0x26

                                       0x0e4 0x26

                                       0x0b8 0x05

                                       0x0bc 0x05

                                       0x0b0 0x05

                                       0x0b4 0x05

                                       0x0a8 0x05

                                       0x0ac 0x05

                                       0x0a0 0x05

                                       0x0a4 0x05

                                      >;

            };

        };

    };

    fragment@1 {

        target = <&ocp>;

        __overlay__ {

            bs_pinmode_P8_PR1_pinmux {

                compatible = "bone-pinmux-helper";

                status = "okay";

                pinctrl-names = "default";

                pinctrl-0 = <&bs_pinmode_PRU1_GPIOS>;

            };

        };

    };

  fragment@2 {

    target = <&tscadc>;

    __overlay__ {

      status = "okay";

      adc {

        ti,adc-channels = <0 1 2 3 4 5 6 7>;

        ti,chan-step-avg = <16 16 16 16 16 16 16 16>;

        ti,chan-step-opendelay = <0x98 0x98 0x98 0x98 0x98 0x98 0x98 0x98>;

        ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0 0x0>;

      };

    };

  };   

};

[Robert Nelson]

On Fri, Jul 17, 2020 at 12:13 PM Fabio Luis Girardi
<papelhi...@gmail.com> wrote:
>
> Hi!
>
> Sorry for the newbie question. I'm building a program to control pins P8.39 to P8.46 of a Beaglebone Black. Everything is ok, except the fact that when I unplug then plug again the power source on the board, these pins starts with 3.3V, that to me (and to the solution that I'm trying to develop) is a really big problem.

Some pins have odd startup states, just wire up a 74 logic inverter to
the pin to change the output on power-on..

Regards,

--
Robert Nelson
https://rcn-ee.com/