6179da6b9c
`async fn`s do nothing until polled, but we want the DMA transfer to immediately start in this case. Drivers rely on it. Some require special orders, such as "start DMA, start SPI, then wait for DMA" which is awkward to do without eager start. Also use a manually-impl'd future, this allows getting rid of the "double" Unborrow channel clone. |
||
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.github | ||
.vscode | ||
embassy | ||
embassy-hal-common | ||
embassy-lora | ||
embassy-macros | ||
embassy-net | ||
embassy-nrf | ||
embassy-rp | ||
embassy-stm32 | ||
embassy-traits | ||
examples | ||
stm32-data@3e883bdff7 | ||
stm32-gen-features | ||
stm32-metapac | ||
stm32-metapac-gen | ||
tests/stm32 | ||
xtask | ||
.gitignore | ||
.gitmodules | ||
Cargo.example.toml | ||
ci.sh | ||
LICENSE-APACHE | ||
LICENSE-MIT | ||
README.md | ||
rust-toolchain.toml |
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, essentiallyno_std
compatible versions offutures::io
.embassy::traits::flash
: Flash device trait.embassy::time
:Clock
andAlarm
traits. Std-likeDuration
andInstant
.- 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 implementingAsyncBufRead
andAsyncWrite
. -
qspi
: QSPI driver implementingFlash
. -
gpiote
: GPIOTE driver. Allowsawait
ing 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 implementingClock
andAlarm
, for use withembassy::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 thenrf52840-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 withasync{}
blocks, and forstatic-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
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.