software uart is now a library

semestralka_1_final_crate/software_uart/.cargo/config.toml

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+[build]
+target = "thumbv8m.main-none-eabihf"

semestralka_1_final_crate/software_uart/Cargo.toml

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+[package]
+name = "software_uart"
+version = "1.0.0"
+edition = "2024"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+cortex-m = { version = "0.7.7", features = ["inline-asm", "critical-section-single-core"] }
+cortex-m-rt = "0.7.5"
+panic-halt = "1.0.0"
+embassy-executor = { path = "/home/priec/programs/embassy/embassy-executor", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = { path = "/home/priec/programs/embassy/embassy-futures" }
+embassy-sync = { path = "/home/priec/programs/embassy/embassy-sync" }
+embassy-time = { path = "/home/priec/programs/embassy/embassy-time", features = ["tick-hz-32_768"] }
+embassy-hal-internal = { path = "/home/priec/programs/embassy/embassy-hal-internal" }
+embassy-usb = { path = "/home/priec/programs/embassy/embassy-usb" }
+embassy-stm32 = { path = "/home/priec/programs/embassy/embassy-stm32", features = ["unstable-pac", "stm32u575zi", "time-driver-tim2", "memory-x", "defmt"] }
+
+embedded-hal = "1.0.0"
+embedded-graphics = "0.8.1"
+heapless = { version = "0.9.1", default-features = false }
+micromath = "2.1.0"
+tinybmp = "0.6.0"
+panic-probe = { version = "1.0.0", features = ["defmt"] }
+defmt-rtt = "1.1.0"
+defmt = "1.0.1"
+static_cell = "2.1.1"
+embedded-io = "0.6.1"
+embedded-io-async = "0.6.1"
+
+[dev-dependencies]
+defmt-test = "0.4.0"
+
+[profile.dev]
+opt-level = 3
+codegen-units = 1

semestralka_1_final_crate/software_uart/src/debug.rs

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+// src/debug.rs
+use defmt::info;
+
+pub fn dump_tim6_regs() {
+    use embassy_stm32::pac::timer::TimBasic;
+    let tim = unsafe { TimBasic::from_ptr(0x4000_1000usize as _) };
+    let sr = tim.sr().read();
+    let dier = tim.dier().read();
+    let cr1 = tim.cr1().read();
+    let arr = tim.arr().read().arr();
+    let psc = tim.psc().read();
+    info!(
+        "TIM6: CR1.CEN={} DIER.UDE={} SR.UIF={} PSC={} ARR={}",
+        cr1.cen(),
+        dier.ude(),
+        sr.uif(),
+        psc,
+        arr
+    );
+}
+
+pub fn dump_dma_ch0_regs() {
+    use embassy_stm32::pac::gpdma::Gpdma;
+    let dma = unsafe { Gpdma::from_ptr(0x4002_0000usize as _) };
+    let ch = dma.ch(0);
+    let cr = ch.cr().read();
+    let tr1 = ch.tr1().read();
+    let tr2 = ch.tr2().read();
+    let br1 = ch.br1().read();
+    info!(
+        "GPDMA1_CH0: EN={} PRIO={} SDW={} DDW={} SINC={} DINC={} REQSEL={} SWREQ={} DREQ={} BNDT={}",
+        cr.en(),
+        cr.prio(),
+        tr1.sdw(),
+        tr1.ddw(),
+        tr1.sinc(),
+        tr1.dinc(),
+        tr2.reqsel(),
+        tr2.swreq(),
+        tr2.dreq(),
+        br1.bndt()
+    );
+}

