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Blink an LED on pi

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This commit is contained in:
Alexander Neuhäuser
2025-05-19 18:33:13 +02:00
parent d4063f025d
commit 948cbf758f
11 changed files with 44 additions and 62 deletions
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60
src/gpio.rs
View File

@@ -3,66 +3,28 @@ use crate::{
uart::{self},
};
const GPFSEL2: u32 = 0x3F20_0008; //GPIO 20-29
const GPFSEL4: u32 = 0x3F20_0010; //GPIO 40-49
const GPPUD: u32 = 0x3F20_0094;
const GPPUD_CLK: u32 = 0x3F20_0098; // GPIO 32-53
const GPSET0: u32 = 0x3F20_001C;
const GPCLR0: u32 = 0x3F20_0028;
unsafe fn set_gpio47_to_output() {
let value: u32 = 0b001 << 21;
unsafe fn set_gpio29_to_output() {
let value: u32 = 0b001 << 27;
core::ptr::write_volatile(GPFSEL4 as *mut u32, value);
core::ptr::write_volatile(GPFSEL2 as *mut u32, value);
}
unsafe fn enable_pull_up() {
let value: u32 = 0b10;
core::ptr::write_volatile(GPPUD as *mut u32, value);
}
unsafe fn enable_pull_down() {
let value: u32 = 0b01;
core::ptr::write_volatile(GPPUD as *mut u32, value);
}
unsafe fn disable_GPPUD() {
core::ptr::write_volatile(GPPUD as *mut u32, 0);
}
unsafe fn enable_clock_gpio47() {
let value: u32 = 0b1 << 13;
core::ptr::write_volatile(GPPUD as *mut u32, value);
}
unsafe fn disable_GPPUD_CLK() {
core::ptr::write_volatile(GPPUD as *mut u32, 0);
}
pub fn pull_up_gpio47() {
pub fn pull_up_gpio29() {
unsafe {
uart::print("Pull Up\n");
set_gpio47_to_output();
enable_pull_up();
// Wait 150 cycles
delay(150);
enable_clock_gpio47();
delay(150);
disable_GPPUD();
disable_GPPUD_CLK();
set_gpio29_to_output();
core::ptr::write_volatile(GPSET0 as *mut u32, 1 << 29);
}
}
pub fn pull_down_gpio47() {
pub fn pull_down_gpio29() {
unsafe {
uart::print("Pull Down\n");
set_gpio47_to_output();
enable_pull_down();
// Wait 150 cycles
delay(150);
enable_clock_gpio47();
delay(150);
disable_GPPUD();
disable_GPPUD_CLK();
core::ptr::write_volatile(GPCLR0 as *mut u32, 1 << 29);
}
}

22
src/main.rs
View File

@@ -2,9 +2,9 @@
#![no_std]
#![feature(asm_experimental_arch)]
use core::panic::PanicInfo;
use core::{arch::asm, panic::PanicInfo};
use gpio::{pull_down_gpio47, pull_up_gpio47};
use gpio::{pull_down_gpio29, pull_up_gpio29};
mod gpio;
mod uart;
@@ -12,18 +12,20 @@ mod uart;
#[panic_handler]
fn panic(_panic: &PanicInfo) -> ! {
loop {
pull_up_gpio29();
uart::print("Panic");
}
}
#[no_mangle]
#[unsafe(naked)]
pub extern "C" fn _start() -> ! {
core::arch::naked_asm!("mov sp, #0x80000", "bl main");
#[link_section = ".text._start"]
pub unsafe extern "C" fn _start() {
asm!("ldr x0, =0x8004000", "mov sp, x0");
main();
}
#[no_mangle]
fn main() {
extern "C" fn main() {
uart::configure_uart();
// Delay so clock speed can stabilize
@@ -31,10 +33,10 @@ fn main() {
uart::print("Hello World!\n");
loop {
pull_up_gpio47();
unsafe { delay(10_000_000) } // ~0.5s
pull_down_gpio47();
unsafe { delay(10_000_000) }
pull_up_gpio29();
unsafe { delay(1_000_000) }
pull_down_gpio29();
unsafe { delay(1_000_000) }
}
}