compiled and working

.gitignore

@@ -0,0 +1 @@
+*.pdf

datasheet.txt

@@ -0,0 +1 @@
+https://www.st.com/content/ccc/resource/technical/document/reference_manual/group0/f3/60/ca/d2/98/c8/47/88/DM00477635/files/DM00477635.pdf/jcr:content/translations/en.DM00477635.pdf

dma_gpio/.cargo/config.toml

@@ -0,0 +1,15 @@
+[build]
+target = "thumbv8m.main-none-eabihf"
+
+[target.thumbv8m.main-none-eabihf]
+runner = "probe-rs run --chip STM32U575ZITxQ"
+
+rustflags = [
+  "-C", "linker=rust-lld",
+  "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
+  "-C", "link-arg=--nmagic",
+]
+
+[package.metadata.cargo-flash]
+chip = "STM32U575ZIT"

dma_gpio/.gitignore

@@ -0,0 +1 @@
+/target

dma_gpio/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+authors = ["Priec <filippriec@gmail.com>"]
+name = "dma_gpio"
+edition = "2024"
+version = "0.1.0"
+
+
+[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 = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
+embassy-sync    = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
+embassy-time    = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["tick-hz-32_768"] }
+embassy-hal-internal = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
+embassy-usb = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
+embassy-stm32 = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["unstable-pac", "stm32u575zi", "time-driver-any", "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"

dma_gpio/LICENSE-APACHE

@@ -0,0 +1,201 @@
+                              Apache License
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+
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+
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+See the License for the specific language governing permissions and
+limitations under the License.

dma_gpio/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

dma_gpio/Makefile

@@ -0,0 +1,23 @@
+TARGET = thumbv8m.main-none-eabihf
+CHIP = STM32U575ZI
+BIN = stm32u5-blinky
+MODE ?= release
+TARGET_DIR = target/$(TARGET)/$(MODE)
+ELF = $(TARGET_DIR)/$(BIN)
+PROBE = probe-rs
+
+.PHONY: all build flash clean empty
+
+all: build
+
+build:
+	cargo build --$(MODE)
+
+flash: build
+	$(PROBE) run --chip $(CHIP) $(ELF)
+
+empty:
+	$(PROBE) erase --chip $(CHIP)
+
+clean:
+	cargo clean

dma_gpio/README.md

@@ -0,0 +1,232 @@
+# `app-template`
+
+> Quickly set up a [`probe-rs`] + [`defmt`] + [`flip-link`] embedded project
+
+[`probe-rs`]: https://crates.io/crates/probe-rs
+[`defmt`]: https://github.com/knurling-rs/defmt
+[`flip-link`]: https://github.com/knurling-rs/flip-link
+
+## Dependencies
+
+### 1. `flip-link`:
+
+```bash
+cargo install flip-link
+```
+
+### 2. `probe-rs`:
+
+Install probe-rs by following the instructions at <https://probe.rs/docs/getting-started/installation/>.
+
+### 3. [`cargo-generate`]:
+
+```bash
+cargo install cargo-generate
+```
+
+[`cargo-generate`]: https://crates.io/crates/cargo-generate
+
+> *Note:* You can also just clone this repository instead of using `cargo-generate`, but this involves additional manual adjustments.
+
+## Setup
+
+### 1. Initialize the project template
+
+```bash
+cargo generate \
+    --git https://github.com/knurling-rs/app-template \
+    --branch main \
+    --name my-app
+```
+
+If you look into your new `my-app` folder, you'll find that there are a few `TODO`s in the files marking the properties you need to set.
+
+Let's walk through them together now.
+
+### 2. Set `probe-rs` chip
+
+Pick a chip from ` probe-rs chip list` and enter it into `.cargo/config.toml`.
+
+If, for example, you have a nRF52840 Development Kit as used in one of [our exercises], replace `{{chip}}` with `nRF52840_xxAA`.
+
+[our workshops]: https://rust-exercises.ferrous-systems.com
+
+```diff
+ # .cargo/config.toml
+-runner = ["probe-rs", "run", "--chip", "$CHIP", "--log-format=oneline"]
++runner = ["probe-rs", "run", "--chip", "nRF52840_xxAA", "--log-format=oneline"]
+```
+
+### 3. Adjust the compilation target
+
+In `.cargo/config.toml`, pick the right compilation target for your board.
+
+```diff
+ # .cargo/config.toml
+ [build]
+-target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+-# target = "thumbv7m-none-eabi"    # Cortex-M3
+-# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+-# target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
++target = "thumbv7em-none-eabihf" # Cortex-M4F (with FPU)
+```
+
+Add the target with `rustup`.
+
+```bash
+rustup target add thumbv7em-none-eabihf
+```
+
+### 4. Add a HAL as a dependency
+
+In `Cargo.toml`, list the Hardware Abstraction Layer (HAL) for your board as a dependency.
+
+For the nRF52840 you'll want to use the [`nrf52840-hal`].
+
+[`nrf52840-hal`]: https://crates.io/crates/nrf52840-hal
+
+```diff
+ # Cargo.toml
+ [dependencies]
+-# some-hal = "1.2.3"
++nrf52840-hal = "0.14.0"
+```
+
+⚠️ Note for RP2040 users ⚠️
+
+You will need to not just specify the `rp-hal` HAL, but a BSP (board support crate) which includes a second stage bootloader. Please find a list of available BSPs [here](https://github.com/rp-rs/rp-hal-boards#packages).
+
+### 5. Import your HAL
+
+Now that you have selected a HAL, fix the HAL import in `src/lib.rs`
+
+```diff
+ // my-app/src/lib.rs
+-// use some_hal as _; // memory layout
++use nrf52840_hal as _; // memory layout
+```
+
+### (6. Get a linker script)
+
+Some HAL crates require that you manually copy over a file called `memory.x` from the HAL to the root of your project. For nrf52840-hal, this is done automatically so no action is needed. For other HAL crates, see their documentation on where to find an example file.
+
+The `memory.x` file should look something like:
+
+```text
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 1024K
+  RAM   : ORIGIN = 0x20000000, LENGTH = 256K
+}
+```
+
+The `memory.x` file is included in the `cortex-m-rt` linker script `link.x`, and so `link.x` is the one you should tell `rustc` to use (see the `.cargo/config.toml` file where we do that).
+
+### 7. Run!
+
+You are now all set to `cargo-run` your first `defmt`-powered application!
+There are some examples in the `src/bin` directory.
+
+Start by `cargo run`-ning `my-app/src/bin/hello.rs`:
+
+```console
+$ # `rb` is an alias for `run --bin`
+$ cargo rb hello
+    Finished `dev` profile [optimized + debuginfo] target(s) in 0.01s
+     Running `probe-rs run --chip nrf52840_xxaa --log-format=oneline target/thumbv6m-none-eabi/debug/hello`
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.79 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+Hello, world!
+
+$ echo $?
+0
+```
+
+If you're running out of memory (`flip-link` bails with an overflow error), you can decrease the size of the device memory buffer by setting the `DEFMT_RTT_BUFFER_SIZE` environment variable. The default value is 1024 bytes, and powers of two should be used for optimal performance:
+
+```console
+$ DEFMT_RTT_BUFFER_SIZE=64 cargo rb hello
+```
+
+### (8. Set `rust-analyzer.linkedProjects`)
+
+If you are using [rust-analyzer] with VS Code for IDE-like features you can add following configuration to your `.vscode/settings.json` to make it work transparently across workspaces. Find the details of this option in the [RA docs].
+
+```json
+{
+    "rust-analyzer.linkedProjects": [
+        "Cargo.toml",
+        "firmware/Cargo.toml",
+    ]
+}
+```
+
+[RA docs]: https://rust-analyzer.github.io/manual.html#configuration
+[rust-analyzer]: https://rust-analyzer.github.io/
+
+## Running tests
+
+The template comes configured for running unit tests and integration tests on the target.
+
+Unit tests reside in the library crate and can test private API; the initial set of unit tests are in `src/lib.rs`.
+`cargo test --lib` will run those unit tests.
+
+```console
+$ cargo test --lib
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.15s
+     Running unittests src/lib.rs (target/thumbv6m-none-eabi/debug/deps/example-2b0d0e25d141bf57)
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.99 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.33 KiB/s (took 1s)                                                                                                                        Finished in 1.10s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Integration tests reside in the `tests` directory; the initial set of integration tests are in `tests/integration.rs`.
+`cargo test --test integration` will run those integration tests.
+Note that the argument of the `--test` flag must match the name of the test file in the `tests` directory.
+
+```console
+$ cargo test --test integration
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.10s
+     Running tests/integration.rs (target/thumbv6m-none-eabi/debug/deps/integration-aaaff41151f6a722)
+      Erasing ✔ 100% [####################]   8.00 KiB @  16.03 KiB/s (took 0s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Note that to add a new test file to the `tests` directory you also need to add a new `[[test]]` section to `Cargo.toml`.
+
+To run all the tests via `cargo test` the tests need to be explicitly disabled for all the existing binary targets.
+See `Cargo.toml` for details on how to do this.
+
+## Support
+
+`app-template` is part of the [Knurling] project, [Ferrous Systems]' effort at
+improving tooling used to develop for embedded systems.
+
+If you think that our work is useful, consider sponsoring it via [GitHub
+Sponsors].
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+licensed as above, without any additional terms or conditions.
+
+[Knurling]: https://knurling.ferrous-systems.com
+[Ferrous Systems]: https://ferrous-systems.com/
+[GitHub Sponsors]: https://github.com/sponsors/knurling-rs

