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Modern embedded framework, using Rust and async.
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Liam Murphy 079526559f Remove critical sections from PeripheralMutex interrupt handler by checking the interrupt's priority on startup. 
Since `PeripheralMutex` is the only way to safely maintain state across interrupts, and it no longer allows setting the interrupt's priority, the priority changing isn't a concern.

This also prevents other causes of UB due to the interrupt being exposed during `with`, and allowing enabling the interrupt and setting its context to a bogus pointer.
2021-07-27 17:28:52 +10:00
.github/workflows Deny warnings in CI 2021-07-05 02:44:12 +02:00
.vscode rp: clock setup 2021-06-25 03:38:21 +02:00
embassy Add Send/Sync bounds to PeripheralState 2021-07-24 12:53:57 +10:00
embassy-extras Remove critical sections from PeripheralMutex interrupt handler by checking the interrupt's priority on startup. 2021-07-27 17:28:52 +10:00
embassy-macros STM: Change embassy main to use TIM3 instead of TIM2 2021-07-04 15:51:10 -03:00
embassy-net net: Make the user pass in the StackResources in init 2021-06-20 17:15:18 -03:00
embassy-nrf Remove critical sections from PeripheralMutex interrupt handler by checking the interrupt's priority on startup. 2021-07-27 17:28:52 +10:00
embassy-rp Fix warnings in std and rp 2021-07-04 12:46:04 +10:00
embassy-std Add std version of embassy::main 2021-04-12 14:14:03 +02:00
embassy-stm32 Remove critical sections from PeripheralMutex interrupt handler by checking the interrupt's priority on startup. 2021-07-27 17:28:52 +10:00
embassy-traits nrf async twim 2021-06-04 17:31:35 +02:00
examples stm32/adc: simplify delay handling 2021-07-05 03:18:23 +02:00
stm32-data@409ed5502c F0: Fix missing apb2 clock 2021-07-03 02:12:22 -03:00
stm32-metapac Add USARTv3 support. 2021-07-01 11:30:54 -04:00
.gitignore Merge remote-tracking branch 'embassy-net/main' 2021-05-28 23:07:27 +02:00
.gitmodules Add stm32-metapac crate, with codegen in rust 2021-05-31 02:40:58 +02:00
Cargo.example.toml rp: clock setup 2021-06-25 03:38:21 +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 Improve examples section of readme 2021-06-05 13:34:44 +10:00
rust-toolchain.toml Initial support and example for STM32WB55 2021-06-12 07:06:36 +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.
  • 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.