├── .cargo └── config.toml ├── .dockerignore ├── .github └── workflows │ └── docker-image.yml ├── .gitignore ├── Cargo.toml ├── Dockerfile.ci ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md ├── avr-atmega328p.json ├── examples └── milliseconds.rs ├── rust-toolchain.toml └── src └── lib.rs /.cargo/config.toml: -------------------------------------------------------------------------------- 1 | [unstable] 2 | build-std = [ "core" ] 3 | 4 | [build] 5 | target = "avr-unknown-gnu-atmega328" 6 | -------------------------------------------------------------------------------- /.dockerignore: -------------------------------------------------------------------------------- 1 | target/ 2 | Dockerfile 3 | -------------------------------------------------------------------------------- /.github/workflows/docker-image.yml: -------------------------------------------------------------------------------- 1 | name: Test suite 2 | 3 | on: 4 | push: 5 | branches: [ master ] 6 | pull_request: 7 | branches: [ master ] 8 | schedule: 9 | - cron: "0 2 * * 1-5" 10 | 11 | jobs: 12 | build: 13 | runs-on: ubuntu-latest 14 | 15 | steps: 16 | - uses: actions/checkout@v2 17 | - name: Prepare the AVR Rust build environment 18 | run: 19 | docker build . --file Dockerfile.ci --tag avr-rust/delay.ci:$GITHUB_RUN_NUMBER 20 | 21 | - name: Compile the crate 22 | run: 23 | docker run avr-rust/delay.ci:$GITHUB_RUN_NUMBER 24 | 25 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | /target/ 2 | **/*.rs.bk 3 | Cargo.lock 4 | .vscode/ 5 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "avr_delay" 3 | version = "0.4.2" 4 | authors = ["John Jorgensen "] 5 | edition = "2018" 6 | 7 | description = "A crate for AVR providing software-based delay functions" 8 | repository = "https://github.com/avr-rust/delay" 9 | documentation = "https://docs.rs/avr_delay" 10 | license = "MIT/Apache-2.0" 11 | categories = ["embedded", "no-std", "hardware-support"] 12 | 13 | [dependencies] 14 | avr-config = { version = "2.0", features = ["cpu-frequency"] } 15 | 16 | [dev-dependencies] 17 | avr-std-stub = "1.0" # for examples 18 | -------------------------------------------------------------------------------- /Dockerfile.ci: -------------------------------------------------------------------------------- 1 | FROM ubuntu:18.04 2 | 3 | RUN useradd -m avr-rust 4 | 5 | # Install dependencies 6 | RUN apt-get update -y && apt-get install -y wget gcc binutils gcc-avr avr-libc 7 | 8 | RUN mkdir -p /code && chown avr-rust:avr-rust /code 9 | 10 | USER avr-rust 11 | 12 | # Install Rustup along with nightly 13 | RUN wget -q https://sh.rustup.rs -O /tmp/rustup.sh && sh /tmp/rustup.sh -y --profile minimal --default-toolchain nightly -c rust-src --quiet 14 | ENV PATH=/home/avr-rust/.cargo/bin:$PATH 15 | 16 | COPY --chown=avr-rust:avr-rust . /code/delay 17 | 18 | WORKDIR /code/delay 19 | 20 | ENV AVR_CPU_FREQUENCY_HZ=16000000 21 | 22 | CMD ["cargo", "build", "-Z", "build-std=core", "--target", "avr-unknown-gnu-atmega328", "--release"] 23 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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IN NO EVENT 19 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 20 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 21 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 22 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 23 | DEALINGS IN THE SOFTWARE. 