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Modern embedded framework, using Rust and async.
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Merge #425 
425: Implements continuous sampling for the nRF SAADC r=huntc a=huntc

Implements continuous sampling for the nRF SAADC and also renames `OneShot` to `Saadc`. The one-shot behaviour is retained with the `sample` method and a new `run_sampler` method is provided for efficiently (i.e. zero copying) sampler processing. A double buffer is used for continuously sampling, which is swapped appropriately.

A sample frequency is provided and will set the internal timer of the SAADC when there is just one channel being sampled. Otherwise, PPI will be used to hook up the TIMER peripheral to drive the sampling task. Two methods are provided for this: `run_task_sampler` and `run_task_sampler` with the latter available where the compiler sees that just one channel is configured. Note that we set up the PPI and timer behaviour outside of the `Saadc` for maximum flexibility.

A callback is provided to the `run_sampler` method. This is a synchronous callback that should return in a reasonably short space of time. The SAADC could stall if it does not. A reasonable practice is to perform a small amount of processing within the callback to yield a signal, perhaps via `mpsc`. In the case of `mpsc`, the `try_send` method becomes useful.

A new example has been provided to illustrate continuous sampling, along with multiple channels and external timing:

```rust
#[embassy::main]
async fn main(_spawner: Spawner, mut p: Peripherals) {
    let config = Config::default();
    let channel_1_config = ChannelConfig::single_ended(&mut p.P0_02);
    let channel_2_config = ChannelConfig::single_ended(&mut p.P0_03);
    let channel_3_config = ChannelConfig::single_ended(&mut p.P0_04);
    let mut saadc = Saadc::new(
        p.SAADC,
        interrupt::take!(SAADC),
        config,
        [channel_1_config, channel_2_config, channel_3_config],
    );

    let mut timer = Timer::new(p.TIMER0);
    timer.set_frequency(Frequency::F1MHz);
    timer.cc(0).write(100); // We want to sample at 10KHz
    timer.cc(0).short_compare_clear();

    let mut ppi = Ppi::new(p.PPI_CH0);
    ppi.set_event(timer.cc(0).event_compare());
    ppi.set_task(saadc.task_sample());
    ppi.enable();

    timer.start();

    let mut bufs = [[[0; 3]; 50]; 2];

    let mut c = 0;
    let mut a: i32 = 0;

    saadc
        .run_task_sampler(&mut bufs, move |buf| {
            for b in buf {
                a += b[0] as i32;
            }
            c += buf.len();
            if c > 10000 {
                a = a / c as i32;
                info!("channel 1: {=i32}", a);
                c = 0;
                a = 0;
            }
            SamplerState::Sampled
        })
        .await;
}
```

Co-authored-by: huntc <huntchr@gmail.com>
2021-10-18 00:51:19 +00:00
.github Merge #423 2021-10-13 21:11:41 +00:00
.vscode Clippy fixes 2021-10-18 01:05:29 +02:00
embassy Clippy fixes 2021-10-18 01:05:29 +02:00
embassy-hal-common Clippy fixes 2021-10-18 01:05:29 +02:00
embassy-lora Update to newer revision of async lorawan stack 2021-10-11 13:51:00 +02:00
embassy-macros Clippy fixes 2021-10-18 01:05:29 +02:00
embassy-net Clippy fixes 2021-10-18 01:05:29 +02:00
embassy-nrf Comments corrected 2021-10-18 11:45:23 +11:00
embassy-rp Update version of critical-section 2021-09-13 17:05:17 +02:00
embassy-stm32 inline FRE register check for SPI on F1 2021-10-11 23:33:32 +02:00
embassy-traits Clippy fixes 2021-10-18 01:05:29 +02:00
examples Merge #425 2021-10-18 00:51:19 +00:00
stm32-data@bae2d34445 feat: Add spi support for STM32F1 variants 2021-10-11 22:39:48 +02:00
stm32-gen-features Initial STM32F1 family support with two examples for STM32F103C8 (Blue Pill) 2021-09-28 18:31:04 +02:00
stm32-metapac Support for STM32L1 2021-09-21 14:50:23 +02:00
stm32-metapac-gen Support for STM32L1 2021-09-21 14:50:23 +02:00
xtask Update lots of deps 2021-09-11 01:35:23 +02:00
.gitignore Update lots of deps 2021-09-11 01:35:23 +02:00
.gitmodules Add stm32-metapac crate, with codegen in rust 2021-05-31 02:40:58 +02:00
Cargo.example.toml std: fold into embassy core, add non-hacky time driver. 2021-08-25 21:06:27 +02:00
LICENSE-APACHE First commit 2020-09-22 18:03:43 +02:00
LICENSE-MIT First commit 2020-09-22 18:03:43 +02:00
README.md Extend SAADC one shot support 2021-10-09 11:25:18 +11:00
rust-toolchain.toml Update nightly 2021-10-18 01:26:06 +02:00