dma_gpio/src/bin/main.rs

@@ -0,0 +1,61 @@
+// src/bin/main.rs
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Input, Output, Level, Pull, Speed};
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+use embassy_time::{Duration, Timer};
+use dma_gpio::software_uart::{
+    dma_timer::{init_tim6_for_uart, init_tim7_for_uart},
+    gpio_dma_uart_tx::{write_uart_frames_to_pipe, UartConfig, Parity, StopBits},
+    runtime::{rx_dma_task, tx_dma_task},
+    debug::dump_tim6_regs,
+};
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+/// SOFTWARE UART CONFIGURATION
+const BAUD: u32 = 115_200;
+const TX_PIN_BIT: u8 = 2; // PA2
+const TX_OVERSAMPLE: u16 = 1;
+const RX_OVERSAMPLE: u16 = 16;
+const PIPE_TX_SIZE: usize = 256;
+const PIPE_RX_SIZE: usize = 256;
+const RX_RING_BYTES: usize = 4096;
+
+static PIPE_TX: Pipe<CriticalSectionRawMutex, PIPE_TX_SIZE> = Pipe::new();
+static PIPE_RX: Pipe<CriticalSectionRawMutex, PIPE_RX_SIZE> = Pipe::new();
+static RX_RING: StaticCell<[u8; RX_RING_BYTES]> = StaticCell::new();
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    info!("Hehe");
+
+    let _rx = Input::new(p.PA3, Pull::Up);
+    let _tx = Output::new(p.PA2, Level::High, Speed::VeryHigh);
+
+    init_tim6_for_uart(p.TIM6, BAUD, TX_OVERSAMPLE);
+    init_tim7_for_uart(p.TIM7, BAUD, RX_OVERSAMPLE);
+    dump_tim6_regs();
+
+    // Safe one-time init from StaticCell
+    let ring: &mut [u8; RX_RING_BYTES] = RX_RING.init([0; RX_RING_BYTES]);
+
+    // Spawn tasks
+    spawner.spawn(tx_dma_task(p.GPDMA1_CH0, &PIPE_TX).unwrap());
+    spawner.spawn(rx_dma_task(p.GPDMA1_CH1, &PIPE_RX, ring).unwrap());
+
+    let uart_cfg = UartConfig {
+        data_bits: 8,
+        parity: Parity::None,
+        stop_bits: StopBits::One,
+    };
+
+    loop {
+        write_uart_frames_to_pipe(&PIPE_TX, TX_PIN_BIT, b"Hello marshmallow\r\n", &uart_cfg).await;
+        Timer::after(Duration::from_secs(2)).await;
+    }
+}

dma_gpio/src/lib.rs

@@ -0,0 +1,3 @@
+#![no_std]
+
+pub mod software_uart;

dma_gpio/src/software_uart/debug.rs

@@ -0,0 +1,43 @@
+// src/software_uart/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()
+    );
+}

dma_gpio/src/software_uart/dma_timer.rs

@@ -0,0 +1,58 @@
+// 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);
+    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;
+    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));
+
+    ll.regs_basic().cr1().write(|w| {
+        w.set_opm(false);
+        w.set_cen(true);
+        w.set_udis(false);
+        w.set_urs(Urs::ANY_EVENT);
+    });
+}

dma_gpio/src/software_uart/gpio_dma_uart_rx.rs

@@ -0,0 +1,57 @@
+// src/gpio_dma_uart_rx.rs
+use embassy_stm32::{
+    dma::{Request, Transfer, TransferOptions},
+    peripherals::GPDMA1_CH1,
+    Peri,
+};
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+
+// RM0456 tabulka 137
+pub const TIM7_UP_REQ: Request = 5;
+
+pub struct GpioDmaRx<'d, const N: usize> {
+    ch: Peri<'d, GPDMA1_CH1>,
+    pin_bit: u8,
+    buf: &'d mut [u32; N],
+    opts: TransferOptions,
+    pipe_rx: &'d Pipe<CriticalSectionRawMutex, 256>,
+}
+
+impl<'d, const N: usize> GpioDmaRx<'d, N> {
+    pub fn new(
+        ch: Peri<'d, GPDMA1_CH1>,
+        pin_bit: u8,
+        buf: &'d mut [u32; N],
+        pipe_rx: &'d Pipe<CriticalSectionRawMutex, 256>,
+    ) -> Self {
+        Self {
+            ch,
+            pin_bit,
+            buf,
+            opts: TransferOptions::default(),
+            pipe_rx,
+        }
+    }
+
+    pub async fn run(&mut self) -> ! {
+        loop {
+            let gpioa_idr_addr = embassy_stm32::pac::GPIOA.as_ptr() as *mut u32;
+
+            unsafe {
+                Transfer::new_read(
+                    self.ch.reborrow(),
+                    TIM7_UP_REQ,
+                    gpioa_idr_addr,
+                    &mut self.buf[..],
+                    self.opts,
+                )
+            }
+            .await;
+
+            for &word in self.buf.iter() {
+                let bit_high = ((word >> self.pin_bit) & 1) as u8;
+                self.pipe_rx.write(&[bit_high]).await;
+            }
+        }
+    }
+}

dma_gpio/src/software_uart/gpio_dma_uart_tx.rs

@@ -0,0 +1,168 @@
+// src/gpio_dma_uart.rs
+use embassy_stm32::{
+    dma::{Request, Transfer, TransferOptions},
+    peripherals::GPDMA1_CH0,
+    Peri,
+};
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+
+// kapitola 17.4.11 - 2 casovace pre 2 DMA
+pub const TIM6_UP_REQ: Request = 4; // Table 137: tim6_upd_dma, strana 687 STM32U5xx datasheet
+
+#[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, // 5..=8 bitov strana 16 TI_uart
+    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,
+        }
+    }
+}
+
+pub struct GpioDmaBsrrTx<'d> {
+    ch: Peri<'d, GPDMA1_CH0>,
+    bsrr: *mut u32,
+    opts: TransferOptions,
+}
+
+impl<'d> GpioDmaBsrrTx<'d> {
+    // Constructor. Hides the raw register pointer internally.
+    pub fn new(ch: Peri<'d, GPDMA1_CH0>) -> Self {
+        let bsrr = embassy_stm32::pac::GPIOA.bsrr().as_ptr() as *mut u32;
+        Self {
+            ch,
+            bsrr,
+            opts: TransferOptions::default(),
+        }
+    }
+
+    // Safe API: perform one timer-paced DMA write of a single 32-bit BSRR word.
+    pub async fn write_word(&mut self, word: u32) {
+        let buf = [word];
+        // Safety: bsrr is a valid 32-bit aligned register, buf lives until DMA completes,
+        // request selects TIM6_UP, which paces one beat per update.
+        unsafe {
+            Transfer::new_write(
+                self.ch.reborrow(),
+                TIM6_UP_REQ,
+                &buf,
+                self.bsrr,
+                self.opts,
+            )
+        }
+        .await;
+    }
+}
+
+// Build up to 12 BSRR words for one UART frame on a given GPIO bit.
+// Format: 1 START (low), N data (LSB first), optional PARITY, STOP(1/2 -> here 1 or 2 ticks).
+// BSRR je safe atomic write only shortcut
+pub fn encode_uart_byte_cfg(
+    pin_bit: u8,
+    data: u8,
+    cfg: &UartConfig,
+    out: &mut [u32; 12],
+) -> usize {
+    // Dokumentacia strana 636 13.4.7
+    // set bit - HIGH, reset bit - LOW (BSRR)
+    let set_high = |bit: u8| -> u32 { 1u32 << bit };
+    let set_low = |bit: u8| -> u32 { 1u32 << (bit as u32 + 16) };
+
+    let mut idx = 0usize;
+
+    // START bit (LOW)
+    out[idx] = set_low(pin_bit);
+    idx += 1;
+
+    // Data bits, LSB first (5..=8)
+    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;
+    }
+
+    // Optional parity
+    match cfg.parity {
+        Parity::None => {}
+        Parity::Even | Parity::Odd => {
+            // Count ones
+            let mask: u8 = if nbits == 8 { 0xFF } else { (1u16 << nbits) as u8 - 1 };
+            let ones = (data & mask).count_ones() & 1; // 0=even, 1=odd
+            let par_bit_is_one = match cfg.parity {
+                Parity::Even => ones == 1, // make total ones even
+                Parity::Odd => ones == 0,  // make total ones odd
+                _ => false,
+            };
+            out[idx] = if par_bit_is_one {
+                set_high(pin_bit)
+            } else {
+                set_low(pin_bit)
+            };
+            idx += 1;
+        }
+    }
+
+    // STOP bits (HIGH)
+    //  - STB=0 => 1 stop bit
+    //  - STB=1 => 2 stop bits
+    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
+}
+
+// Push UART frames for a whole byte slice into a Pipe.
+pub async fn write_uart_frames_to_pipe<const N: usize>(
+    pipe: &Pipe<CriticalSectionRawMutex, N>,
+    pin_bit: u8,
+    bytes: &[u8],
+    cfg: &UartConfig,
+) {
+    for &b in bytes {
+        let mut frame = [0u32; 12];
+        let used = encode_uart_byte_cfg(pin_bit, b, cfg, &mut frame);
+        for w in &frame[..used] {
+            pipe.write(&w.to_le_bytes()).await;
+        }
+    }
+}
+
+// Optional: emit a BREAK (line LOW for 'bits' bit-times).
+pub async fn write_break_to_pipe<const N: usize>(
+    pipe: &Pipe<CriticalSectionRawMutex, N>,
+    pin_bit: u8,
+    bits: usize,
+) {
+    let set_low = |bit: u8| -> u32 { 1u32 << (bit as u32 + 16) };
+    let word = set_low(pin_bit);
+    for _ in 0..bits {
+        pipe.write(&word.to_le_bytes()).await;
+    }
+}