semestralka_1_final_crate/software_uart/src/dma_timer.rs

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+// src/dma_timer.rs
+
+use embassy_stm32::{
+    peripherals::{TIM6, TIM7},
+    rcc,
+    timer::low_level::Timer,
+    Peri,
+};
+use core::mem;
+use embassy_stm32::timer::BasicInstance;
+use embassy_stm32::pac::timer::vals::Urs;
+
+/// Initializes TIM6 to tick at `baud * oversample` frequency.
+/// Each TIM6 update event triggers one DMA beat.
+pub fn init_tim6_for_uart<'d>(tim6: Peri<'d, TIM6>, baud: u32, oversample: u16) {
+    rcc::enable_and_reset::<TIM6>();
+    let ll = Timer::new(tim6);
+    configure_basic_timer(&ll, baud, oversample);
+    mem::forget(ll);
+}
+
+/// Initializes TIM7 to tick at `baud * oversample` frequency.
+/// Each TIM7 update event triggers one DMA beat.
+pub fn init_tim7_for_uart<'d>(tim7: Peri<'d, TIM7>, baud: u32, oversample: u16) {
+    rcc::enable_and_reset::<TIM7>();
+    let ll = Timer::new(tim7);
+    configure_basic_timer(&ll, baud, oversample);
+    // Enable Update Interrupt (UIE)
+    ll.regs_basic().dier().modify(|w| {
+        w.set_ude(true);
+        w.set_uie(false);
+    });
+    mem::forget(ll);
+}
+
+// Shared internal helper — identical CR1/ARR setup
+fn configure_basic_timer<T: BasicInstance>(ll: &Timer<'_, T>, baud: u32, oversample: u16) {
+    let f_timer = rcc::frequency::<T>().0;
+    let target = baud.saturating_mul(oversample.max(1) as u32).max(1);
+
+    // Compute ARR (prescaler = 0)
+    // let mut arr = (f_timer / target).saturating_sub(1) as u16;
+    let mut arr = ((f_timer + target / 2) / target).saturating_sub(1) as u16;
+    if arr == 0 { arr = 1; }
+
+    ll.regs_basic().cr1().write(|w| {
+        w.set_cen(false);
+        w.set_opm(false);
+        w.set_udis(false);
+        w.set_urs(Urs::ANY_EVENT);
+    });
+
+    ll.regs_basic().psc().write_value(0u16);
+    ll.regs_basic().arr().write(|w| w.set_arr(arr));
+    ll.regs_basic().dier().modify(|w| w.set_ude(true));
+    ll.regs_basic().egr().write(|w| w.set_ug(true));
+
+    // Clear spurious UIF from UG trigger
+    ll.regs_basic().sr().modify(|w| w.set_uif(false));
+
+    ll.regs_basic().cr1().write(|w| {
+        w.set_opm(false);
+        w.set_cen(true);
+        w.set_udis(false);
+        w.set_urs(Urs::ANY_EVENT);
+    });
+}

