Nix flake for rustup dev shell

Remove unnecessary nop from main loops

.cargo/config.toml

@@ -1,13 +1,13 @@
 [target.thumbv7m-none-eabi]
 # uncomment this to make `cargo run` execute programs on QEMU
-# runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
+runner = "qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel"
 
 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
 # uncomment ONE of these three option to make `cargo run` start a GDB session
 # which option to pick depends on your system
 # runner = "arm-none-eabi-gdb -q -x openocd.gdb"
 # runner = "gdb-multiarch -q -x openocd.gdb"
-# runner = "gdb -q -x openocd.gdb"
+runner = "gdb -q -x openocd.gdb"
 
 rustflags = [
   # Previously, the linker arguments --nmagic and -Tlink.x were set here.
@@ -29,9 +29,9 @@ rustflags = [
 [build]
 # Pick ONE of these default compilation targets
 # target = "thumbv6m-none-eabi"        # Cortex-M0 and Cortex-M0+
-target = "thumbv7m-none-eabi"        # Cortex-M3
+# 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 and Cortex-M7F (with FPU)
 # target = "thumbv8m.base-none-eabi"   # Cortex-M23
 # target = "thumbv8m.main-none-eabi"   # Cortex-M33 (no FPU)
 # target = "thumbv8m.main-none-eabihf" # Cortex-M33 (with FPU)

Cargo.toml

@@ -1,36 +1,37 @@
 [package]
-authors = ["{{authors}}"]
+authors = ["jasper"]
 edition = "2018"
 readme = "README.md"
-name = "{{project-name}}"
+name = "embedded-rs"
 version = "0.1.0"
 
 [dependencies]
-cortex-m = "0.6.0"
-cortex-m-rt = "0.6.10"
-cortex-m-semihosting = "0.3.3"
-panic-halt = "0.2.0"
+cortex-m = { version = "0.7.6", features = ["critical-section-single-core"] }
+cortex-m-rt = "0.7"
+cortex-m-semihosting = "0.5"
+panic-halt = "1.0.0"
+# stm32f3 = "0.7.1"
 
 # Uncomment for the panic example.
 # panic-itm = "0.4.1"
 
 # Uncomment for the allocator example.
-# alloc-cortex-m = "0.4.0"
+# embedded-alloc = "0.6.0"
 
 # Uncomment for the device example.
 # Update `memory.x`, set target to `thumbv7em-none-eabihf` in `.cargo/config`,
-# and then use `cargo build --examples device` to build it.
-# [dependencies.stm32f3]
-# features = ["stm32f303", "rt"]
-# version = "0.7.1"
+# and then use `cargo build --example device` to build it.
+[dependencies.stm32f3]
+features = ["stm32f303", "rt"]
+version = "^0.16.0"
 
 # this lets you use `cargo fix`!
 [[bin]]
-name = "{{project-name}}"
+name = "embedded-rs"
 test = false
 bench = false
 
 [profile.release]
 codegen-units = 1 # better optimizations
-debug = true # symbols are nice and they don't increase the size on Flash
-lto = true # better optimizations
+debug = true      # symbols are nice and they don't increase the size on Flash
+lto = true        # better optimizations

examples/allocator.rs

@@ -1,15 +1,14 @@
 //! How to use the heap and a dynamic memory allocator
 //!
-//! This example depends on the alloc-cortex-m crate so you'll have to add it to your Cargo.toml:
+//! This example depends on the embedded-alloc crate so you'll have to add it to your Cargo.toml:
 //!
 //! ``` text
 //! # or edit the Cargo.toml file manually
-//! $ cargo add alloc-cortex-m
+//! $ cargo add embedded-alloc
 //! ```
 //!
 //! ---
 
-#![feature(alloc_error_handler)]
 #![no_main]
 #![no_std]
 
@@ -17,28 +16,33 @@ extern crate alloc;
 use panic_halt as _;
 
 use self::alloc::vec;
-use core::alloc::Layout;
+use core::ptr::addr_of_mut;
 
-use alloc_cortex_m::CortexMHeap;
-use cortex_m::asm;
+// Linked-List First Fit Heap allocator (feature = "llff")
+use embedded_alloc::LlffHeap as Heap;
+// Two-Level Segregated Fit Heap allocator (feature = "tlsf")
+// use embedded_alloc::TlsfHeap as Heap;
 use cortex_m_rt::entry;
 use cortex_m_semihosting::{hprintln, debug};
 