dma_gpio/src/software_uart/mod.rs

@@ -0,0 +1,13 @@
+// src/software_uart/mod.rs
+
+pub mod gpio_dma_uart_tx;
+pub mod gpio_dma_uart_rx;
+pub mod dma_timer;
+pub mod runtime;
+pub mod debug;
+
+pub use gpio_dma_uart_tx::*;
+pub use gpio_dma_uart_rx::*;
+pub use dma_timer::*;
+pub use runtime::*;
+pub use debug::*;

dma_gpio/src/software_uart/runtime.rs

@@ -0,0 +1,69 @@
+// src/software_uart/runtime.rs
+use defmt::{info, warn};
+use embassy_executor::task;
+use embassy_stm32::{
+    dma::{ReadableRingBuffer as DmaRingRx, TransferOptions},
+    peripherals::{GPDMA1_CH0, GPDMA1_CH1},
+    Peri,
+};
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+use embassy_time::Duration;
+use crate::software_uart::{
+    gpio_dma_uart_rx::TIM7_UP_REQ,
+    gpio_dma_uart_tx::GpioDmaBsrrTx,
+    debug::{dump_dma_ch0_regs, dump_tim6_regs},
+};
+
+/// 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>,
+    pipe_rx: &'static Pipe<CriticalSectionRawMutex, 256>,
+    ring: &'static mut [u8],
+) {
+    let gpioa_idr = embassy_stm32::pac::GPIOA.idr().as_ptr() as *mut u8;
+
+    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 { DmaRingRx::new(ch, TIM7_UP_REQ, gpioa_idr, ring, opts) };
+    rx.start();
+
+    let mut chunk = [0u8; 256];
+    loop {
+        let _ = rx.read_exact(&mut chunk).await;
+        pipe_rx.write(&chunk).await;
+    }
+}
+
+/// TX DMA task: dequeues prebuilt frames from PIPE_TX and writes to GPIOA.BSRR
+#[task]
+pub async fn tx_dma_task(
+    ch: Peri<'static, GPDMA1_CH0>,
+    pipe_tx: &'static Pipe<CriticalSectionRawMutex, 256>,
+) {
+    let mut tx = GpioDmaBsrrTx::new(ch);
+    info!("DMA TX task started");
+
+    loop {
+        let mut b = [0u8; 4];
+        let n = pipe_tx.read(&mut b).await;
+        if n != 4 {
+            continue;
+        }
+
+        let w = u32::from_le_bytes(b);
+        info!("DMA write 0x{:08X} -> GPIOA.BSRR", w);
+
+        match embassy_time::with_timeout(Duration::from_millis(20), tx.write_word(w)).await {
+            Ok(()) => {}
+            Err(_) => {
+                warn!("DMA timeout: no TIM6 request");
+                dump_tim6_regs();
+                dump_dma_ch0_regs();
+            }
+        }
+    }
+}

dma_gpio/tests/integration.rs

@@ -0,0 +1,16 @@
+#![no_std]
+#![no_main]
+
+use stm32u5_blinky as _; // memory layout + panic handler
+
+// See https://crates.io/crates/defmt-test/0.3.0 for more documentation (e.g. about the 'state'
+// feature)
+#[defmt_test::tests]
+mod tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}

semestralka_1/.cargo/config.toml

@@ -0,0 +1,15 @@
+[build]
+target = "thumbv8m.main-none-eabihf"
+
+[target.thumbv8m.main-none-eabihf]
+runner = "probe-rs run --chip STM32U575ZITxQ"
+
+rustflags = [
+  "-C", "linker=rust-lld",
+  "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
+  "-C", "link-arg=--nmagic",
+]
+
+[package.metadata.cargo-flash]
+chip = "STM32U575ZIT"

semestralka_1/.gitignore

@@ -0,0 +1 @@
+/target

semestralka_1/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+authors = ["Priec <filippriec@gmail.com>"]
+name = "async_uart"
+edition = "2024"
+version = "0.1.0"
+
+
+[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 = { version = "0.9.1", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = "0.1.2"
+embassy-stm32 = { version = "0.4.0", features = ["unstable-pac", "stm32u575zi", "time-driver-any", "memory-x", "defmt"] }
+embassy-sync = "0.7.2"
+embassy-time = { version = "0.5.0", features = ["tick-hz-32_768"] }
+embassy-usb = "0.5.1"
+
+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-async = "0.6.0"
+embedded-io = "0.6.1"
+
+[dev-dependencies]
+defmt-test = "0.4.0"

semestralka_1/LICENSE-APACHE

@@ -0,0 +1,201 @@
+                              Apache License
+                        Version 2.0, January 2004
+                     http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
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+   and distribution as defined by Sections 1 through 9 of this document.
+
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+   the copyright owner that is granting the License.
+
+   "Legal Entity" shall mean the union of the acting entity and all
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+   direction or management of such entity, whether by contract or
+   otherwise, or (ii) ownership of fifty percent (50%) or more of the
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+
+   "You" (or "Your") shall mean an individual or Legal Entity
+   exercising permissions granted by this License.
+
+   "Source" form shall mean the preferred form for making modifications,
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+   not limited to compiled object code, generated documentation,
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+
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+END OF TERMS AND CONDITIONS
+
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+
+   To apply the Apache License to your work, attach the following
+   boilerplate notice, with the fields enclosed by brackets "[]"
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+   file or class name and description of purpose be included on the
+   same "printed page" as the copyright notice for easier
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+
+Copyright [yyyy] [name of copyright owner]
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
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+
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+
+Unless required by applicable law or agreed to in writing, software
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+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

semestralka_1/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

semestralka_1/Makefile

@@ -0,0 +1,23 @@
+TARGET = thumbv8m.main-none-eabihf
+CHIP = STM32U575ZI
+BIN = stm32u5-blinky
+MODE ?= release
+TARGET_DIR = target/$(TARGET)/$(MODE)
+ELF = $(TARGET_DIR)/$(BIN)
+PROBE = probe-rs
+
+.PHONY: all build flash clean empty
+
+all: build
+
+build:
+	cargo build --$(MODE)
+
+flash: build
+	$(PROBE) run --chip $(CHIP) $(ELF)
+
+empty:
+	$(PROBE) erase --chip $(CHIP)
+
+clean:
+	cargo clean