README.md

Embassy

Embassy is a project to make async/await a first-class option for embedded development. For more information and instructions to get started, click here.

Traits and types

embassy provides a set of traits and types specifically designed for async usage.

  • embassy::io: AsyncBufRead, AsyncWrite. Traits for byte-stream IO, essentially no_std compatible versions of futures::io.
  • embassy::traits::flash: Flash device trait.
  • embassy::time: Clock and Alarm traits. Std-like Duration and Instant.
  • More traits for SPI, I2C, UART async HAL coming soon.

Executor

The embassy::executor module provides an async/await executor designed for embedded usage.

  • No alloc, no heap needed. Task futures are statically allocated.
  • No "fixed capacity" data structures, executor works with 1 or 1000 tasks without needing config/tuning.
  • Integrated timer queue: sleeping is easy, just do Timer::after(Duration::from_secs(1)).await;.
  • No busy-loop polling: CPU sleeps when there's no work to do, using interrupts or WFE/SEV.
  • Efficient polling: a wake will only poll the woken task, not all of them.
  • Fair: a task can't monopolize CPU time even if it's constantly being woken. All other tasks get a chance to run before a given task gets polled for the second time.
  • Creating multiple executor instances is supported, to run tasks with multiple priority levels. This allows higher-priority tasks to preempt lower-priority tasks.

Utils

embassy::util contains some lightweight async/await utilities, mainly helpful for async driver development (signaling a task that an interrupt has occured, for example).

embassy-nrf

The embassy-nrf crate contains implementations for nRF 52 series SoCs.

  • uarte: UARTE driver implementing AsyncBufRead and AsyncWrite.

  • qspi: QSPI driver implementing Flash.

  • gpiote: GPIOTE driver. Allows awaiting GPIO pin changes. Great for reading buttons or receiving interrupts from external chips.

  • saadc: SAADC driver. Provides a full implementation of the one-shot sampling for analog channels.

  • rtc: RTC driver implementing Clock and Alarm, for use with embassy::executor.

Examples

Examples are found in the examples/ folder seperated by the chip manufacturer they are designed to run on:

  • examples/nrf are designed to run on the nrf52840-dk board (PCA10056) but should be easily adaptable to other nRF52 chips and boards.
  • examples/rp are for the RP2040 chip.
  • examples/stm32 are designed for the STM32F429ZI chip but should be easily adaptable to other STM32F4xx chips.
  • examples/std are designed to run locally on your pc.

Running examples

  • Setup git submodules (needed for STM32 examples)
git submodule init
git submodule update
  • Install probe-run with defmt support.
cargo install probe-run
  • Run the example
cargo run --bin rtc_async

Minimum supported Rust version (MSRV)

Required nightly version is specified in the rust-toolchain.toml file. Nightly is required for:

  • generic_associated_types: for trait funcs returning futures.
  • type_alias_impl_trait: for trait funcs returning futures implemented with async{} blocks, and for static-executor.

Stable support is a non-goal until these features get stabilized.

Why the name?

EMBedded ASYnc! :)

License

This work is licensed under either of

at your option.