 // this is the allocator the application will use
 #[global_allocator]
-static ALLOCATOR: CortexMHeap = CortexMHeap::empty();
-
-const HEAP_SIZE: usize = 1024; // in bytes
+static HEAP: Heap = Heap::empty();
 
 #[entry]
 fn main() -> ! {
     // Initialize the allocator BEFORE you use it
-    unsafe { ALLOCATOR.init(cortex_m_rt::heap_start() as usize, HEAP_SIZE) }
+    {
+        use core::mem::MaybeUninit;
+        const HEAP_SIZE: usize = 1024;
+        static mut HEAP_MEM: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
+        unsafe { HEAP.init(addr_of_mut!(HEAP_MEM) as usize, HEAP_SIZE) }
+    }
 
     // Growable array allocated on the heap
     let xs = vec![0, 1, 2];
 
-    hprintln!("{:?}", xs).unwrap();
+    hprintln!("{:?}", xs);
 
     // exit QEMU
     // NOTE do not run this on hardware; it can corrupt OpenOCD state
@@ -46,11 +50,3 @@ fn main() -> ! {
 
     loop {}
 }
-
-// define what happens in an Out Of Memory (OOM) condition
-#[alloc_error_handler]
-fn alloc_error(_layout: Layout) -> ! {
-    asm::bkpt();
-
-    loop {}
-}

examples/crash.rs

@@ -82,8 +82,10 @@
 use panic_halt as _;
 
 use core::ptr;
+use core::fmt::Write;
 
-use cortex_m_rt::entry;
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+use cortex_m_semihosting::hio;
 
 #[entry]
 fn main() -> ! {
@@ -94,3 +96,12 @@ fn main() -> ! {
 
     loop {}
 }
+
+#[exception(trampoline = true)]
+unsafe fn HardFault(ef: &ExceptionFrame) -> ! {
+    if let Ok(mut hstdout) = hio::hstdout() {
+        writeln!(hstdout, "{:#?}", ef).ok();
+    }
+
+    loop {}
+}

examples/device.rs

@@ -40,7 +40,9 @@ fn main() -> ! {
     let mut syst = p.SYST;
     let mut nvic = p.NVIC;
 
-    nvic.enable(Interrupt::EXTI0);
+    unsafe {
+        nvic.iser[Interrupt::EXTI0 as usize / 32].write(1 << (Interrupt::EXTI0 as usize % 32));
+    }
 
     // configure the system timer to wrap around every second
     syst.set_clock_source(SystClkSource::Core);
@@ -58,5 +60,5 @@ fn main() -> ! {
 
 #[interrupt]
 fn EXTI0() {
-    hprint!(".").unwrap();
+    hprint!(".");
 }

examples/exception.rs

@@ -33,5 +33,5 @@ fn main() -> ! {
 
 #[exception]
 fn SysTick() {
-    hprint!(".").unwrap();
+    hprint!(".");
 }

examples/hello.rs

@@ -10,11 +10,11 @@ use cortex_m_semihosting::{debug, hprintln};
 
 #[entry]
 fn main() -> ! {
-    hprintln!("Hello, world!").unwrap();
+    hprintln!("Hello, world!");
 
     // exit QEMU
     // NOTE do not run this on hardware; it can corrupt OpenOCD state
-    debug::exit(debug::EXIT_SUCCESS);
+    // debug::exit(debug::EXIT_SUCCESS);
 
     loop {}
 }

examples/test_on_host.rs

@@ -28,14 +28,11 @@ use panic_halt as _; // you can put a breakpoint on `rust_begin_unwind` to catch
 // use panic_itm as _; // logs messages over ITM; requires ITM support
 // use panic_semihosting as _; // logs messages to the host stderr; requires a debugger
 
-use cortex_m::asm;
 use cortex_m_rt::entry;
 
 #[cfg(not(test))]
 #[entry]
 fn main() -> ! {
-    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code
-
     loop {
         // your code goes here
     }

