metronome/rust/pm-kit/src/main.rs

//! PM_K-1 firmware — Stage 3 bring-up.
//! Milestone 1 (done): blink GP25 → proved boot/flash.
//! Milestone 2 (this): init the ST7796 320×480 display over SPI0 and draw to it.
//! Pins (from the CircuitPython firmware): SCK=GP2, MOSI=GP3, CS=GP5, DC=GP6, RST=GP7;
//! BGR panel, colours inverted. LED on GP25 keeps blinking as a heartbeat.

#![no_std]
#![no_main]

extern crate alloc;
use alloc::vec::Vec;
use embedded_alloc::LlffHeap as Heap;

#[global_allocator]
static HEAP: Heap = Heap::empty();

use embedded_hal::delay::DelayNs;
use embedded_hal::digital::{InputPin, OutputPin};
use embedded_hal::pwm::SetDutyCycle;
use embedded_hal_0_2::adc::OneShot;
use embedded_hal_bus::spi::ExclusiveDevice;
use mipidsi::interface::{Interface, SpiInterface};
use mipidsi::models::ST7796;
use mipidsi::options::{ColorInversion, ColorOrder, Orientation};
use mipidsi::Builder;
use panic_halt as _;
use rp235x_hal as hal;
use hal::fugit::RateExtU32;
use hal::Clock;

/// Image definition block — the RP2350 bootrom looks for this to boot the image.
#[link_section = ".start_block"]
#[used]
pub static IMAGE_DEF: hal::block::ImageDef = hal::block::ImageDef::secure_exe();

const XTAL_FREQ_HZ: u32 = 12_000_000;
const WIDTH: u16 = 320;
const HEIGHT: u16 = 480;

/// No-op chip-select for the SPI wrapper. The real CS (GP5) is held low for the whole session,
/// because mipidsi's SpiInterface sends a command and its parameters as SEPARATE SpiDevice
/// transactions — a normal SpiDevice would toggle CS between them, and the ST7796 needs CS
/// continuous across command+parameters (so MADCTL/COLMOD/B6 args load). DC selects cmd vs data.
struct NoCs;
impl embedded_hal::digital::ErrorType for NoCs {
    type Error = core::convert::Infallible;
}
impl OutputPin for NoCs {
    fn set_low(&mut self) -> Result<(), core::convert::Infallible> {
        Ok(())
    }
    fn set_high(&mut self) -> Result<(), core::convert::Infallible> {
        Ok(())
    }
}

#[hal::entry]
fn main() -> ! {
    // heap for track parsing (track-format uses alloc). RP2350 has 520 KB SRAM.
    {
        use core::mem::MaybeUninit;
        const HEAP_SIZE: usize = 16 * 1024;
        static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
        unsafe { HEAP.init(core::ptr::addr_of_mut!(HEAP_MEM) as usize, HEAP_SIZE) }
    }

    let mut pac = hal::pac::Peripherals::take().unwrap();
    let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
    let clocks = hal::clocks::init_clocks_and_plls(
        XTAL_FREQ_HZ,
        pac.XOSC,
        pac.CLOCKS,
        pac.PLL_SYS,
        pac.PLL_USB,
        &mut pac.RESETS,
        &mut watchdog,
    )
    .ok()
    .unwrap();

    let mut timer = hal::Timer::new_timer0(pac.TIMER0, &mut pac.RESETS, &clocks);
    let sio = hal::Sio::new(pac.SIO);
    let pins = hal::gpio::Pins::new(pac.IO_BANK0, pac.PADS_BANK0, sio.gpio_bank0, &mut pac.RESETS);

    let mut led = pins.gpio25.into_push_pull_output();
    led.set_high().unwrap(); // solid ON during init: if it stays solid → hung in init; slow blink → reached the loop

    // --- ST7796 over SPI0 ---
    let sclk = pins.gpio2.into_function::<hal::gpio::FunctionSpi>();
    let mosi = pins.gpio3.into_function::<hal::gpio::FunctionSpi>();
    let dc = pins.gpio6.into_push_pull_output();
    let mut rst = pins.gpio7.into_push_pull_output();
    let mut cs = pins.gpio5.into_push_pull_output();
    cs.set_low().unwrap(); // hold CS low for the whole session (see NoCs) — the fix for the 1/4 panel

    let spi = hal::spi::Spi::<_, _, _, 8>::new(pac.SPI0, (mosi, sclk));
    let spi = spi.init(
        &mut pac.RESETS,
        clocks.peripheral_clock.freq(),
        16.MHz(),
        embedded_hal::spi::MODE_0,
    );
    let spi_device = ExclusiveDevice::new_no_delay(spi, NoCs).unwrap();

    let mut buffer = [0u8; 512];
    let mut di = SpiInterface::new(spi_device, dc, &mut buffer);

