640: Skip EasyDMA slice location check for empty slices and copy data if necessary r=Dirbaio a=TilBlechschmidt
As discussed, this PR makes the following changes:
- Ignore pointer location of zero-length slices (fixes#631)
- Change default functions so they copy the tx buffer if it does not reside in RAM
- Introduce new variants for `write`, `transfer`, and their blocking versions which fails instead of copying
- Add documentation about the motivation behind all these variants
<img width="984" alt="image" src="https://user-images.githubusercontent.com/5037967/155415788-c2cd1055-9289-4004-959d-be3b1934a439.png">
Remaining TODOs:
- [x] Change copying behaviour for other peripherals
- [x] TWI
- [x] UART
- [x] Add module-level documentation regarding EasyDMA and `_from_ram` method variants
`@Dirbaio` it probably makes sense for you to review it now before I "copy" over the changes to the other two peripherals.
Co-authored-by: Til Blechschmidt <til@blechschmidt.de>
Starting the sampling task prior to starting the SAADC peripheral can lead to unexpected buffer behaviour with multiple channels. We now provide an init callback at the point where the SAADC has started for the first time. This callback can be used to kick off sampling via PPI.
We also need to trigger the SAADC to start sampling the next buffer when the previous one is ended so that we do not drop samples - the major benefit of double buffering.
As a bonus we provide a calibrate method as it is recommended to use before starting up the sampling.
The example has been updated to illustrate these new features.
613: Rust stable support r=Dirbaio a=Dirbaio
This PR adds (limited) stable Rust support!
The drawbacks are:
- No `#[embassy::task]`, `#[embassy::main]`. (requires `type_alias_impl_trait`). You have to manually allocate the tasks somewhere they'll live forever. See [example](https://github.com/embassy-rs/embassy/blob/master/examples/nrf/src/bin/raw_spawn.rs)
- No async trait impls (requires GATs). Note that the full API surface of HALs is still available through inherent methods: #552#581
- Some stuff is not constructible in const (requires `const_fn_trait_bound`), although there's an (ugly) workaround for the generic `Mutex`.
So it's not that bad in the end, it's fully usable for shipping production-ready firmwares. We'll still recommend nightly as the default, until GATs and `type_alias_impl_trait` are stable.
Co-authored-by: Dario Nieuwenhuis <dirbaio@dirbaio.net>
591: PWM WS2812B example and flexible sequence config r=Dirbaio a=huntc
I've permitted the PWM sequences to be mutated on stopping the PWM by associating them with a new `SingleSequencer` structure. This is so that we can perform effects on the LEDs (and other use-cases, I'm sure!). The example has been updated to illustrate the use of this by flashing a WS2812B LED.
There's also a `Sequencer` structure for more sophisticated PWM interactions, along with a `pwm_double_sequence` example to illustrate.
These changes should make it possible to attain all of the nRF PWM functionality available.
Co-authored-by: huntc <huntchr@gmail.com>
This approach owns the sequence buffers which, while introducing an extra move, it eliminates the need to guard the lifetime of the sequence buffer. Given ownership, the buffer will be retained until the PWM sequence task is stopped.
Demonstrates how to set the colour of a WS2812B to blue using PWM, and the use of multiple sequences along with their own config. This required an API change.
I had introduced a small bug in my last PR where I assigned the sequence before stopping the PWM. I now stop the PWM before doing that now.
Also, corrected a math comment.
Sequences are now passed in via the start method to avoid having to stop the PWM and restart it. Sequences continue to be constrained with the same lifetime of the Pwm object itself. The pwm_sequence example has been extended to illustrate multiple sequences being passed around.
This commit allows event_endtx to be used outside of the Uarte itself. As a consequence, PPI can be used to drive tasks given the end of transmission on the Uarte. This is particularly useful for situations like RS485 where a GPIO must be set to high when transmitting then cleared when done. A non-ppi approach can cause a delay in the clearing of this GPIO as other Embassy tasks might become scheduled.
Unsafe is not required here given that all futures are required to live longer than their global peripheral instances. There are other occurrences of unsafe being used on new that should be removed. I started to do that but then went down a bit of a rabbit hole.
539: nrf: async usb r=Dirbaio a=jacobrosenthal
Frankensteined together from this old pr https://github.com/embassy-rs/embassy/pull/115 and nrf-usdb
~Doesnt currently work..~
Co-authored-by: Jacob Rosenthal <jacobrosenthal@gmail.com>
544: Introduces split on the nRF Uarte r=Dirbaio a=huntc
A new `split` method is introduced such that the Uarte tx and rx can be used from separate tasks. An MPSC is used in an example to illustrate how data may be passed between these tasks.
The approach taken within the `Uarte` struct is to split into tx and rx fields on calling `Uarte::new`. These fields are returned given a call to `Uarte::split`, but otherwise, if that call isn't made, then the API remains as it was before.
Here's a snippet from a new example introduced:
```rust
#[embassy::main]
async fn main(spawner: Spawner, p: Peripherals) {
// ...
let uart = uarte::Uarte::new(p.UARTE0, irq, p.P0_08, p.P0_06, NoPin, NoPin, config);
let (mut tx, rx) = uart.split();
// ...
// Spawn a task responsible purely for reading
unwrap!(spawner.spawn(reader(rx, s)));
// ...
// Continue reading in this main task and write
// back out the buffer we receive from the read
// task.
loop {
if let Some(buf) = r.recv().await {
info!("writing...");
unwrap!(tx.write(&buf).await);
}
}
}
#[embassy::task]
async fn reader(mut rx: UarteRx<'static, UARTE0>, s: Sender<'static, Noop, [u8; 8], 1>) {
let mut buf = [0; 8];
loop {
info!("reading...");
unwrap!(rx.read(&mut buf).await);
unwrap!(s.send(buf).await);
}
}
```
Co-authored-by: huntc <huntchr@gmail.com>
A new `split` method is introduced such that the Uarte tx and rx can be used from separate tasks. An MPSC is used to illustrate how data may be passed between these tasks.
