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Merge #591

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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 commit is contained in:
bors[bot] 2022-02-05 02:20:13 +00:00 committed by GitHub
commit a1d6077446
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GPG key ID: 4AEE18F83AFDEB23
5 changed files with 368 additions and 129 deletions
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335
embassy-nrf/src/pwm.rs
View file

@ -45,6 +45,8 @@ pub enum Error {
DMABufferNotInDataMemory,
}
const MAX_SEQUENCE_LEN: usize = 32767;
impl<'d, T: Instance> SequencePwm<'d, T> {
/// Creates the interface to a `SequencePwm`.
///
@ -62,7 +64,7 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
ch1: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
ch2: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
ch3: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
config: SequenceConfig,
config: Config,
) -> Result<Self, Error> {
unborrow!(ch0, ch1, ch2, ch3);
@ -117,16 +119,6 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
r.countertop
.write(|w| unsafe { w.countertop().bits(config.max_duty) });
r.seq0.refresh.write(|w| unsafe { w.bits(config.refresh) });
r.seq0
.enddelay
.write(|w| unsafe { w.bits(config.end_delay) });
r.seq1.refresh.write(|w| unsafe { w.bits(config.refresh) });
r.seq1
.enddelay
.write(|w| unsafe { w.bits(config.end_delay) });
Ok(Self {
phantom: PhantomData,
ch0: ch0.degrade_optional(),
@ -136,80 +128,6 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
})
}
/// Start or restart playback
#[inline(always)]
pub fn start(&mut self, sequence: &'d [u16], times: SequenceMode) -> Result<(), Error> {
slice_in_ram_or(sequence, Error::DMABufferNotInDataMemory)?;
if sequence.len() > 32767 {
return Err(Error::SequenceTooLong);
}
if let SequenceMode::Times(0) = times {
return Err(Error::SequenceTimesAtLeastOne);
}
self.stop();
let r = T::regs();
r.seq0
.ptr
.write(|w| unsafe { w.bits(sequence.as_ptr() as u32) });
r.seq0
.cnt
.write(|w| unsafe { w.bits(sequence.len() as u32) });
r.seq1
.ptr
.write(|w| unsafe { w.bits(sequence.as_ptr() as u32) });
r.seq1
.cnt
.write(|w| unsafe { w.bits(sequence.len() as u32) });
r.enable.write(|w| w.enable().enabled());
// defensive before seqstart
compiler_fence(Ordering::SeqCst);
match times {
// just the one time, no loop count
SequenceMode::Times(1) => {
r.loop_.write(|w| w.cnt().disabled());
// tasks_seqstart() doesn't exist in all svds so write its bit instead
r.tasks_seqstart[0].write(|w| unsafe { w.bits(0x01) });
}
// loop count is how many times to play BOTH sequences
// 2 total (1 x 2)
// 3 total, (2 x 2) - 1
SequenceMode::Times(n) => {
let odd = n & 1 == 1;
let times = if odd { (n / 2) + 1 } else { n / 2 };
r.loop_.write(|w| unsafe { w.cnt().bits(times) });
// we can subtract 1 by starting at seq1 instead of seq0
if odd {
// tasks_seqstart() doesn't exist in all svds so write its bit instead
r.tasks_seqstart[1].write(|w| unsafe { w.bits(0x01) });
} else {
// tasks_seqstart() doesn't exist in all svds so write its bit instead
r.tasks_seqstart[0].write(|w| unsafe { w.bits(0x01) });
}
}
// to play infinitely, repeat the sequence one time, then have loops done self trigger seq0 again
SequenceMode::Infinite => {
r.loop_.write(|w| unsafe { w.cnt().bits(0x1) });
r.shorts.write(|w| w.loopsdone_seqstart0().enabled());
// tasks_seqstart() doesn't exist in all svds so write its bit instead
r.tasks_seqstart[0].write(|w| unsafe { w.bits(0x01) });
}
}
Ok(())
}
/// Returns reference to `Stopped` event endpoint for PPI.
#[inline(always)]
pub fn event_stopped(&self) -> Event {
@ -309,30 +227,12 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
Task::from_reg(&r.tasks_stop)
}