24 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # avr-delay 2 | 3 | 4 | [![Crates.io](https://img.shields.io/crates/v/avr_delay.svg)](https://crates.io/crates/avr_delay) 5 | 6 | [API Documentation](https://docs.rs/avr_delay/) 7 | 8 | The intent of this library is to provide avr specific delay routines similar to the ones provided by the arduino library. The public functions are: 9 | 10 | ## `$AVR_CPU_FREQUENCY_HZ` 11 | 12 | This crate uses the [`avr-config`](https://crates.io/crates/avr-config) crate for fetching the CPU frequency. As such, the `AVR_CPU_FREQUENCY_HZ` environment variable will need to be set when compiling your crate for AVR. 13 | 14 | Example: 15 | 16 | ```bash 17 | export AVR_CPU_FREQUENCY_HZ=16000000 18 | cargo build -Z build-std=core --target avr-unknown-gnu-atmega328 --release 19 | ``` 20 | 21 | ```rust 22 | delay(count: u32) 23 | ``` 24 | 25 | is a raw delay loop. Each loop is 4 cycles. The asm section can loop 65536 times. Initial overhead is about 13 cycles. Each outer loop has an overhead of about 11 cycles. 26 | 27 | ```rust 28 | delay_us(us: u32) 29 | ``` 30 | 31 | delay _us_ microseconds 32 | 33 | ```rust 34 | delay_ms(ms: u32) 35 | ``` 36 | 37 | delay _ms_ milliseconds 38 | 39 | A simple example of how to use it follows. 40 | 41 | Cargo.toml: 42 | 43 | ```toml 44 | [package] 45 | name = "dlyblink" 46 | version = "0.1.0" 47 | authors = ["John Jorgensen"] 48 | 49 | [dependencies] 50 | arduino = "0.1" 51 | avr_delay = { git = "https://github.com/avr-rust/delay" } 52 | ``` 53 | 54 | and your main.rs: 55 | 56 | ```rust 57 | #![feature(asm, lang_items, unwind_attributes)] 58 | 59 | #![no_std] 60 | #![no_main] 61 | 62 | extern crate arduino; 63 | extern crate avr_delay; 64 | 65 | use arduino::{DDRB, PORTB}; 66 | use core::ptr::write_volatile; 67 | use avr_delay::{delay, delay_ms, delay_us}; 68 | 69 | #[no_mangle] 70 | pub extern fn main() { 71 | let mut out: u8 = 0x00; 72 | unsafe { write_volatile(DDRB, 0xff) } 73 | loop { 74 | out = out ^ 0xff; 75 | unsafe { write_volatile(PORTB, out) } 76 | delay_ms(1000000); 77 | } 78 | } 79 | 80 | // These do not need to be in a module, but we group them here for clarity. 81 | pub mod std { 82 | #[lang = "eh_personality"] 83 | #[no_mangle] 84 | pub unsafe extern "C" fn rust_eh_personality(_state: (), _exception_object: *mut (), _context: *mut ()) -> () { 85 | } 86 | 87 | #[lang = "panic_fmt"] 88 | #[unwind] 89 | pub extern fn rust_begin_panic(_msg: (), _file: &'static str, _line: u32) -> ! { 90 | loop { } 91 | } 92 | } 93 | ``` 94 | 95 | No attempt is made to handle arithmetic overruns. 96 | 97 | 98 | ### Internal notes 99 | 100 | #### Cargo publish 101 | 102 | During `cargo publish` there could be 103 | ```text 104 | error: ran out of registers during register allocation 105 | ``` 106 | With that _blocking issue_ is adding `--no-verify` considered 107 | the _lesser evil_ as not releasing. 