semestralka_1_final_crate/software_uart/src/gpio_dma_uart_rx.rs

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+// src/runtime.rs
+use embassy_executor::task;
+use embassy_stm32::{
+    dma::Request,
+    peripherals::GPDMA1_CH1,
+    Peri,
+};
+use crate::config::RX_PIN_BIT;
+use embassy_stm32::dma::{
+    ReadableRingBuffer,
+    TransferOptions,
+};
+use crate::config::{RX_OVERSAMPLE, UART_CFG};
+use crate::decode_uart_samples;
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+use embassy_futures::yield_now;
+use defmt::info;
+
+// datasheet tabulka 137
+pub const TIM7_UP_REQ: Request = 5;
+
+/// RX DMA task: reads GPIO samples paced by TIM7 and fills PIPE_RX
+#[task]
+pub async fn rx_dma_task(
+    ch: Peri<'static, GPDMA1_CH1>,
+    register: *mut u8,
+    ring: &'static mut [u8],
+    pipe_rx: &'static Pipe<CriticalSectionRawMutex, 4096>,
+) {
+    let mut opts = TransferOptions::default();
+    opts.half_transfer_ir = true;
+    opts.complete_transfer_ir = true;
+
+    // SAFETY: ring is exclusive to this task
+    let mut rx = unsafe { ReadableRingBuffer::new(ch, TIM7_UP_REQ, register, ring, opts) };
+    rx.start();
+
+    // We read into the second half of a buffer, keeping "leftovers" in the first half.
+    const CHUNK_SIZE: usize = 4096;
+    const HISTORY_SIZE: usize = 512;
+    const TOTAL_BUF_SIZE: usize = HISTORY_SIZE + CHUNK_SIZE;
+    
+    // Logic level buffer
+    let mut level_buf = [0u8; TOTAL_BUF_SIZE];
+    let mut valid_len = 0usize; 
+
+    let mut raw_chunk = [0u8; CHUNK_SIZE];
+
+    loop {
+        let _ = rx.read_exact(&mut raw_chunk).await;
+
+        for (i, b) in raw_chunk.iter().enumerate() {
+             level_buf[valid_len + i] = ((*b >> RX_PIN_BIT) & 1) as u8;
+        }
+        let current_end = valid_len + CHUNK_SIZE;
+
+        let (decoded, consumed) = decode_uart_samples(
+            &level_buf[..current_end], 
+            RX_OVERSAMPLE, 
+            &UART_CFG
+        );
+
+        if !decoded.is_empty() {
+             pipe_rx.write(decoded.as_slice()).await;
+
+             for byte in decoded.as_slice() {
+                 // info!("DMA BUFFER CHAR: {} (ASCII: {})", *byte, *byte as char);
+             }
+        }
+
+        // Shift remaining data to front
+        // We processed 'consumed' samples.
+        // We keep everything from 'consumed' up to 'current_end'.
+        let remaining = current_end - consumed;
+        
+        // SAFETY if remaining > HISTORY_SIZE, we are in trouble (buffer too small / decoder stuck).
+        if remaining > 0 {
+            level_buf.copy_within(consumed..current_end, 0);
+        }
+        valid_len = remaining;
+        
+        // If valid_len grows too large (decoder not consuming), we must discard to avoid panic on next write
+        if valid_len >= HISTORY_SIZE {
+             // Discard oldest to make space
+             // logic: we move the last (HISTORY_SIZE/2) to 0.
+             // This effectively "skips" garbage data.
+             let keep = HISTORY_SIZE / 2;
+             level_buf.copy_within(valid_len - keep..valid_len, 0);
+             valid_len = keep;
+        }
+
+        yield_now().await;
+    }
+}

semestralka_1_final_crate/software_uart/src/gpio_dma_uart_tx.rs

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+// src/gpio_dma_uart_tx.rs
+use embassy_executor::task;
+use embassy_stm32::{
+    dma::{Request, Transfer, TransferOptions},
+    peripherals::GPDMA1_CH0,
+    Peri,
+};
+use embassy_futures::yield_now;
+use defmt::info;
+
+use crate::UartConfig;
+use embassy_sync::pipe::Pipe;
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use crate::uart_emulation::encode_uart_byte_cfg;
+
+pub const TIM6_UP_REQ: Request = 4;
+
+pub async fn encode_uart_frames<'a>(
+    pin_bit: u8,
+    bytes: &[u8],
+    out_buf: &'a mut [u32],
+    uart_cfg: &UartConfig,
+) -> usize {
+    let mut offset = 0;
+    for &b in bytes {
+        let mut frame = [0u32; 12];
+        let used = encode_uart_byte_cfg(pin_bit, b, uart_cfg, &mut frame);
+
+        if offset + used <= out_buf.len() {
+            out_buf[offset..offset + used].copy_from_slice(&frame[..used]);
+            offset += used;
+        } else {
+            break;
+        }
+
+        yield_now().await;
+    }
+    offset
+}
+
+#[task]
+pub async fn tx_dma_task(
+    mut ch: Peri<'static, GPDMA1_CH0>,
+    register: *mut u32, // GPIOx_BSRR
+    _tx_ring_mem: &'static mut [u32],
+    pipe_rx: &'static Pipe<CriticalSectionRawMutex, 1024>,
+    tx_pin_bit: u8,
+    uart_cfg: &'static UartConfig,
+) {
+    info!("TX DMA task ready (One‑shot)");
+
+    let mut frame_buf = [0u32; 4096];
+    let mut rx_buf = [0u8; 256];
+    let tim6 = embassy_stm32::pac::TIM6;
+
+    loop {
+        let n = pipe_rx.read(&mut rx_buf).await;
+        if n == 0 {
+            yield_now().await;
+            continue;
+        }
+
+        let used = encode_uart_frames(tx_pin_bit, &rx_buf[..n], &mut frame_buf, uart_cfg).await;
+        if used > 0 {
+            // Clear pending UIF
+            tim6.sr().write(|w| w.set_uif(false));
+            // Wait for the next UIF (next bit tick)
+            while !tim6.sr().read().uif() {
+                yield_now().await;
+            }
+            // Clear UIF so first DMA beat happens on the FOLLOWING tick
+            tim6.sr().write(|w| w.set_uif(false));
+
+            let mut tx_opts = TransferOptions::default();
+            tx_opts.half_transfer_ir = false;
+            tx_opts.complete_transfer_ir = true;
+
+            unsafe {
+                let transfer = Transfer::new_write(
+                    ch.reborrow(),
+                    TIM6_UP_REQ,
+                    &frame_buf[..used],
+                    register,
+                    tx_opts,
+                );
+                transfer.await;
+            }
+        }
+
+        // info!("tx_dma_task sent {} words", used);
+        yield_now().await;
+    }
+}