semestralka_1/README.md

@@ -0,0 +1,232 @@
+# `app-template`
+
+> Quickly set up a [`probe-rs`] + [`defmt`] + [`flip-link`] embedded project
+
+[`probe-rs`]: https://crates.io/crates/probe-rs
+[`defmt`]: https://github.com/knurling-rs/defmt
+[`flip-link`]: https://github.com/knurling-rs/flip-link
+
+## Dependencies
+
+### 1. `flip-link`:
+
+```bash
+cargo install flip-link
+```
+
+### 2. `probe-rs`:
+
+Install probe-rs by following the instructions at <https://probe.rs/docs/getting-started/installation/>.
+
+### 3. [`cargo-generate`]:
+
+```bash
+cargo install cargo-generate
+```
+
+[`cargo-generate`]: https://crates.io/crates/cargo-generate
+
+> *Note:* You can also just clone this repository instead of using `cargo-generate`, but this involves additional manual adjustments.
+
+## Setup
+
+### 1. Initialize the project template
+
+```bash
+cargo generate \
+    --git https://github.com/knurling-rs/app-template \
+    --branch main \
+    --name my-app
+```
+
+If you look into your new `my-app` folder, you'll find that there are a few `TODO`s in the files marking the properties you need to set.
+
+Let's walk through them together now.
+
+### 2. Set `probe-rs` chip
+
+Pick a chip from ` probe-rs chip list` and enter it into `.cargo/config.toml`.
+
+If, for example, you have a nRF52840 Development Kit as used in one of [our exercises], replace `{{chip}}` with `nRF52840_xxAA`.
+
+[our workshops]: https://rust-exercises.ferrous-systems.com
+
+```diff
+ # .cargo/config.toml
+-runner = ["probe-rs", "run", "--chip", "$CHIP", "--log-format=oneline"]
++runner = ["probe-rs", "run", "--chip", "nRF52840_xxAA", "--log-format=oneline"]
+```
+
+### 3. Adjust the compilation target
+
+In `.cargo/config.toml`, pick the right compilation target for your board.
+
+```diff
+ # .cargo/config.toml
+ [build]
+-target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+-# target = "thumbv7m-none-eabi"    # Cortex-M3
+-# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+-# target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
++target = "thumbv7em-none-eabihf" # Cortex-M4F (with FPU)
+```
+
+Add the target with `rustup`.
+
+```bash
+rustup target add thumbv7em-none-eabihf
+```
+
+### 4. Add a HAL as a dependency
+
+In `Cargo.toml`, list the Hardware Abstraction Layer (HAL) for your board as a dependency.
+
+For the nRF52840 you'll want to use the [`nrf52840-hal`].
+
+[`nrf52840-hal`]: https://crates.io/crates/nrf52840-hal
+
+```diff
+ # Cargo.toml
+ [dependencies]
+-# some-hal = "1.2.3"
++nrf52840-hal = "0.14.0"
+```
+
+⚠️ Note for RP2040 users ⚠️
+
+You will need to not just specify the `rp-hal` HAL, but a BSP (board support crate) which includes a second stage bootloader. Please find a list of available BSPs [here](https://github.com/rp-rs/rp-hal-boards#packages).
+
+### 5. Import your HAL
+
+Now that you have selected a HAL, fix the HAL import in `src/lib.rs`
+
+```diff
+ // my-app/src/lib.rs
+-// use some_hal as _; // memory layout
++use nrf52840_hal as _; // memory layout
+```
+
+### (6. Get a linker script)
+
+Some HAL crates require that you manually copy over a file called `memory.x` from the HAL to the root of your project. For nrf52840-hal, this is done automatically so no action is needed. For other HAL crates, see their documentation on where to find an example file.
+
+The `memory.x` file should look something like:
+
+```text
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 1024K
+  RAM   : ORIGIN = 0x20000000, LENGTH = 256K
+}
+```
+
+The `memory.x` file is included in the `cortex-m-rt` linker script `link.x`, and so `link.x` is the one you should tell `rustc` to use (see the `.cargo/config.toml` file where we do that).
+
+### 7. Run!
+
+You are now all set to `cargo-run` your first `defmt`-powered application!
+There are some examples in the `src/bin` directory.
+
+Start by `cargo run`-ning `my-app/src/bin/hello.rs`:
+
+```console
+$ # `rb` is an alias for `run --bin`
+$ cargo rb hello
+    Finished `dev` profile [optimized + debuginfo] target(s) in 0.01s
+     Running `probe-rs run --chip nrf52840_xxaa --log-format=oneline target/thumbv6m-none-eabi/debug/hello`
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.79 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+Hello, world!
+
+$ echo $?
+0
+```
+
+If you're running out of memory (`flip-link` bails with an overflow error), you can decrease the size of the device memory buffer by setting the `DEFMT_RTT_BUFFER_SIZE` environment variable. The default value is 1024 bytes, and powers of two should be used for optimal performance:
+
+```console
+$ DEFMT_RTT_BUFFER_SIZE=64 cargo rb hello
+```
+
+### (8. Set `rust-analyzer.linkedProjects`)
+
+If you are using [rust-analyzer] with VS Code for IDE-like features you can add following configuration to your `.vscode/settings.json` to make it work transparently across workspaces. Find the details of this option in the [RA docs].
+
+```json
+{
+    "rust-analyzer.linkedProjects": [
+        "Cargo.toml",
+        "firmware/Cargo.toml",
+    ]
+}
+```
+
+[RA docs]: https://rust-analyzer.github.io/manual.html#configuration
+[rust-analyzer]: https://rust-analyzer.github.io/
+
+## Running tests
+
+The template comes configured for running unit tests and integration tests on the target.
+
+Unit tests reside in the library crate and can test private API; the initial set of unit tests are in `src/lib.rs`.
+`cargo test --lib` will run those unit tests.
+
+```console
+$ cargo test --lib
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.15s
+     Running unittests src/lib.rs (target/thumbv6m-none-eabi/debug/deps/example-2b0d0e25d141bf57)
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.99 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.33 KiB/s (took 1s)                                                                                                                        Finished in 1.10s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Integration tests reside in the `tests` directory; the initial set of integration tests are in `tests/integration.rs`.
+`cargo test --test integration` will run those integration tests.
+Note that the argument of the `--test` flag must match the name of the test file in the `tests` directory.
+
+```console
+$ cargo test --test integration
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.10s
+     Running tests/integration.rs (target/thumbv6m-none-eabi/debug/deps/integration-aaaff41151f6a722)
+      Erasing ✔ 100% [####################]   8.00 KiB @  16.03 KiB/s (took 0s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Note that to add a new test file to the `tests` directory you also need to add a new `[[test]]` section to `Cargo.toml`.
+
+To run all the tests via `cargo test` the tests need to be explicitly disabled for all the existing binary targets.
+See `Cargo.toml` for details on how to do this.
+
+## Support
+
+`app-template` is part of the [Knurling] project, [Ferrous Systems]' effort at
+improving tooling used to develop for embedded systems.
+
+If you think that our work is useful, consider sponsoring it via [GitHub
+Sponsors].
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+licensed as above, without any additional terms or conditions.
+
+[Knurling]: https://knurling.ferrous-systems.com
+[Ferrous Systems]: https://ferrous-systems.com/
+[GitHub Sponsors]: https://github.com/sponsors/knurling-rs

semestralka_1/datasheet.txt

@@ -0,0 +1 @@
+https://www.ti.com/lit/ug/sprugp1/sprugp1.pdf?ts=1761641486453

semestralka_1/src/bin/main.rs

@@ -0,0 +1,157 @@
+// src/bin/main.rs
+
+#![no_std]
+#![no_main]
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::bind_interrupts;
+use embassy_stm32::peripherals;
+use embassy_stm32::peripherals::{PA2, PA3};
+use embassy_stm32::gpio::{Input, Output, Pull, Speed, Level};
+use embassy_stm32::Peripherals;
+use embassy_stm32::usart::{BufferedInterruptHandler, BufferedUart, Config};
+use embassy_stm32::timer::low_level::Timer as HardwareTimer;
+use embassy_stm32::interrupt::{self, typelevel::TIM2 as TIM2_IRQ, Priority};
+use embassy_stm32::peripherals::TIM2;
+use embedded_io_async::{Read, Write};
+use embassy_stm32::time::Hertz;
+use embassy_time::{Timer, Duration, Instant};
+use embassy_futures::yield_now;
+use embassy_futures::select::{select, Either};
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::pipe::Pipe;
+use embassy_sync::signal::Signal;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+use async_uart::safety::{preflight_and_suggest_yield_period, RX_PIPE_CAP, TX_PIPE_CAP};
+
+static UART_TX: Pipe<CriticalSectionRawMutex, TX_PIPE_CAP> = Pipe::new();
+static UART_RX: Pipe<CriticalSectionRawMutex, RX_PIPE_CAP> = Pipe::new();
+static TIM2_TICK: Signal<CriticalSectionRawMutex, ()> = Signal::new();
+
+bind_interrupts!(
+    struct Irqs {
+        USART1 => BufferedInterruptHandler<peripherals::USART1>;
+    }
+);
+
+#[embassy_executor::task]
+async fn uart_task(mut uart: BufferedUart<'static>) {
+    let mut rx_byte = [0u8; 1];
+    let mut tx_buf = [0u8; 64];
+    loop {
+        // Wait for either RX or TX events.
+        let rx_fut = uart.read(&mut rx_byte);
+        let tx_fut = async {
+            // Until there's outgoing data in TX pipe
+            let n = UART_TX.read(&mut tx_buf).await;
+            n
+        };
+        match select(rx_fut, tx_fut).await {
+            // Incoming data from UART hardware
+            Either::First(res) => {
+                if let Ok(_) = res {
+                    // Forward to RX pipe
+                    let _ = UART_RX.write(&rx_byte).await;
+                    let _ = UART_TX.try_write(&rx_byte);
+                }
+            }
+            // Outgoing data waiting in TX pipe
+            Either::Second(n) => {
+                unwrap!(uart.write(&tx_buf[..n]).await);
+            }
+        }
+    }
+}
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    info!("tititititi");
+    let p = embassy_stm32::init(Default::default());
+    static TX_BUF: StaticCell<[u8; 256]> = StaticCell::new();
+    static RX_BUF: StaticCell<[u8; 256]> = StaticCell::new();
+    let tx_buf = TX_BUF.init([0; 256]);
+    let rx_buf = RX_BUF.init([0; 256]);
+    let mut cfg = Config::default();
+    cfg.baudrate = 230_400;
+
+    // Call preflight and get the computed yield period
+    let yield_period = preflight_and_suggest_yield_period(cfg.baudrate);
+
+    let usart = BufferedUart::new(
+        p.USART1,
+        p.PA10, // RX
+        p.PA9,  // TX
+        tx_buf,
+        rx_buf,
+        Irqs,
+        cfg,
+    ).unwrap();
+    info!("starting uart task");
+    spawner.spawn(uart_task(usart)).unwrap();
+
+    let mut transfer: u32 = 16;
+    let mut rx_buf = [0u8; 64];
+    let mut last_yield = Instant::now();
+
+    // Software UART bits init
+    let mut tx = Output::new(p.PA2, Level::Low, Speed::Low);
+    let _rx = Input::new(p.PA3, Pull::Up);
+
+    let tim = HardwareTimer::new(p.TIM2);
+
+    // Configure for 230_400 Hz
+    tim.set_frequency(Hertz(cfg.baudrate*transfer));
+    tim.enable_update_interrupt(true);
+    tim.start();
+
+    tx.set_high();
+    loop {
+
+        TIM2_TICK.wait().await;
+        tx.set_low();
+        TIM2_TICK.wait().await;
+
+        Timer::after(Duration::from_millis(1000)).await;
+        // Poll RX pipe for new data (non-blocking)
+        if let Ok(n) = UART_RX.try_read(&mut rx_buf) {
+            if n > 0 {
+                if let Ok(s) = core::str::from_utf8(&rx_buf[..n]) {
+                    info!("RX got: {}", s);
+                } else {
+                    info!("RX got (non‑utf8): {:?}", &rx_buf[..n]);
+                }
+            }
+        }
+
+        // Guaranteed to yield before ISR RX buffer can overflow
+        if Instant::now().duration_since(last_yield) >= yield_period {
+            yield_now().await;
+            last_yield = Instant::now();
+            // info!("Yield mf {}", counter);
+        }
+        // Timer::after(Duration::from_micros(1)).await;
+        // Timer::after(Duration::from_secs(5)).await;
+    }
+}
+
+#[embassy_stm32::interrupt]
+fn TIM2() {
+    use embassy_stm32::timer::CoreInstance;
+
+    // Access TIM2 core registers directly.
+    let regs = unsafe {
+        embassy_stm32::pac::timer::TimCore::from_ptr(
+            <peripherals::TIM2 as CoreInstance>::regs(),
+        )
+    };
+
+    // Clear update flag to avoid retriggering.
+    let sr = regs.sr().read();
+    if sr.uif() {
+        regs.sr().modify(|r| r.set_uif(false));
+
+        // Signal the waiting task that a tick occurred.
+        TIM2_TICK.signal(());
+    }
+}

