BEAGL-BONE-BLACK: Pulldown on GPIO Pinmux not working

Felix Salcher

Part Number: BEAGL-BONE-BLACK

Tool/software:

HI there,

I'm currently developing a bare metal operating system in rust on the beaglebone as my final highschool project. I successfully booted the controller and also managed to read and write to the GPIO pins.

I then tried to set a pulldown behaviour for the gpio pins through the pinmuxing, which I sucessfully achieved on the pin gpio1_28. But when trying to set the same for the pins gpio1_6 and gpio1_16 which correspond to the pins gpmc_ad6 and gpmc_a0 respectively, they behave the same as before.

I also tried to ask the deepseek ai about this, and it thought that it may be a lock on the pins, which isn't documented but was used by some things, but unfortunately I couldn't find anything regarding to that, so that could also just be false.

Felix

9 months ago

0 Felix Salcher 9 months ago

Prodigy 40 points

const CONTROL_MODULE_BASE: u32 = 0x44E10000;

enum Offset {
    Lock = 0x20C,
    GpmcBen1 = 0x878, // GPIO1_28
    GpmcAd6 = 0x818,  // GPIO1_6
    GpmcA0 = 0x840,   // GPIO1_16
}

pub fn configure() {
    set_pin_mode(Offset::GpmcBen1, 7, true, PullResistor::PullUp);
    set_pin_mode(Offset::GpmcAd6, 7, true, PullResistor::PullDown);
    set_pin_mode(Offset::GpmcA0, 7, true, PullResistor::PullDown);
}

fn set_pin_mode(offset: Offset, mode: u32, input_enable: bool, pull_resistor: PullResistor) {
    write_addr(CONTROL_MODULE_BASE + Offset::Lock as u32, 0xAAAA);
    let control_module = CONTROL_MODULE_BASE + offset as u32;

    write_addr(
        control_module,
        (mode & 7) | pull_resistor.to_mask() | ((input_enable as u32) << 5),
    );
}

pub enum PullResistor {
    None,
    PullDown,
    PullUp,
}

impl PullResistor {
    pub fn to_mask(self) -> u32 {
        match self {
            PullResistor::PullDown => 0b00 << 3,
            PullResistor::PullUp => 0b10 << 3,
            PullResistor::None => 0b01 << 3,
        }
    }
}

This is the code to set the control module. Although it is rust which many won't be too familiar, I hope one can understand the code

0 Krunal Bhargav34 9 months ago in reply to Felix Salcher

TI__Mastermind 44805 points

Hi,

Could you please check with the beagle community: https://www.ourbeagleworld.com/forums/

Regards,
Krunal

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BEAGL-BONE-BLACK: Pulldown on GPIO Pinmux not working