semestralka_1_final_crate/software_uart/src/lib.rs

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+// src/lib.rs
+
+#![no_std]
+
+pub mod gpio_dma_uart_tx;
+pub mod gpio_dma_uart_rx;
+pub mod dma_timer;
+pub mod uart_emulation;
+pub mod debug;
+
+pub use gpio_dma_uart_tx::*;
+pub use gpio_dma_uart_rx::*;
+pub use dma_timer::*;
+pub use uart_emulation::*;
+pub use debug::*;

semestralka_1_final_crate/software_uart/src/uart_emulation.rs

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+// src/uart_emulation.rs
+use heapless::Vec;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum Parity {
+    None,
+    Even,
+    Odd,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum StopBits {
+    One,
+    Two,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct UartConfig {
+    pub data_bits: u8,
+    pub parity: Parity,
+    pub stop_bits: StopBits,
+}
+
+impl Default for UartConfig {
+    fn default() -> Self {
+        Self {
+            data_bits: 8,
+            parity: Parity::None,
+            stop_bits: StopBits::One,
+        }
+    }
+}
+
+/// Encodes one byte into a sequence of GPIO BSRR words
+pub fn encode_uart_byte_cfg(
+    pin_bit: u8,
+    data: u8,
+    cfg: &UartConfig,
+    out: &mut [u32; 12],
+) -> usize {
+    // GPIOx_BSRR register str. 636 kap. 13.4.7
+    let set_high = |bit: u8| -> u32 { 1u32 << bit };
+    // let set_low = |bit: u8| -> u32 { 0 }; // ODR
+    let set_low = |bit: u8| -> u32 { 1u32 << (bit as u32 + 16) }; // BSRR
+
+    let mut idx = 0usize;
+
+    // START bit (LOW)
+    out[idx] = set_low(pin_bit);
+    idx += 1;
+
+    // Data bits, LSB-first
+    let nbits = cfg.data_bits.clamp(5, 8);
+    for i in 0..nbits {
+        let one = ((data >> i) & 1) != 0;
+        out[idx] = if one { set_high(pin_bit) } else { set_low(pin_bit) };
+        idx += 1;
+    }
+
+    // Parity
+    match cfg.parity {
+        Parity::None => {}
+        Parity::Even | Parity::Odd => {
+            let mask: u8 = if nbits == 8 { 0xFF } else { (1u16 << nbits) as u8 - 1 };
+            let ones = (data & mask).count_ones() & 1;
+            let par_bit_is_one = match cfg.parity {
+                Parity::Even => ones == 1,
+                Parity::Odd => ones == 0,
+                _ => false,
+            };
+            out[idx] = if par_bit_is_one {
+                set_high(pin_bit)
+            } else {
+                set_low(pin_bit)
+            };
+            idx += 1;
+        }
+    }
+
+    // STOP bits (HIGH)
+    let stop_ticks = match cfg.stop_bits {
+        StopBits::One => 1usize,
+        StopBits::Two => 2usize,
+    };
+    for _ in 0..stop_ticks {
+        out[idx] = set_high(pin_bit);
+        idx += 1;
+    }
+
+    idx
+}
+
+/// Decode an oversampled stream of logic levels into UART bytes.
+/// Returns (decoded bytes, number of samples consumed/processed).
+pub fn decode_uart_samples(
+    samples: &[u8],
+    oversample: u16,
+    cfg: &UartConfig,
+) -> (heapless::Vec<u8, 256>, usize) {
+    let mut out = Vec::<u8, 256>::new();
+    let mut idx = 0usize;
+    let nbits = cfg.data_bits as usize;
+    let ovs = oversample as usize;
+
+    // Calculate total frame width in samples to ensure we have enough data
+    // 1 start + n data + parity? + stops
+    let parity_bits = match cfg.parity {