semestralka_1/src/lib.rs

@@ -0,0 +1,3 @@
+#![no_std]
+pub mod safety;
+// pub mod software_uart;

semestralka_1/src/safety.rs

@@ -0,0 +1,57 @@
+// src/safety.rs
+use defmt::info;
+use embassy_time::Duration;
+
+// ISR RX ring capacity = RX_BUF len
+const ISR_RX_BUF_CAP: usize = 256;
+// Yield 1/2 the time it takes to fill ISR RX ring.
+const YIELD_MARGIN_NUM: u32 = 1;
+const YIELD_MARGIN_DEN: u32 = 2;
+// Ensure RX_PIPE_CAP can hold this.
+const WORST_MAIN_LATENCY_MS: u32 = 20;
+
+pub const TX_PIPE_CAP: usize = 1024;
+pub const RX_PIPE_CAP: usize = 1024;
+
+
+
+/// Perform safety checks and compute yield timing to avoid buffer overflow.
+///
+/// # Panics
+/// Panics if pipe capacities are too small for the configured baud.
+pub fn preflight_and_suggest_yield_period(baud: u32) -> Duration {
+    // Approx bytes per second for 8N1 (10 bits per byte on the wire)
+    let bytes_per_sec = (baud / 10).max(1);
+
+    // Time until ISR RX ring fills, in microseconds.
+    let t_fill_us = (ISR_RX_BUF_CAP as u64) * 1_000_000u64 / (bytes_per_sec as u64);
+
+    // Choose a yield period as a fraction of t_fill.
+    let yield_us = (t_fill_us as u64)
+        .saturating_mul(YIELD_MARGIN_NUM as u64)
+        / (YIELD_MARGIN_DEN as u64);
+
+    // Verify RX pipe can absorb a worst-case app latency so uart_task
+    // can always forward without dropping when it runs.
+    let required_rx_pipe = (bytes_per_sec as u64) * (WORST_MAIN_LATENCY_MS as u64) / 1000;
+
+    if (RX_PIPE_CAP as u64) < required_rx_pipe {
+        core::panic!(
+            "RX pipe too small: have {}B, need >= {}B for {}ms at {} bps",
+            RX_PIPE_CAP, required_rx_pipe, WORST_MAIN_LATENCY_MS, baud
+        );
+    }
+
+    info!(
+        "Preflight: baud={}, rx_isr={}B, rx_pipe={}B, bytes/s={}, t_fill_us={}, yield_us={}",
+        baud,
+        ISR_RX_BUF_CAP,
+        RX_PIPE_CAP,
+        bytes_per_sec,
+        t_fill_us,
+        yield_us
+    );
+
+    // Never choose zero.
+    Duration::from_micros(yield_us.max(1) as u64)
+}

semestralka_1/src/software_uart/mod.rs

@@ -0,0 +1,4 @@
+// src/software_uart/mod.rs
+
+pub mod suart;
+pub use suart::*;

semestralka_1/src/software_uart/suart.rs

@@ -0,0 +1,19 @@
+// src/software_uart/suart.rs
+
+use embassy_stm32::peripherals::{PA2, PA3};
+use embassy_stm32::gpio::{Input, Output, Pull, Speed, Level};
+use embassy_stm32::Peripherals;
+use embassy_time::Timer;
+
+pub async fn suart_test(mut tx_pin: PA2, rx_pin: PA3) {
+    let mut tx = Output::new(tx_pin.into(), Level::Low, Speed::Low);
+    let _rx = Input::new(rx_pin.into(), Pull::Up);
+
+    loop {
+        tx.set_high();
+        Timer::after_millis(500).await;
+
+        tx.set_low();
+        Timer::after_millis(500).await;
+    }
+}

semestralka_1/tests/integration.rs

@@ -0,0 +1,14 @@
+#![no_std]
+#![no_main]
+
+// See https://crates.io/crates/defmt-test/0.3.0 for more documentation (e.g. about the 'state'
+// feature)
+#[defmt_test::tests]
+mod tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}

time_meas/.cargo/config.toml

@@ -0,0 +1,15 @@
+[build]
+target = "thumbv8m.main-none-eabihf"
+
+[target.thumbv8m.main-none-eabihf]
+runner = "probe-rs run --chip STM32U575ZITxQ"
+
+rustflags = [
+  "-C", "linker=rust-lld",
+  "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
+  "-C", "link-arg=--nmagic",
+]
+
+[package.metadata.cargo-flash]
+chip = "STM32U575ZIT"

time_meas/.gitignore

@@ -0,0 +1 @@
+/target

time_meas/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+authors = ["Priec <filippriec@gmail.com>"]
+name = "hal_rng"
+edition = "2024"
+version = "0.1.0"
+
+
+[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 = { version = "0.9.1", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = "0.1.2"
+embassy-stm32 = { version = "0.4.0", features = ["unstable-pac", "stm32u575zi", "time-driver-any", "memory-x", "defmt"] }
+embassy-sync = "0.7.2"
+embassy-time = { version = "0.5.0", features = ["tick-hz-32_768"] }
+embassy-usb = "0.5.1"
+
+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-async = "0.6.0"
+embedded-io = "0.6.1"

time_meas/LICENSE-APACHE

@@ -0,0 +1,201 @@
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+See the License for the specific language governing permissions and
+limitations under the License.

time_meas/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

time_meas/Makefile

@@ -0,0 +1,23 @@
+TARGET = thumbv8m.main-none-eabihf
+CHIP = STM32U575ZI
+BIN = stm32u5-blinky
+MODE ?= release
+TARGET_DIR = target/$(TARGET)/$(MODE)
+ELF = $(TARGET_DIR)/$(BIN)
+PROBE = probe-rs
+
+.PHONY: all build flash clean empty
+
+all: build
+
+build:
+	cargo build --$(MODE)
+
+flash: build
+	$(PROBE) run --chip $(CHIP) $(ELF)
+
+empty:
+	$(PROBE) erase --chip $(CHIP)
+
+clean:
+	cargo clean