/// Stop playback. Disables the peripheral. Does NOT clear the last duty
/// cycle from the pin.
#[inline(always)]
pub fn stop(&self) {
let r = T::regs();
r.shorts.reset();
compiler_fence(Ordering::SeqCst);
// tasks_stop() doesn't exist in all svds so write its bit instead
r.tasks_stop.write(|w| unsafe { w.bits(0x01) });
r.enable.write(|w| w.enable().disabled());
}
}
impl<'a, T: Instance> Drop for SequencePwm<'a, T> {
fn drop(&mut self) {
let r = T::regs();
self.stop();
if let Some(pin) = &self.ch0 {
pin.set_low();
pin.conf().reset();
@ -356,9 +256,9 @@ impl<'a, T: Instance> Drop for SequencePwm<'a, T> {
}
}
/// Configure an infinite looping sequence for `SequencePwm`
/// Configuration for the PWM as a whole.
#[non_exhaustive]
pub struct SequenceConfig {
pub struct Config {
/// Selects up mode or up-and-down mode for the counter
pub counter_mode: CounterMode,
/// Top value to be compared against buffer values
@ -367,6 +267,23 @@ pub struct SequenceConfig {
pub prescaler: Prescaler,
/// How a sequence is read from RAM and is spread to the compare register
pub sequence_load: SequenceLoad,
}
impl Default for Config {
fn default() -> Config {
Config {
counter_mode: CounterMode::Up,
max_duty: 1000,
prescaler: Prescaler::Div16,
sequence_load: SequenceLoad::Common,
}
}
}
/// Configuration per sequence
#[non_exhaustive]
#[derive(Clone)]
pub struct SequenceConfig {
/// Number of PWM periods to delay between each sequence sample
pub refresh: u32,
/// Number of PWM periods after the sequence ends before starting the next sequence
@ -376,21 +293,215 @@ pub struct SequenceConfig {
impl Default for SequenceConfig {
fn default() -> SequenceConfig {
SequenceConfig {
counter_mode: CounterMode::Up,
max_duty: 1000,
prescaler: Prescaler::Div16,
sequence_load: SequenceLoad::Common,
refresh: 0,
end_delay: 0,
}
}
}
/// How many times to run the sequence
/// A composition of a sequence buffer and its configuration.
#[non_exhaustive]
pub struct Sequence<'s> {
/// The words comprising the sequence. Must not exceed 32767 words.
pub words: &'s [u16],
/// Configuration associated with the sequence.
pub config: SequenceConfig,
}
impl<'s> Sequence<'s> {
pub fn new(words: &'s [u16], config: SequenceConfig) -> Self {
Self { words, config }
}
}
/// A single sequence that can be started and stopped.
/// Takes at one sequence along with its configuration.
#[non_exhaustive]
pub struct SingleSequencer<'d, 's, T: Instance> {
pub sequencer: Sequencer<'d, 's, T>,
}
impl<'d, 's, T: Instance> SingleSequencer<'d, 's, T> {
/// Create a new sequencer
pub fn new(pwm: &'s mut SequencePwm<'d, T>, words: &'s [u16], config: SequenceConfig) -> Self {
Self {
sequencer: Sequencer::new(pwm, Sequence::new(words, config), None),
}
}
/// Start or restart playback.
#[inline(always)]
pub fn start(&self, times: SingleSequenceMode) -> Result<(), Error> {
let (start_seq, times) = match times {
SingleSequenceMode::Times(n) if n == 1 => (StartSequence::One, SequenceMode::Loop(1)),
SingleSequenceMode::Times(n) if n & 1 == 1 => {
(StartSequence::One, SequenceMode::Loop((n / 2) + 1))
}
SingleSequenceMode::Times(n) => (StartSequence::Zero, SequenceMode::Loop(n / 2)),
SingleSequenceMode::Infinite => (StartSequence::Zero, SequenceMode::Infinite),
};
self.sequencer.start(start_seq, times)
}
/// Stop playback. Disables the peripheral. Does NOT clear the last duty
/// cycle from the pin. Returns any sequences previously provided to
/// `start` so that they may be further mutated.
#[inline(always)]
pub fn stop(&self) {
self.sequencer.stop();
}
}
/// A composition of sequences that can be started and stopped.
/// Takes at least one sequence along with its configuration.
/// Optionally takes a second sequence and its configuration.
/// In the case where no second sequence is provided then the first sequence