+        Parity::None => 0,
+        _ => 1,
+    };
+    let stop_bits_count = match cfg.stop_bits {
+        StopBits::One => 1,
+        StopBits::Two => 2,
+    };
+    let frame_bits = 1 + nbits + parity_bits + stop_bits_count;
+    let frame_len = frame_bits * ovs;
+
+    // Majority vote over 3 samples centered at `i`
+    let get_bit = |i: usize| -> u8 {
+        let mut votes = 0;
+        // Check i-1, i, i+1. Saturating sub/add handles boundaries roughly.
+        if i > 0 && samples.get(i - 1).map_or(true, |&x| x != 0) {
+            votes += 1;
+        }
+        if samples.get(i).map_or(true, |&x| x != 0) {
+            votes += 1;
+        }
+        if samples.get(i + 1).map_or(true, |&x| x != 0) {
+            votes += 1;
+        }
+
+        if votes >= 2 {
+            1
+        } else {
+            0
+        }
+    };
+
+    // Loop while we have enough remaining samples for a full frame
+    while idx + frame_len <= samples.len() {
+        // Wait for falling edge (High -> Low)
+        // samples[idx] == 1 (Idle/Stop) && samples[idx+1] == 0 (Start)
+        if samples[idx] != 0 && samples[idx + 1] == 0 {
+            // Align to center of START bit
+            // Start bit begins at idx+1. Center is at idx + 1 + (ovs/2)
+            let center_offset = 1 + (ovs / 2);
+            let mut scan_idx = idx + center_offset;
+
+            // Validate Start Bit
+            if get_bit(scan_idx) != 0 {
+                idx += 1; // False start (noise), move on
+                continue;
+            }
+
+            // Move to center of first data bit
+            scan_idx += ovs;
+
+            // Read Data Bits
+            let mut data: u8 = 0;
+            for bit in 0..nbits {
+                if get_bit(scan_idx) == 1 {
+                    data |= 1 << bit;
+                }
+                scan_idx += ovs;
+            }
+
+            // Skip Parity
+            if cfg.parity != Parity::None {
+                scan_idx += ovs;
+            }
+
+            // Validate Stop Bit (Must be 1)
+            // If stop bit is 0, it's a framing error. We reject the whole byte.
+            if get_bit(scan_idx) == 0 {
+                idx += 1; // Next sample
+                continue;
+            }
+
+            // Byte is valid
+            let _ = out.push(data);
+
+            // Active Resync: Fast-forward through the stop bit(s) and idle time
+            // scan_idx is currently at the center of the Stop bit.
+            idx = scan_idx;
+            // Advance while we are reading High (1).
+            // As soon as we see Low (0), we stop. That 0 is the beginning of the NEXT start bit.
+            // The outer loop expects `idx` to be the High *before* the start bit, so we will handle that.
+            while idx < samples.len() && samples[idx] != 0 {
+                idx += 1;
+            }
+            // Back up one step.
+            // The outer loop logic is: `if samples[idx] != 0 && samples[idx+1] == 0`.
+            // If we stopped at `idx` because it was 0, then `idx-1` was the last 1 (Idle).
+            if idx > 0 {
+                idx -= 1;
+            }
+        } else {
+            // No start bit detected here, move to next sample
+            idx += 1;
+        }
+    }
+
+    (out, idx)
+}