time_meas/README.md

@@ -0,0 +1,232 @@
+# `app-template`
+
+> Quickly set up a [`probe-rs`] + [`defmt`] + [`flip-link`] embedded project
+
+[`probe-rs`]: https://crates.io/crates/probe-rs
+[`defmt`]: https://github.com/knurling-rs/defmt
+[`flip-link`]: https://github.com/knurling-rs/flip-link
+
+## Dependencies
+
+### 1. `flip-link`:
+
+```bash
+cargo install flip-link
+```
+
+### 2. `probe-rs`:
+
+Install probe-rs by following the instructions at <https://probe.rs/docs/getting-started/installation/>.
+
+### 3. [`cargo-generate`]:
+
+```bash
+cargo install cargo-generate
+```
+
+[`cargo-generate`]: https://crates.io/crates/cargo-generate
+
+> *Note:* You can also just clone this repository instead of using `cargo-generate`, but this involves additional manual adjustments.
+
+## Setup
+
+### 1. Initialize the project template
+
+```bash
+cargo generate \
+    --git https://github.com/knurling-rs/app-template \
+    --branch main \
+    --name my-app
+```
+
+If you look into your new `my-app` folder, you'll find that there are a few `TODO`s in the files marking the properties you need to set.
+
+Let's walk through them together now.
+
+### 2. Set `probe-rs` chip
+
+Pick a chip from ` probe-rs chip list` and enter it into `.cargo/config.toml`.
+
+If, for example, you have a nRF52840 Development Kit as used in one of [our exercises], replace `{{chip}}` with `nRF52840_xxAA`.
+
+[our workshops]: https://rust-exercises.ferrous-systems.com
+
+```diff
+ # .cargo/config.toml
+-runner = ["probe-rs", "run", "--chip", "$CHIP", "--log-format=oneline"]
++runner = ["probe-rs", "run", "--chip", "nRF52840_xxAA", "--log-format=oneline"]
+```
+
+### 3. Adjust the compilation target
+
+In `.cargo/config.toml`, pick the right compilation target for your board.
+
+```diff
+ # .cargo/config.toml
+ [build]
+-target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+-# target = "thumbv7m-none-eabi"    # Cortex-M3
+-# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+-# target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
++target = "thumbv7em-none-eabihf" # Cortex-M4F (with FPU)
+```
+
+Add the target with `rustup`.
+
+```bash
+rustup target add thumbv7em-none-eabihf
+```
+
+### 4. Add a HAL as a dependency
+
+In `Cargo.toml`, list the Hardware Abstraction Layer (HAL) for your board as a dependency.
+
+For the nRF52840 you'll want to use the [`nrf52840-hal`].
+
+[`nrf52840-hal`]: https://crates.io/crates/nrf52840-hal
+
+```diff
+ # Cargo.toml
+ [dependencies]
+-# some-hal = "1.2.3"
++nrf52840-hal = "0.14.0"
+```
+
+⚠️ Note for RP2040 users ⚠️
+
+You will need to not just specify the `rp-hal` HAL, but a BSP (board support crate) which includes a second stage bootloader. Please find a list of available BSPs [here](https://github.com/rp-rs/rp-hal-boards#packages).
+
+### 5. Import your HAL
+
+Now that you have selected a HAL, fix the HAL import in `src/lib.rs`
+
+```diff
+ // my-app/src/lib.rs
+-// use some_hal as _; // memory layout
++use nrf52840_hal as _; // memory layout
+```
+
+### (6. Get a linker script)
+
+Some HAL crates require that you manually copy over a file called `memory.x` from the HAL to the root of your project. For nrf52840-hal, this is done automatically so no action is needed. For other HAL crates, see their documentation on where to find an example file.
+
+The `memory.x` file should look something like:
+
+```text
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 1024K
+  RAM   : ORIGIN = 0x20000000, LENGTH = 256K
+}
+```
+
+The `memory.x` file is included in the `cortex-m-rt` linker script `link.x`, and so `link.x` is the one you should tell `rustc` to use (see the `.cargo/config.toml` file where we do that).
+
+### 7. Run!
+
+You are now all set to `cargo-run` your first `defmt`-powered application!
+There are some examples in the `src/bin` directory.
+
+Start by `cargo run`-ning `my-app/src/bin/hello.rs`:
+
+```console
+$ # `rb` is an alias for `run --bin`
+$ cargo rb hello
+    Finished `dev` profile [optimized + debuginfo] target(s) in 0.01s
+     Running `probe-rs run --chip nrf52840_xxaa --log-format=oneline target/thumbv6m-none-eabi/debug/hello`
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.79 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+Hello, world!
+
+$ echo $?
+0
+```
+
+If you're running out of memory (`flip-link` bails with an overflow error), you can decrease the size of the device memory buffer by setting the `DEFMT_RTT_BUFFER_SIZE` environment variable. The default value is 1024 bytes, and powers of two should be used for optimal performance:
+
+```console
+$ DEFMT_RTT_BUFFER_SIZE=64 cargo rb hello
+```
+
+### (8. Set `rust-analyzer.linkedProjects`)
+
+If you are using [rust-analyzer] with VS Code for IDE-like features you can add following configuration to your `.vscode/settings.json` to make it work transparently across workspaces. Find the details of this option in the [RA docs].
+
+```json
+{
+    "rust-analyzer.linkedProjects": [
+        "Cargo.toml",
+        "firmware/Cargo.toml",
+    ]
+}
+```
+
+[RA docs]: https://rust-analyzer.github.io/manual.html#configuration
+[rust-analyzer]: https://rust-analyzer.github.io/
+
+## Running tests
+
+The template comes configured for running unit tests and integration tests on the target.
+
+Unit tests reside in the library crate and can test private API; the initial set of unit tests are in `src/lib.rs`.
+`cargo test --lib` will run those unit tests.
+
+```console
+$ cargo test --lib
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.15s
+     Running unittests src/lib.rs (target/thumbv6m-none-eabi/debug/deps/example-2b0d0e25d141bf57)
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.99 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.33 KiB/s (took 1s)                                                                                                                        Finished in 1.10s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Integration tests reside in the `tests` directory; the initial set of integration tests are in `tests/integration.rs`.
+`cargo test --test integration` will run those integration tests.
+Note that the argument of the `--test` flag must match the name of the test file in the `tests` directory.
+
+```console
+$ cargo test --test integration
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.10s
+     Running tests/integration.rs (target/thumbv6m-none-eabi/debug/deps/integration-aaaff41151f6a722)
+      Erasing ✔ 100% [####################]   8.00 KiB @  16.03 KiB/s (took 0s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Note that to add a new test file to the `tests` directory you also need to add a new `[[test]]` section to `Cargo.toml`.
+
+To run all the tests via `cargo test` the tests need to be explicitly disabled for all the existing binary targets.
+See `Cargo.toml` for details on how to do this.
+
+## Support
+
+`app-template` is part of the [Knurling] project, [Ferrous Systems]' effort at
+improving tooling used to develop for embedded systems.
+
+If you think that our work is useful, consider sponsoring it via [GitHub
+Sponsors].
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+licensed as above, without any additional terms or conditions.
+
+[Knurling]: https://knurling.ferrous-systems.com
+[Ferrous Systems]: https://ferrous-systems.com/
+[GitHub Sponsors]: https://github.com/sponsors/knurling-rs

time_meas/src/bin/main.rs

@@ -0,0 +1,84 @@
+// src/bin/main.rs
+#![no_std]
+#![no_main]
+
+use core::sync::atomic::{AtomicUsize, Ordering};
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::pac;
+use embassy_stm32::interrupt::InterruptExt;
+use embassy_stm32::timer::low_level::{CountingMode, Timer as LLTimer};
+use embassy_stm32::time::khz;
+use embassy_stm32::interrupt;
+use {defmt_rtt as _, panic_probe as _};
+
+// Pointer to the local `counter` so the ISR can read it with zero per-iteration overhead.
+static COUNTER_PTR: AtomicUsize = AtomicUsize::new(0);
+
+// NVIC handler for TIM2
+#[interrupt]
+fn TIM2() {
+    // Clear UIF, stop the timer
+    pac::TIM2.sr().modify(|r| r.set_uif(false));
+    pac::TIM2.cr1().modify(|r| r.set_cen(false));
+
+    // Snapshot the counter that the loop has been incrementing
+    let ptr = COUNTER_PTR.load(Ordering::Relaxed) as *const u32;
+    let count = unsafe { core::ptr::read_volatile(ptr) };
+
+    info!("10 seconds elapsed, counter = {}", count);
+
+    // Halt
+    loop {
+        cortex_m::asm::bkpt();
+    }
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Start");
+    let p = embassy_stm32::init(Default::default());
+
+    // Configure TIM2
+    let mut tim2 = LLTimer::new(p.TIM2);
+    tim2.stop();
+    tim2.set_counting_mode(CountingMode::EdgeAlignedUp);
+
+    // Make the timer tick at 10 kHz. Driver derives PSC from RCC, so timing is exact.
+    tim2.set_tick_freq(khz(10));
+
+    // 10 seconds => 10_000 ticks/s * 10 s = 100_000 ticks. ARR is inclusive: set to 100_000 - 1.
+    tim2.set_max_compare_value(100_000 - 1);
+
+    // One-pulse mode (auto-stop after the first update event)
+    tim2.regs_core().cr1().modify(|r| r.set_opm(true));
+
+    // Ensure no pending UIF from the UG we generated during PSC/ARR programming.
+    // Important: do this BEFORE enabling UIE/NVIC to avoid an immediate ISR.
+    let _ = tim2.clear_update_interrupt();
+
+    // Enable update interrupt, reset counter to 0. Do not start yet.
+    tim2.enable_update_interrupt(true);
+    tim2.reset();
+
+    // Expose the address of the loop counter BEFORE enabling the NVIC so the ISR
+    // never runs before COUNTER_PTR is valid.
+    let mut counter: u32 = 0;
+    COUNTER_PTR.store(&counter as *const u32 as usize, Ordering::Relaxed);
+
+    // Unpend and enable NVIC for TIM2, then start the timer.
+    unsafe {
+        embassy_stm32::interrupt::TIM2.unpend();
+        embassy_stm32::interrupt::TIM2.enable();
+    }
+    tim2.start();
+
+    // Tight CPU loop for benchmarking
+    loop {
+        counter = counter.wrapping_add(1);
+
+        if counter % 10000 == 0 {
+            info!("CPU doing other work: {}", counter);
+        }
+    }
+}

time_meas/src/lib.rs

@@ -0,0 +1 @@
+#![no_std]

time_meas/tests/integration.rs

@@ -0,0 +1,16 @@
+#![no_std]
+#![no_main]
+
+use stm32u5_blinky as _; // memory layout + panic handler
+
+// See https://crates.io/crates/defmt-test/0.3.0 for more documentation (e.g. about the 'state'
+// feature)
+#[defmt_test::tests]
+mod tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}

usart_async_buffered_generalized/src/bin/main.rs

@@ -59,7 +59,8 @@ async fn uart_task(mut uart: BufferedUart<'static>) {
 
 pub async fn send_uart(data: &[u8]) {
     let mut v: Vec<u8, MAX_MSG> = Vec::new();
-    let _ = v.extend_from_slice(data); // truncate if too long
+    // TODO truncation nonsense as a temp solution
+    let _ = v.extend_from_slice(data);
     UART_TX.send(v).await;
 }
 