/// is used.
#[non_exhaustive]
pub struct Sequencer<'d, 's, T: Instance> {
_pwm: &'s mut SequencePwm<'d, T>,
sequence0: Sequence<'s>,
sequence1: Option<Sequence<'s>>,
}
impl<'d, 's, T: Instance> Sequencer<'d, 's, T> {
/// Create a new double sequence. In the absence of sequence 1, sequence 0
/// will be used twice in the one loop.
pub fn new(
pwm: &'s mut SequencePwm<'d, T>,
sequence0: Sequence<'s>,
sequence1: Option<Sequence<'s>>,
) -> Self {
Sequencer {
_pwm: pwm,
sequence0,
sequence1,
}
}
/// Start or restart playback. The sequence mode applies to both sequences combined as one.
#[inline(always)]
pub fn start(&self, start_seq: StartSequence, times: SequenceMode) -> Result<(), Error> {
let sequence0 = &self.sequence0;
let alt_sequence = self.sequence1.as_ref().unwrap_or(&self.sequence0);
slice_in_ram_or(sequence0.words, Error::DMABufferNotInDataMemory)?;
slice_in_ram_or(alt_sequence.words, Error::DMABufferNotInDataMemory)?;
if sequence0.words.len() > MAX_SEQUENCE_LEN || alt_sequence.words.len() > MAX_SEQUENCE_LEN {
return Err(Error::SequenceTooLong);
}
if let SequenceMode::Loop(0) = times {
return Err(Error::SequenceTimesAtLeastOne);
}
let _ = self.stop();
let r = T::regs();
r.seq0
.refresh
.write(|w| unsafe { w.bits(sequence0.config.refresh) });
r.seq0
.enddelay
.write(|w| unsafe { w.bits(sequence0.config.end_delay) });
r.seq0
.ptr
.write(|w| unsafe { w.bits(sequence0.words.as_ptr() as u32) });
r.seq0
.cnt
.write(|w| unsafe { w.bits(sequence0.words.len() as u32) });
r.seq1
.refresh
.write(|w| unsafe { w.bits(alt_sequence.config.refresh) });
r.seq1
.enddelay
.write(|w| unsafe { w.bits(alt_sequence.config.end_delay) });
r.seq1
.ptr
.write(|w| unsafe { w.bits(alt_sequence.words.as_ptr() as u32) });
r.seq1
.cnt
.write(|w| unsafe { w.bits(alt_sequence.words.len() as u32) });
r.enable.write(|w| w.enable().enabled());
// defensive before seqstart
compiler_fence(Ordering::SeqCst);
let seqstart_index = if start_seq == StartSequence::One {
1
} else {
0
};
match times {
// just the one time, no loop count
SequenceMode::Loop(n) => {
r.loop_.write(|w| unsafe { w.cnt().bits(n) });
}
// to play infinitely, repeat the sequence one time, then have loops done self trigger seq0 again
SequenceMode::Infinite => {
r.loop_.write(|w| unsafe { w.cnt().bits(0x1) });
r.shorts.write(|w| w.loopsdone_seqstart0().enabled());
}
}
// tasks_seqstart() doesn't exist in all svds so write its bit instead
r.tasks_seqstart[seqstart_index].write(|w| unsafe { w.bits(0x01) });
Ok(())
}
/// Stop playback. Disables the peripheral. Does NOT clear the last duty
/// cycle from the pin. Returns any sequences previously provided to
/// `start` so that they may be further mutated.
#[inline(always)]
pub fn stop(&self) {
let r = T::regs();
r.shorts.reset();
compiler_fence(Ordering::SeqCst);
// tasks_stop() doesn't exist in all svds so write its bit instead
r.tasks_stop.write(|w| unsafe { w.bits(0x01) });
r.enable.write(|w| w.enable().disabled());
}
}
impl<'d, 's, T: Instance> Drop for Sequencer<'d, 's, T> {
fn drop(&mut self) {
let _ = self.stop();
}
}
/// How many times to run a single sequence
#[derive(Debug, Eq, PartialEq, Clone, Copy)]
pub enum SingleSequenceMode {
/// Run a single sequence n Times total.
Times(u16),
/// Repeat until `stop` is called.
Infinite,
}
/// Which sequence to start a loop with
#[derive(Debug, Eq, PartialEq, Clone, Copy)]
pub enum StartSequence {
/// Start with Sequence 0
Zero,
/// Start with Sequence 1
One,
}
/// How many loops to run two sequences
#[derive(Debug, Eq, PartialEq, Clone, Copy)]
pub enum SequenceMode {
/// Run sequence n Times total
Times(u16),
/// Run two sequences n loops i.e. (n * (seq0 + seq1.unwrap_or(seq0)))
Loop(u16),
/// Repeat until `stop` is called.
Infinite,
}