    // Hardware reset, then the FULL known-good CircuitPython st7796_init as the PRIMARY bring-up
    // (right after reset, the only time the panel accepts the extension setup cleanly). Confirmed
    // necessary: mipidsi's address window + MADCTL already match CircuitPython (host initdump), so
    // the only remaining difference was this extension init not running as the primary init.
    rst.set_high().unwrap();
    timer.delay_ms(5);
    rst.set_low().unwrap();
    timer.delay_ms(20);
    rst.set_high().unwrap();
    timer.delay_ms(150);

    di.send_command(0x01, &[]).unwrap(); // SWRESET
    timer.delay_ms(120);
    di.send_command(0x11, &[]).unwrap(); // SLPOUT
    timer.delay_ms(120);
    di.send_command(0xF0, &[0xC3]).unwrap(); // unlock extension command set
    di.send_command(0xF0, &[0x96]).unwrap();
    di.send_command(0x36, &[0x48]).unwrap(); // MADCTL
    di.send_command(0x3A, &[0x55]).unwrap(); // COLMOD 16bpp
    di.send_command(0xB4, &[0x01]).unwrap();
    di.send_command(0xB6, &[0x80, 0x02, 0x3B]).unwrap(); // display function control: 480 lines
    di.send_command(0xE8, &[0x40, 0x8A, 0x00, 0x00, 0x29, 0x19, 0xA5, 0x33]).unwrap();
    di.send_command(0xC1, &[0x06]).unwrap();
    di.send_command(0xC2, &[0xA7]).unwrap();
    di.send_command(0xC5, &[0x18]).unwrap();
    timer.delay_ms(120);
    di.send_command(0xE0, &[0xF0, 0x09, 0x0B, 0x06, 0x04, 0x15, 0x2F, 0x54, 0x42, 0x3C, 0x17, 0x14, 0x18, 0x1B]).unwrap();
    di.send_command(0xE1, &[0xE0, 0x09, 0x0B, 0x06, 0x04, 0x03, 0x2B, 0x43, 0x42, 0x3B, 0x16, 0x14, 0x17, 0x1B]).unwrap();
    di.send_command(0xF0, &[0x3C]).unwrap(); // lock
    di.send_command(0xF0, &[0x69]).unwrap();
    timer.delay_ms(120);
    di.send_command(0x21, &[]).unwrap(); // INVON (INVERT_COLORS = true)
    di.send_command(0x29, &[]).unwrap(); // DISPON
    timer.delay_ms(50);

    // Build mipidsi for DRAWING only — NO reset_pin (already reset), so it just re-asserts the
    // basics (SLPOUT/MADCTL=0x48/INVON/COLMOD/NORON/DISPON) without touching the extension setup.
    let mut display = Builder::new(ST7796, di)
        .display_size(WIDTH, HEIGHT)
        .color_order(ColorOrder::Bgr)
        .invert_colors(ColorInversion::Inverted)
        .orientation(Orientation::new().flip_horizontal())
        .init(&mut timer)
        .unwrap();

    // ---- MINIMAL ISOLATION ----
    // Heap is initialised above. Exercise the allocator once (parse), then just draw the
    // confirmed-working pattern in a loop. No inputs/audio/clock. If the screen shows blue +
    // corners → heap + parse + display are all fine and the bug is in the metronome loop logic.
    // If still black → the heap/parse path breaks the display.
    // (parse removed for this test — heap init only)
    let mut hb = false;
    let mut hb_us = 0u64;
    led.set_low().unwrap();
    loop {
        pm_ui::draw_ui(&mut display).ok();
        let now = timer.get_counter().ticks();
        if now.wrapping_sub(hb_us) > 500_000 {
            hb = !hb;
            let _ = if hb { led.set_high() } else { led.set_low() };
            hb_us = now;
        }
        timer.delay_ms(50);
    }
}