108 | -------------------------------------------------------------------------------- /avr-atmega328p.json: -------------------------------------------------------------------------------- 1 | { 2 | "arch": "avr", 3 | "cpu": "atmega328p", 4 | "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8", 5 | "env": "", 6 | "executables": true, 7 | "linker": "avr-gcc", 8 | "linker-flavor": "gcc", 9 | "linker-is-gnu": true, 10 | "llvm-target": "avr-unknown-unknown", 11 | "os": "unknown", 12 | "position-independent-executables": false, 13 | "exe-suffix": ".elf", 14 | "eh-frame-header": false, 15 | "pre-link-args": { 16 | "gcc": [ 17 | "-Os", 18 | "-mmcu=atmega328p" 19 | ] 20 | }, 21 | "late-link-args": { 22 | "gcc": [ 23 | "-lc", 24 | "-lgcc" 25 | ] 26 | }, 27 | "target-c-int-width": "16", 28 | "target-endian": "little", 29 | "target-pointer-width": "16", 30 | "vendor": "unknown" 31 | } 32 | -------------------------------------------------------------------------------- /examples/milliseconds.rs: -------------------------------------------------------------------------------- 1 | #![no_std] 2 | #![no_main] 3 | 4 | extern crate avr_std_stub; 5 | 6 | #[no_mangle] 7 | fn main() { 8 | avr_delay::delay_ms(4500); 9 | } 10 | -------------------------------------------------------------------------------- /rust-toolchain.toml: -------------------------------------------------------------------------------- 1 | [toolchain] 2 | channel = "nightly" 3 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | #![feature(asm_experimental_arch)] 2 | #![no_std] 3 | #![crate_name = "avr_delay"] 4 | 5 | use core::arch::asm; 6 | 7 | /// This library is intended to provide a busy-wait delay 8 | /// similar to the one provided by the arduino c++ utilities 9 | /// If you need accurate time keeping you should consider a 10 | /// hardware timer. 11 | 12 | // This library does all of the busy-wait loop in rust. 13 | // We pack as much of the looping as possible into asm! 14 | // so that we can count cycles. 15 | // 16 | // Ignoring the overhead, which may be significant: 17 | // An arduino runs at 16MHZ. Each asm loop is 4 cycles. 18 | // so each loop is 0.25 us. 19 | // 20 | // the overhead of delay() seems to be about 13 cycles 21 | // initially, and then 11 cycles per outer loop. We ignore 22 | // all that. 23 | 24 | /// Internal function to implement a variable busy-wait loop. 25 | /// # Arguments 26 | /// * 'count' - a u64, the number of times to cycle the loop. 27 | #[inline(always)] 28 | pub fn delay(count: u64) { 29 | // Our asm busy-wait takes a 16 bit word as an argument, 30 | // so the max number of loops is 2^16 31 | let outer_count = count / 65536; 32 | let last_count = ((count % 65536) + 1) as u16; 33 | for _ in 0..outer_count { 34 | // Each loop through should be 4 cycles. 35 | let zero = 0u16; 36 | unsafe { 37 | asm!("1: sbiw {i}, 1", 38 | "brne 1b", 39 | i = inout(reg_iw) zero => _, 40 | ) 41 | } 42 | } 43 | unsafe { 44 | asm!("1: sbiw {i}, 1", 45 | "brne 1b", 46 | i = inout(reg_iw) last_count => _, 47 | ) 48 | } 49 | } 50 | 51 | ///delay for N milliseconds 52 | /// # Arguments 53 | /// * 'ms' - an u64, number of milliseconds to busy-wait 54 | #[inline(always)] 55 | pub fn delay_ms(ms: u64) { 56 | // microseconds 57 | let us = ms * 1000; 58 | delay_us(us); 59 | } 60 | 61 | ///delay for N microseconds 62 | /// # Arguments 63 | /// * 'us' - an u64, number of microseconds to busy-wait 64 | #[inline(always)] 65 | pub fn delay_us(us: u64) { 66 | let us_in_loop = (avr_config::CPU_FREQUENCY_HZ / 1000000 / 4) as u64; 67 | let loops = us * us_in_loop; 68 | delay(loops); 69 | } 70 | 71 | #[cfg(test)] 72 | mod tests { 73 | #[test] 74 | fn it_works() { 75 | assert_eq!(2 + 2, 4); 76 | } 77 | } 78 | --------------------------------------------------------------------------------