46
examples/nrf/src/bin/pwm_double_sequence.rs Normal file
View file

@ -0,0 +1,46 @@
#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]
#[path = "../example_common.rs"]
mod example_common;
use defmt::*;
use embassy::executor::Spawner;
use embassy::time::{Duration, Timer};
use embassy_nrf::gpio::NoPin;
use embassy_nrf::pwm::{
Config, Prescaler, Sequence, SequenceConfig, SequenceMode, SequencePwm, Sequencer,
StartSequence,
};
use embassy_nrf::Peripherals;
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let seq_words_0: [u16; 5] = [1000, 250, 100, 50, 0];
let seq_words_1: [u16; 4] = [50, 100, 250, 1000];
let mut config = Config::default();
config.prescaler = Prescaler::Div128;
// 1 period is 1000 * (128/16mhz = 0.000008s = 0.008ms) = 8us
// but say we want to hold the value for 5000ms
// so we want to repeat our value as many times as necessary until 5000ms passes
// want 5000/8 = 625 periods total to occur, so 624 (we get the one period for free remember)
let mut seq_config = SequenceConfig::default();
seq_config.refresh = 624;
// thus our sequence takes 5 * 5000ms or 25 seconds
let mut pwm = unwrap!(SequencePwm::new(
p.PWM0, p.P0_13, NoPin, NoPin, NoPin, config,
));
let sequence_0 = Sequence::new(&seq_words_0, seq_config.clone());
let sequence_1 = Sequence::new(&seq_words_1, seq_config);
let sequencer = Sequencer::new(&mut pwm, sequence_0, Some(sequence_1));
unwrap!(sequencer.start(StartSequence::Zero, SequenceMode::Loop(1)));
// we can abort a sequence if we need to before its complete with pwm.stop()
// or stop is also implicitly called when the pwm peripheral is dropped
// when it goes out of scope
Timer::after(Duration::from_millis(40000)).await;
info!("pwm stopped early!");
}

21
examples/nrf/src/bin/pwm_sequence.rs
View file

@ -8,34 +8,31 @@ use defmt::*;
use embassy::executor::Spawner;
use embassy::time::{Duration, Timer};
use embassy_nrf::gpio::NoPin;
use embassy_nrf::pwm::{Prescaler, SequenceConfig, SequenceMode, SequencePwm};
use embassy_nrf::pwm::{
Config, Prescaler, SequenceConfig, SequencePwm, SingleSequenceMode, SingleSequencer,
};
use embassy_nrf::Peripherals;
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let seq_values_1: [u16; 5] = [1000, 250, 100, 50, 0];
let seq_values_2: [u16; 5] = [0, 50, 100, 250, 1000];
let seq_words: [u16; 5] = [1000, 250, 100, 50, 0];
let mut config = SequenceConfig::default();
let mut config = Config::default();
config.prescaler = Prescaler::Div128;
// 1 period is 1000 * (128/16mhz = 0.000008s = 0.008ms) = 8us
// but say we want to hold the value for 5000ms
// so we want to repeat our value as many times as necessary until 5000ms passes
// want 5000/8 = 625 periods total to occur, so 624 (we get the one period for free remember)
config.refresh = 624;
let mut seq_config = SequenceConfig::default();
seq_config.refresh = 624;
// thus our sequence takes 5 * 5000ms or 25 seconds
let mut pwm = unwrap!(SequencePwm::new(
p.PWM0, p.P0_13, NoPin, NoPin, NoPin, config,
));
let _ = pwm.start(&seq_values_1, SequenceMode::Infinite);
info!("pwm started!");
Timer::after(Duration::from_millis(20000)).await;
info!("pwm starting with another sequence!");
let _ = pwm.start(&seq_values_2, SequenceMode::Infinite);
let sequencer = SingleSequencer::new(&mut pwm, &seq_words, seq_config);
unwrap!(sequencer.start(SingleSequenceMode::Times(1)));
// we can abort a sequence if we need to before its complete with pwm.stop()
// or stop is also implicitly called when the pwm peripheral is dropped

