//! 使用 `esp-hal` 在 ESP32 上运行 Rust 的示例（裸机 / no_std 模式）
//! 闪烁 LED 并通过 UART 串口发送消息，同时提供内存安全保障。
//!
//! Cargo.toml:
//!   esp-hal = { version = "0.22", features = ["esp32s3"] }
//!   esp-println = { version = "0.12", features = ["esp32s3", "log"] }

#![no_std]
#![no_main]

use esp_backtrace as _;
use esp_hal::{
    clock::ClockControl,
    gpio::{Io, Level, Output},
    peripherals::Peripherals,
    system::SystemControl,
    timer::timg::TimerGroup,
    delay::Delay,
    prelude::*,
};
use esp_println::println;

#[entry]
fn main() -> ! {
    // 在编译期检查的前提下初始化 SoC 外设
    let peripherals = Peripherals::take();
    let system = SystemControl::new(peripherals.SYSTEM);
    let clocks = ClockControl::boot_defaults(system.clock_control).freeze();

    // 配置 I/O 引脚
    let io = Io::new(peripherals.GPIO, peripherals.IO_MUX);
    let mut led = Output::new(io.pins.gpio2, Level::Low);

    let delay = Delay::new(&clocks);

    println!("🦀 Rust bare-metal firmware initialized on ESP32!");

    let mut counter: u32 = 0;

    loop {
        // 在保证互斥的前提下翻转 LED 状态
        led.toggle();
        counter += 1;

        println!("Rust cycle #{}: LED is {:?}", counter, led.is_set_high());
        delay.delay_millis(500);
    }
}