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Modern embedded framework, using Rust and async.
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Dario Nieuwenhuis b1240217bd Remove Portal. Fixes #32 
Portal is very niche, I've only ever used it in `nrf-softdevice` and in a very particular case:
sending event raw-pointers across tasks but "synchronously", because the destination task must process
it now, so it's not deallocated. For most usecases, Signal or channels is enough.

It's unclear to me whether it can be made ub-free. It has problems with reentrancy. It's also not leak-safe, which is quite annoying.

So, remove it for now. We can always add it back later.
2021-08-05 22:24:03 +02:00
.github/workflows time: replace dyn clock/alarm with a global Driver trait 2021-08-05 19:14:09 +02:00
.vscode Update vscode settings. 2021-07-16 14:41:20 -04:00
embassy Remove Portal. Fixes #32 2021-08-05 22:24:03 +02:00
embassy-hal-common common: Initialize PeripheralMutex state with closure to ensure it's done in-place. 2021-08-02 20:13:41 +02:00
embassy-macros time: replace dyn clock/alarm with a global Driver trait 2021-08-05 19:14:09 +02:00
embassy-net net: Make the user pass in the StackResources in init 2021-06-20 17:15:18 -03:00
embassy-nrf time_driver: use regular fn ptr -> raw ptr casts 2021-08-05 19:19:47 +02:00
embassy-rp time: replace dyn clock/alarm with a global Driver trait 2021-08-05 19:14:09 +02:00
embassy-std time: replace dyn clock/alarm with a global Driver trait 2021-08-05 19:14:09 +02:00
embassy-stm32 time_driver: use regular fn ptr -> raw ptr casts 2021-08-05 19:19:47 +02:00
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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.
  • 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.