#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]
#![feature(impl_trait_in_assoc_type)]

// Simple 555-like oscillator implemented in firmware.
// - Q output: PB2 (also drives the on-board LED if present)
// - Combined Trigger/Threshold analog input: PA0 (capacitor node)
// Wiring suggestion:
//   Q (PB2) --[R]--+-- C -- GND
//                   |
//                 PA0 (ADC input)
// The firmware toggles Q high when PA0 <= 1/3 Vref and low when PA0 >= 2/3 Vref.

use embassy_executor::Spawner;
use embassy_time::Timer;
use hal::gpio::{Level, Output};
use {ch32_hal as hal, panic_halt as _};

use hal::adc::{Adc, SampleTime};

#[embassy_executor::main(entry = "qingke_rt::entry")]
async fn main(_spawner: Spawner) -> ! {
    let p = hal::init(Default::default());

    // Q output on PB2
    let mut q = Output::new(p.PB2, Level::Low, Default::default());

    // ADC on PA0 for combined Trigger/Threshold input
    let mut adc = Adc::new(p.ADC1, Default::default());
    let mut trig_thres = p.PA0; // analog-capable pin used as ADC channel

    // ADC characteristics: assume 12-bit if HAL doesn't expose it.
    // If the HAL provides a method to query resolution, prefer that.
    let full_scale: u16 = 4095; // 12-bit default
    let thr_low: u16 = (full_scale as u32 / 3) as u16;        // ~1/3 Vref
    let thr_high: u16 = ((full_scale as u32 * 2) / 3) as u16; // ~2/3 Vref

    // Start with Q low. State variable to avoid redundant toggles.
    let mut q_high = false;
    q.set_low();

    loop {
        // Read capacitor node voltage via ADC
        let sample: u16 = adc.convert(&mut trig_thres, SampleTime::CYCLES239_5);

        // Implement Schmitt trigger behavior like NE555 using thresholds
        if !q_high && sample <= thr_low {
            // Trigger: voltage fell below 1/3 Vref -> set output high
            q.set_high();
            q_high = true;
        } else if q_high && sample >= thr_high {
            // Threshold: voltage rose above 2/3 Vref -> set output low
            q.set_low();
            q_high = false;
        }

        // Small delay to reduce CPU usage; adjust for responsiveness/noise
        Timer::after_micros(200).await;
    }
}