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1760423683,
+        "narHash": "sha256-Tb+NYuJhWZieDZUxN6PgglB16yuqBYQeMJyYBGCXlt8=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "a493e93b4a259cd9fea8073f89a7ed9b1c5a1da2",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,48 @@
+# Adapted from https://wiki.nixos.org/wiki/Rust#Installation_via_rustup
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+  outputs =
+    {
+      nixpkgs,
+      flake-utils,
+      ...
+    }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+      in
+      with pkgs;
+      {
+        devShells.default = mkShell {
+          strictDeps = true;
+          nativeBuildInputs = [
+            rustup
+            rustPlatform.bindgenHook
+            rustfmt
+            clippy
+            rust-analyzer
+            pkg-config
+
+            openocd
+            gdb
+            qemu
+            inetutils # telnet for OpenOCD console
+          ];
+          buildInputs = [
+            # Libraries here
+            openssl
+          ];
+          RUSTC_VERSION = "stable";
+          shellHook = ''
+            export PATH="''${RUSTUP_HOME:-~/.rustup}/toolchains/$RUSTC_VERSION-${stdenv.hostPlatform.rust.rustcTarget}/bin:''${CARGO_HOME:-~/.cargo}/bin:$PATH"
+          '';
+        };
+      }
+    );
+}

memory.x

@@ -3,8 +3,8 @@ MEMORY
   /* NOTE 1 K = 1 KiBi = 1024 bytes */
   /* TODO Adjust these memory regions to match your device memory layout */
   /* These values correspond to the LM3S6965, one of the few devices QEMU can emulate */
-  FLASH : ORIGIN = 0x00000000, LENGTH = 256K
-  RAM : ORIGIN = 0x20000000, LENGTH = 64K
+  FLASH : ORIGIN = 0x08000000, LENGTH = 256K
+  RAM : ORIGIN = 0x20000000, LENGTH = 40K
 }
 
 /* This is where the call stack will be allocated. */

openocd.gdb

@@ -36,5 +36,5 @@ monitor arm semihosting enable
 
 load
 
-# start the process but immediately halt the processor
-stepi
+# Run to main
+continue

src/main.rs

@@ -3,18 +3,49 @@
 
 // pick a panicking behavior
 use panic_halt as _; // you can put a breakpoint on `rust_begin_unwind` to catch panics
-// use panic_abort as _; // requires nightly
-// use panic_itm as _; // logs messages over ITM; requires ITM support
-// use panic_semihosting as _; // logs messages to the host stderr; requires a debugger
+                     // use panic_abort as _; // requires nightly
+                     // use panic_itm as _; // logs messages over ITM; requires ITM support
+                     // use panic_semihosting as _; // logs messages to the host stderr; requires a debugger
 
-use cortex_m::asm;
+use cortex_m::peripheral::{syst, Peripherals};
 use cortex_m_rt::entry;
 
+use stm32f3::stm32f303;
+
 #[entry]
 fn main() -> ! {
-    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code
+    let cortex_peripherals = Peripherals::take().unwrap();
+    let mut systick = cortex_peripherals.SYST;
+    systick.set_clock_source(syst::SystClkSource::Core);
+    systick.set_reload(8_000_000); // 1s
+    systick.clear_current();
 
+    let device_peripherals = stm32f303::Peripherals::take().unwrap();
+    let rcc = device_peripherals.RCC;
+    rcc.ahbenr().write(|w| w.iopeen().set_bit());
+    // PE9: LD3 (red)
+    // PE8: LD4 (blue)
+    // PE10: LD5 (orange)
+    let gpioe = device_peripherals.GPIOE;
+    gpioe
+        .moder()
+        .write(|w| w.moder9().output().moder8().output().moder10().output());
+    gpioe.bsrr().write(|w| w.bs9().set_bit());
+    gpioe.bsrr().write(|w| w.bs8().set_bit());
+    gpioe.bsrr().write(|w| w.bs10().set_bit());
+
+    systick.enable_counter();
+    let mut enabled = true;
     loop {
-        // your code goes here
+        while !systick.has_wrapped() {}
+        enabled = !enabled;
+        gpioe.odr().write(|w| {
+            w.odr8()
+                .bit(enabled)
+                .odr9()
+                .bit(enabled)
+                .odr10()
+                .bit(enabled)
+        });
     }
 }