15
examples/nrf/src/bin/pwm_sequence_ppi.rs
View file

@ -11,26 +11,28 @@ use embassy::executor::Spawner;
use embassy_nrf::gpio::{Input, NoPin, Pull};
use embassy_nrf::gpiote::{InputChannel, InputChannelPolarity};
use embassy_nrf::ppi::Ppi;
use embassy_nrf::pwm::{Prescaler, SequenceConfig, SequenceMode, SequencePwm};
use embassy_nrf::pwm::{
Config, Prescaler, SequenceConfig, SequencePwm, SingleSequenceMode, SingleSequencer,
};
use embassy_nrf::Peripherals;
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let seq_values: [u16; 5] = [1000, 250, 100, 50, 0];
let seq_words: [u16; 5] = [1000, 250, 100, 50, 0];
let mut config = SequenceConfig::default();
let mut config = Config::default();
config.prescaler = Prescaler::Div128;
// 1 period is 1000 * (128/16mhz = 0.000008s = 0.008ms) = 8us
// but say we want to hold the value for 250ms 250ms/8 = 31.25 periods
// so round to 31 - 1 (we get the one period for free remember)
// thus our sequence takes 5 * 250ms or 1.25 seconds
config.refresh = 30;
let mut seq_config = SequenceConfig::default();
seq_config.refresh = 30;
let mut pwm = unwrap!(SequencePwm::new(
p.PWM0, p.P0_13, NoPin, NoPin, NoPin, config,
));
let _ = pwm.start(&seq_values, SequenceMode::Times(1));
// pwm.stop() deconfigures pins, and then the task_start_seq0 task cant work
// so its going to have to start running in order load the configuration
@ -51,6 +53,9 @@ async fn main(_spawner: Spawner, p: Peripherals) {
let start = unsafe { pwm.task_start_seq0() };
let stop = unsafe { pwm.task_stop() };
let sequencer = SingleSequencer::new(&mut pwm, &seq_words, seq_config);
unwrap!(sequencer.start(SingleSequenceMode::Infinite));
let mut ppi = Ppi::new_one_to_one(p.PPI_CH1, button1.event_in(), start);
ppi.enable();

80
examples/nrf/src/bin/pwm_sequence_ws2812b.rs Normal file
View file

@ -0,0 +1,80 @@
#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]
#[path = "../example_common.rs"]
mod example_common;
use defmt::*;
use embassy::executor::Spawner;
use embassy::time::{Duration, Timer};
use embassy_nrf::gpio::NoPin;
use embassy_nrf::pwm::{
Config, Prescaler, SequenceConfig, SequenceLoad, SequencePwm, SingleSequenceMode,
SingleSequencer,
};
use embassy_nrf::Peripherals;
// WS2812B LED light demonstration. Drives just one light.
// The following reference on WS2812B may be of use:
// https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf.
// This demo lights up a single LED in blue. It then proceeds
// to pulsate the LED rapidly.
// In the following declarations, setting the high bit tells the PWM
// to reverse polarity, which is what the WS2812B expects.
const T1H: u16 = 0x8000 | 13; // Duty = 13/20 ticks (0.8us/1.25us) for a 1
const T0H: u16 = 0x8000 | 7; // Duty 7/20 ticks (0.4us/1.25us) for a 0
const RES: u16 = 0x8000;
// Provides data to a WS2812b (Neopixel) LED and makes it go blue. The data
// line is assumed to be P1_05.
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let mut config = Config::default();
config.sequence_load = SequenceLoad::Common;
config.prescaler = Prescaler::Div1;
config.max_duty = 20; // 1.25us (1s / 16Mhz * 20)
let mut pwm = unwrap!(SequencePwm::new(
p.PWM0, p.P1_05, NoPin, NoPin, NoPin, config,
));
// Declare the bits of 24 bits in a buffer we'll be
// mutating later.
let mut seq_words = [
T0H, T0H, T0H, T0H, T0H, T0H, T0H, T0H, // G
T0H, T0H, T0H, T0H, T0H, T0H, T0H, T0H, // R
T1H, T1H, T1H, T1H, T1H, T1H, T1H, T1H, // B
RES,
];
let mut seq_config = SequenceConfig::default();
seq_config.end_delay = 799; // 50us (20 ticks * 40) - 1 tick because we've already got one RES;
let mut color_bit = 16;
let mut bit_value = T0H;
loop {
let sequences = SingleSequencer::new(&mut pwm, &seq_words, seq_config.clone());
unwrap!(sequences.start(SingleSequenceMode::Times(1)));
Timer::after(Duration::from_millis(50)).await;
if bit_value == T0H {
if color_bit == 20 {
bit_value = T1H;
} else {
color_bit += 1;
}
} else {
if color_bit == 16 {
bit_value = T0H;
} else {
color_bit -= 1;
}
}
drop(sequences);
seq_words[color_bit] = bit_value;
}
}