avr-delay

API Documentation

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:

NOTE: This library currently hardcodes the microcontroller frequency to 16MHz. This will not always be correct. See avr-rust/delay#2 for more details.

rust delay(count: u32)

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.

rust delay_us(us: u32)

delay us microseconds

rust delay_ms(ms: u32)

delay ms milliseconds

A simple example of how to use it follows.

Cargo.toml:

```toml [package] name = "dlyblink" version = "0.1.0" authors = ["John Jorgensen"]

[dependencies]
arduino = "0.1"
avr_delay = { git = "https://github.com/avr-rust/delay" }

```

and your main.rs:

```rust

![feature(asm, langitems, unwindattributes)]

![no_std]

![no_main]

extern crate arduino; extern crate avr_delay;

use arduino::{DDRB, PORTB}; use core::ptr::writevolatile; use avrdelay::{delay, delayms, delayus};

[no_mangle]

pub extern fn main() { let mut out: u8 = 0x00; unsafe { writevolatile(DDRB, 0xff) } loop { out = out ^ 0xff; unsafe { writevolatile(PORTB, out) } delay_ms(1000000); } }

// These do not need to be in a module, but we group them here for clarity. pub mod std { #[lang = "ehpersonality"] #[nomangle] pub unsafe extern "C" fn rustehpersonality(state: (), _exceptionobject: *mut (), _context: *mut ()) -> () { }

#[lang = "panic_fmt"]
#[unwind]
pub extern fn rust_begin_panic(_msg: (), _file: &'static str, _line: u32) -> ! {
    loop { }
}

} ```

No attempt is made to handle arithmetic overruns.