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This commit is contained in:
Ulf Lilleengen 2021-12-10 12:27:44 +01:00
parent b48fcd9229
commit e93f2679b1
3 changed files with 47 additions and 12 deletions
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15
docs/modules/ROOT/pages/basic_application.adoc
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@ -3,8 +3,6 @@
So you've got one of the xref:examples.adoc[examples] running, but what now? Let's go through a simple Embassy application for the nRF52 DK to understand it better.
== The Cargo.toml
== The main
=== Rust Nightly
@ -73,3 +71,16 @@ What happens when the `blinker` task have been spawned and main returns? Well, t
. Runs the executor spawning the main task
There is also a way to run the executor without using the macro, in which case you have to create the `Executor` instance yourself.
== The Cargo.toml
The project definition needs to contain the embassy dependencies:
[source,toml]
----
include::example$examples/nrf/Cargo.toml[lines="9..11"]
----
Depending on your microcontroller, you may need to replace `embassy-nrf` with something else (`embassy-stm32` for STM32. Remember to update feature flags as well).
In this particular case, the nrf52840 chip is selected, and the RTC1 peripheral is used as the time driver.

23
docs/modules/ROOT/pages/stm32.adoc
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@ -1,3 +1,24 @@
= Embassy STM32 HAL
TODO
The link:https://github.com/embassy-rs/embassy/tree/master/embassy-stm32[Embassy STM32 HAL] is based on the `stm32-metapac` project.
== The infinite variant problem
STM32 microcontrollers comes in many families and flavors, and supporting all of them is a big undertaking. Embassy has taken advantage of the fact
that the STM32 peripheral versions are shared across chip families. Instead of re-implementing the SPI
peripheral for every STM32 chip family, embassy have a single SPI implementation that depends on
code-generated register types that are identical for STM32 families with the same version of a given peripheral.
=== The metapac
The `stm32-metapac` module uses pre-generated chip and register definitions for STM32 chip families to generate register types. This is done at compile time based on Cargo feataure flags.
The chip and register definitions are located in a separate module, `stm32-data`, which is modified whenever a bug is found in the definitions, or when adding support for new chip families.
=== The HAL
The `embassy-stm32` module contains the HAL implementation for all STM32 families. The implementation uses automatically derived feature flags to support the correct version of a given peripheral for a given chip family.
== Timer driver
The STM32 timer driver operates at 32768 Hz by default.

21
examples/nrf/src/bin/blinky.rs
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@ -8,18 +8,21 @@ mod example_common;
use defmt::unwrap;
use embassy::executor::Spawner;
use embassy::time::{Duration, Timer};
use embassy_nrf::gpio::{Level, Output, OutputDrive};
use embassy_nrf::Peripherals;
use embassy_nrf::{Peripherals, peripherals::P0_13, gpio::{Level, Output, OutputDrive};
use embedded_hal::digital::v2::OutputPin;
#[embassh::task]
async fn blinker(led: Output<'static, P0_13>, interval: Duration) {
loop {
unwrap!(led.set_high());
Timer::after(interval).await;
unwrap!(led.set_low());
Timer::after(interval).await;
}
}
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let mut led = Output::new(p.P0_13, Level::Low, OutputDrive::Standard);
loop {
unwrap!(led.set_high());
Timer::after(Duration::from_millis(300)).await;
unwrap!(led.set_low());
Timer::after(Duration::from_millis(300)).await;
}
unwrap!(spawner.spawn(blinker(led, Duration::from_millis(300))));
}