@@ -101,5 +102,6 @@ async fn main(spawner: Spawner) {
             // Send whenever you want; the UART task performs the actual write.
             send_uart(b"Hello\r\n").await;
         }
+        // Timer::after(Duration::from_micros(1)).await;
     }
 }

usart_async_buffered_generalized2/.cargo/config.toml

@@ -0,0 +1,15 @@
+[build]
+target = "thumbv8m.main-none-eabihf"
+
+[target.thumbv8m.main-none-eabihf]
+runner = "probe-rs run --chip STM32U575ZITxQ"
+
+rustflags = [
+  "-C", "linker=rust-lld",
+  "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
+  "-C", "link-arg=--nmagic",
+]
+
+[package.metadata.cargo-flash]
+chip = "STM32U575ZIT"

usart_async_buffered_generalized2/.gitignore

@@ -0,0 +1 @@
+/target

usart_async_buffered_generalized2/Cargo.toml

@@ -0,0 +1,33 @@
+[package]
+authors = ["Priec <filippriec@gmail.com>"]
+name = "async_uart"
+edition = "2024"
+version = "0.1.0"
+
+
+[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 = { version = "0.9.1", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = "0.1.2"
+embassy-stm32 = { version = "0.4.0", features = ["unstable-pac", "stm32u575zi", "time-driver-any", "memory-x", "defmt"] }
+embassy-sync = "0.7.2"
+embassy-time = { version = "0.5.0", features = ["tick-hz-32_768"] }
+embassy-usb = "0.5.1"
+
+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-async = "0.6.0"
+embedded-io = "0.6.1"
+
+[dev-dependencies]
+defmt-test = "0.4.0"

usart_async_buffered_generalized2/LICENSE-APACHE

@@ -0,0 +1,201 @@
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usart_async_buffered_generalized2/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
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+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

usart_async_buffered_generalized2/Makefile

@@ -0,0 +1,23 @@
+TARGET = thumbv8m.main-none-eabihf
+CHIP = STM32U575ZI
+BIN = stm32u5-blinky
+MODE ?= release
+TARGET_DIR = target/$(TARGET)/$(MODE)
+ELF = $(TARGET_DIR)/$(BIN)
+PROBE = probe-rs
+
+.PHONY: all build flash clean empty
+
+all: build
+
+build:
+	cargo build --$(MODE)
+
+flash: build
+	$(PROBE) run --chip $(CHIP) $(ELF)
+
+empty:
+	$(PROBE) erase --chip $(CHIP)
+
+clean:
+	cargo clean

usart_async_buffered_generalized2/README.md

@@ -0,0 +1,232 @@
+# `app-template`
+
+> Quickly set up a [`probe-rs`] + [`defmt`] + [`flip-link`] embedded project
+
+[`probe-rs`]: https://crates.io/crates/probe-rs
+[`defmt`]: https://github.com/knurling-rs/defmt
+[`flip-link`]: https://github.com/knurling-rs/flip-link
+
+## Dependencies
+
+### 1. `flip-link`:
+
+```bash
+cargo install flip-link
+```
+
+### 2. `probe-rs`:
+
+Install probe-rs by following the instructions at <https://probe.rs/docs/getting-started/installation/>.
+
+### 3. [`cargo-generate`]:
+
+```bash
+cargo install cargo-generate
+```
+
+[`cargo-generate`]: https://crates.io/crates/cargo-generate
+
+> *Note:* You can also just clone this repository instead of using `cargo-generate`, but this involves additional manual adjustments.
+
+## Setup
+
+### 1. Initialize the project template
+
+```bash
+cargo generate \
+    --git https://github.com/knurling-rs/app-template \
+    --branch main \
+    --name my-app
+```
+
+If you look into your new `my-app` folder, you'll find that there are a few `TODO`s in the files marking the properties you need to set.
+
+Let's walk through them together now.
+
+### 2. Set `probe-rs` chip
+
+Pick a chip from ` probe-rs chip list` and enter it into `.cargo/config.toml`.
+
+If, for example, you have a nRF52840 Development Kit as used in one of [our exercises], replace `{{chip}}` with `nRF52840_xxAA`.
+
+[our workshops]: https://rust-exercises.ferrous-systems.com
+
+```diff
+ # .cargo/config.toml
+-runner = ["probe-rs", "run", "--chip", "$CHIP", "--log-format=oneline"]
++runner = ["probe-rs", "run", "--chip", "nRF52840_xxAA", "--log-format=oneline"]
+```
+
+### 3. Adjust the compilation target
+
+In `.cargo/config.toml`, pick the right compilation target for your board.
+
+```diff
+ # .cargo/config.toml
+ [build]
+-target = "thumbv6m-none-eabi"    # Cortex-M0 and Cortex-M0+
+-# target = "thumbv7m-none-eabi"    # Cortex-M3
+-# target = "thumbv7em-none-eabi"   # Cortex-M4 and Cortex-M7 (no FPU)
+-# target = "thumbv7em-none-eabihf" # Cortex-M4F and Cortex-M7F (with FPU)
++target = "thumbv7em-none-eabihf" # Cortex-M4F (with FPU)
+```
+
+Add the target with `rustup`.
+
+```bash
+rustup target add thumbv7em-none-eabihf
+```
+
+### 4. Add a HAL as a dependency
+
+In `Cargo.toml`, list the Hardware Abstraction Layer (HAL) for your board as a dependency.
+
+For the nRF52840 you'll want to use the [`nrf52840-hal`].
+
+[`nrf52840-hal`]: https://crates.io/crates/nrf52840-hal
+
+```diff
+ # Cargo.toml
+ [dependencies]
+-# some-hal = "1.2.3"
++nrf52840-hal = "0.14.0"
+```
+
+⚠️ Note for RP2040 users ⚠️
+
+You will need to not just specify the `rp-hal` HAL, but a BSP (board support crate) which includes a second stage bootloader. Please find a list of available BSPs [here](https://github.com/rp-rs/rp-hal-boards#packages).
+
+### 5. Import your HAL
+
+Now that you have selected a HAL, fix the HAL import in `src/lib.rs`
+
+```diff
+ // my-app/src/lib.rs
+-// use some_hal as _; // memory layout
++use nrf52840_hal as _; // memory layout
+```
+
+### (6. Get a linker script)
+
+Some HAL crates require that you manually copy over a file called `memory.x` from the HAL to the root of your project. For nrf52840-hal, this is done automatically so no action is needed. For other HAL crates, see their documentation on where to find an example file.
+
+The `memory.x` file should look something like:
+
+```text
+MEMORY
+{
+  FLASH : ORIGIN = 0x00000000, LENGTH = 1024K
+  RAM   : ORIGIN = 0x20000000, LENGTH = 256K
+}
+```
+
+The `memory.x` file is included in the `cortex-m-rt` linker script `link.x`, and so `link.x` is the one you should tell `rustc` to use (see the `.cargo/config.toml` file where we do that).
+
+### 7. Run!
+
+You are now all set to `cargo-run` your first `defmt`-powered application!
+There are some examples in the `src/bin` directory.
+
+Start by `cargo run`-ning `my-app/src/bin/hello.rs`:
+
+```console
+$ # `rb` is an alias for `run --bin`
+$ cargo rb hello
+    Finished `dev` profile [optimized + debuginfo] target(s) in 0.01s
+     Running `probe-rs run --chip nrf52840_xxaa --log-format=oneline target/thumbv6m-none-eabi/debug/hello`
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.79 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+Hello, world!
+
+$ echo $?
+0
+```
+
+If you're running out of memory (`flip-link` bails with an overflow error), you can decrease the size of the device memory buffer by setting the `DEFMT_RTT_BUFFER_SIZE` environment variable. The default value is 1024 bytes, and powers of two should be used for optimal performance:
+
+```console
+$ DEFMT_RTT_BUFFER_SIZE=64 cargo rb hello
+```
+
+### (8. Set `rust-analyzer.linkedProjects`)
+
+If you are using [rust-analyzer] with VS Code for IDE-like features you can add following configuration to your `.vscode/settings.json` to make it work transparently across workspaces. Find the details of this option in the [RA docs].
+
+```json
+{
+    "rust-analyzer.linkedProjects": [
+        "Cargo.toml",
+        "firmware/Cargo.toml",
+    ]
+}
+```
+
+[RA docs]: https://rust-analyzer.github.io/manual.html#configuration
+[rust-analyzer]: https://rust-analyzer.github.io/
+
+## Running tests
+
+The template comes configured for running unit tests and integration tests on the target.
+
+Unit tests reside in the library crate and can test private API; the initial set of unit tests are in `src/lib.rs`.
+`cargo test --lib` will run those unit tests.
+
+```console
+$ cargo test --lib
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.15s
+     Running unittests src/lib.rs (target/thumbv6m-none-eabi/debug/deps/example-2b0d0e25d141bf57)
+      Erasing ✔ 100% [####################]   8.00 KiB @  15.99 KiB/s (took 1s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.33 KiB/s (took 1s)                                                                                                                        Finished in 1.10s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Integration tests reside in the `tests` directory; the initial set of integration tests are in `tests/integration.rs`.
+`cargo test --test integration` will run those integration tests.
+Note that the argument of the `--test` flag must match the name of the test file in the `tests` directory.
+
+```console
+$ cargo test --test integration
+   Compiling example v0.1.0 (./knurling-rs/example)
+    Finished `test` profile [optimized + debuginfo] target(s) in 0.10s
+     Running tests/integration.rs (target/thumbv6m-none-eabi/debug/deps/integration-aaaff41151f6a722)
+      Erasing ✔ 100% [####################]   8.00 KiB @  16.03 KiB/s (took 0s)
+  Programming ✔ 100% [####################]   8.00 KiB @  13.19 KiB/s (took 1s)                                                                                                                        Finished in 1.11s
+(1/1) running `it_works`...
+all tests passed!
+```
+
+Note that to add a new test file to the `tests` directory you also need to add a new `[[test]]` section to `Cargo.toml`.
+
+To run all the tests via `cargo test` the tests need to be explicitly disabled for all the existing binary targets.
+See `Cargo.toml` for details on how to do this.
+
+## Support
+
+`app-template` is part of the [Knurling] project, [Ferrous Systems]' effort at
+improving tooling used to develop for embedded systems.
+
+If you think that our work is useful, consider sponsoring it via [GitHub
+Sponsors].
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or
+  http://www.apache.org/licenses/LICENSE-2.0)
+
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+licensed as above, without any additional terms or conditions.
+
+[Knurling]: https://knurling.ferrous-systems.com
+[Ferrous Systems]: https://ferrous-systems.com/
+[GitHub Sponsors]: https://github.com/sponsors/knurling-rs

