init basic examples and setup

examples/blinky-timer/Cargo.toml

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+[package]
+name = "blinky-timer"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m.workspace = true
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+nb.workspace = true
+panic-probe.workspace = true
+stm32f1xx-hal = { workspace = true, features = ["medium", "stm32f103"] }

examples/blinky-timer/build.rs

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+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/blinky-timer/src/main.rs

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+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::entry;
+use defmt::info;
+use defmt_rtt as _;
+use nb::block;
+use panic_probe as _;
+use stm32f1xx_hal::{pac, prelude::*, timer::Timer};
+
+const BLINK_HZ: u32 = 2;
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let cp = cortex_m::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.constrain();
+    let mut gpioc = dp.GPIOC.split(&mut rcc);
+    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
+
+    // A timer gives stable periodic work without burning cycles in a delay loop.
+    let mut timer = Timer::syst(cp.SYST, &rcc.clocks).counter_hz();
+    timer.start(BLINK_HZ.Hz()).unwrap();
+
+    led.set_high();
+    info!("blinky-timer: {} Hz toggle loop", BLINK_HZ);
+
+    loop {
+        block!(timer.wait()).unwrap();
+        led.toggle();
+        info!("tick");
+    }
+}