usart_async_buffered_generalized2/src/bin/main.rs

@@ -0,0 +1,63 @@
+// src/bin/main.rs
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use {defmt_rtt as _, panic_probe as _};
+
+use embassy_executor::Spawner;
+use embassy_stm32::usart::{BufferedInterruptHandler, BufferedUart, Config};
+use embassy_stm32::bind_interrupts;
+use embassy_stm32::peripherals;
+use embassy_time::Instant;
+use static_cell::StaticCell;
+
+use async_uart::uart::usart1;
+
+bind_interrupts!(struct Irqs {
+    USART1 => BufferedInterruptHandler<peripherals::USART1>;
+});
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    info!("boot");
+    let p = embassy_stm32::init(Default::default());
+
+    let mut cfg = Config::default();
+    cfg.baudrate = 230_400;
+
+    static TX_BUF: StaticCell<[u8; 256]> = StaticCell::new();
+    static RX_BUF: StaticCell<[u8; 256]> = StaticCell::new();
+
+    let uart = 
+        BufferedUart::new(
+            p.USART1,
+            p.PA10,
+            p.PA9,
+            TX_BUF.init([0; 256]),
+            RX_BUF.init([0; 256]),
+            Irqs,
+            cfg,
+        ).unwrap();
+    let handle = usart1::setup_and_spawn(&spawner, uart, cfg.baudrate);
+
+    let mut rx_buf = [0u8; 64];
+    let mut last_yield = Instant::now();
+
+    loop {
+        if let Ok(n) = handle.rx.try_read(&mut rx_buf) {
+            if n > 0 {
+                if let Ok(s) = core::str::from_utf8(&rx_buf[..n]) {
+                    info!("RX got: {}", s);
+                } else {
+                    info!("RX got (non‑utf8): {:?}", &rx_buf[..n]);
+                }
+            }
+        }
+
+        if Instant::now().duration_since(last_yield) >= handle.yield_period {
+            embassy_futures::yield_now().await;
+            last_yield = Instant::now();
+        }
+    }
+}

usart_async_buffered_generalized2/src/lib.rs

@@ -0,0 +1,2 @@
+#![no_std]
+pub mod uart;

usart_async_buffered_generalized2/src/uart/driver.rs

@@ -0,0 +1,65 @@
+// src/uart/driver.rs
+use defmt::unwrap;
+use embassy_executor::Spawner;
+use embassy_futures::select::{select, Either};
+use embassy_stm32::usart::BufferedUart;
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::pipe::Pipe;
+use embassy_time::Duration;
+use embedded_io_async::{Read, Write};
+
+use crate::uart::safety::{RX_PIPE_CAP, TX_PIPE_CAP};
+
+pub struct UartHandle {
+    pub tx: &'static Pipe<CriticalSectionRawMutex, TX_PIPE_CAP>,
+    pub rx: &'static Pipe<CriticalSectionRawMutex, RX_PIPE_CAP>,
+    pub yield_period: Duration,
+}
+
+#[embassy_executor::task]
+pub async fn uart_task(
+    mut uart: BufferedUart<'static>,
+    tx_pipe: &'static Pipe<CriticalSectionRawMutex, TX_PIPE_CAP>,
+    rx_pipe: &'static Pipe<CriticalSectionRawMutex, RX_PIPE_CAP>,
+) {
+    let mut rx_byte = [0u8; 1];
+    let mut tx_buf = [0u8; 64];
+
+    loop {
+        let rx_fut = uart.read(&mut rx_byte);
+        let tx_fut = async {
+            let n = tx_pipe.read(&mut tx_buf).await;
+            n
+        };
+
+        match select(rx_fut, tx_fut).await {
+            // Incoming data from UART hardware
+            Either::First(res) => {
+                if let Ok(_) = res {
+                    // Forward to RX pipe and echo to TX pipe (same behavior as before)
+                    let _ = rx_pipe.write(&rx_byte).await;
+                    let _ = tx_pipe.try_write(&rx_byte);
+                }
+            }
+            // Outgoing data waiting in TX pipe
+            Either::Second(n) => {
+                unwrap!(uart.write(&tx_buf[..n]).await);
+            }
+        }
+    }
+}
+
+pub fn spawn_for(
+    spawner: &Spawner,
+    uart: BufferedUart<'static>,
+    tx_pipe: &'static Pipe<CriticalSectionRawMutex, TX_PIPE_CAP>,
+    rx_pipe: &'static Pipe<CriticalSectionRawMutex, RX_PIPE_CAP>,
+    yield_period: Duration,
+) -> UartHandle {
+    spawner.spawn(uart_task(uart, tx_pipe, rx_pipe)).unwrap();
+    UartHandle {
+        tx: tx_pipe,
+        rx: rx_pipe,
+        yield_period,
+    }
+}

usart_async_buffered_generalized2/src/uart/mod.rs

@@ -0,0 +1,4 @@
+// src/uart/mod.rs
+pub mod driver;
+pub mod usart1;
+pub mod safety;

usart_async_buffered_generalized2/src/uart/safety.rs

@@ -0,0 +1,57 @@
+// src/safety.rs
+use defmt::info;
+use embassy_time::Duration;
+
+// ISR RX ring capacity = RX_BUF len
+const ISR_RX_BUF_CAP: usize = 256;
+// Yield 1/2 the time it takes to fill ISR RX ring.
+const YIELD_MARGIN_NUM: u32 = 1;
+const YIELD_MARGIN_DEN: u32 = 2;
+// Ensure RX_PIPE_CAP can hold this.
+const WORST_MAIN_LATENCY_MS: u32 = 20;
+
+pub const TX_PIPE_CAP: usize = 1024;
+pub const RX_PIPE_CAP: usize = 1024;
+
+
+
+/// Perform safety checks and compute yield timing to avoid buffer overflow.
+///
+/// # Panics
+/// Panics if pipe capacities are too small for the configured baud.
+pub fn preflight_and_suggest_yield_period(baud: u32) -> Duration {
+    // Approx bytes per second for 8N1 (10 bits per byte on the wire)
+    let bytes_per_sec = (baud / 10).max(1);
+
+    // Time until ISR RX ring fills, in microseconds.
+    let t_fill_us = (ISR_RX_BUF_CAP as u64) * 1_000_000u64 / (bytes_per_sec as u64);
+
+    // Choose a yield period as a fraction of t_fill.
+    let yield_us = (t_fill_us as u64)
+        .saturating_mul(YIELD_MARGIN_NUM as u64)
+        / (YIELD_MARGIN_DEN as u64);
+
+    // Verify RX pipe can absorb a worst-case app latency so uart_task
+    // can always forward without dropping when it runs.
+    let required_rx_pipe = (bytes_per_sec as u64) * (WORST_MAIN_LATENCY_MS as u64) / 1000;
+
+    if (RX_PIPE_CAP as u64) < required_rx_pipe {
+        core::panic!(
+            "RX pipe too small: have {}B, need >= {}B for {}ms at {} bps",
+            RX_PIPE_CAP, required_rx_pipe, WORST_MAIN_LATENCY_MS, baud
+        );
+    }
+
+    info!(
+        "Preflight: baud={}, rx_isr={}B, rx_pipe={}B, bytes/s={}, t_fill_us={}, yield_us={}",
+        baud,
+        ISR_RX_BUF_CAP,
+        RX_PIPE_CAP,
+        bytes_per_sec,
+        t_fill_us,
+        yield_us
+    );
+
+    // Never choose zero.
+    Duration::from_micros(yield_us.max(1) as u64)
+}

usart_async_buffered_generalized2/src/uart/usart1.rs

@@ -0,0 +1,23 @@
+// src/uart/usart1.rs
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+use embassy_sync::pipe::Pipe;
+use embassy_time::Duration;
+
+use crate::uart::safety::{preflight_and_suggest_yield_period, RX_PIPE_CAP, TX_PIPE_CAP};
+use crate::uart::driver::{spawn_for, UartHandle};
+
+// Static pipes and buffers
+static UART1_TX_PIPE: Pipe<CriticalSectionRawMutex, TX_PIPE_CAP> = Pipe::new();
+static UART1_RX_PIPE: Pipe<CriticalSectionRawMutex, RX_PIPE_CAP> = Pipe::new();
+
+pub fn setup_and_spawn(
+    spawner: &Spawner,
+    uart: embassy_stm32::usart::BufferedUart<'static>,
+    baudrate: u32,
+) -> UartHandle {
+    let yield_period: Duration = preflight_and_suggest_yield_period(baudrate);
+    info!("USART1 initialized");
+    spawn_for(spawner, uart, &UART1_TX_PIPE, &UART1_RX_PIPE, yield_period)
+}

usart_async_buffered_generalized2/tests/integration.rs

@@ -0,0 +1,14 @@
+#![no_std]
+#![no_main]
+
+// See https://crates.io/crates/defmt-test/0.3.0 for more documentation (e.g. about the 'state'
+// feature)
+#[defmt_test::tests]
+mod tests {
+    use defmt::assert;
+
+    #[test]
+    fn it_works() {
+        assert!(true)
+    }
+}