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PWM WS2812B example and per sequence config

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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.
This commit is contained in:
huntc 2022-01-25 18:06:42 +11:00
parent d76cd5ceaf
commit 47aeab152f
4 changed files with 144 additions and 35 deletions
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87
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(),
@ -136,12 +128,28 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
})
}
/// Start or restart playback
/// Start or restart playback. Takes at least one sequence along with its
/// configuration. Optionally takes a second sequence and/or its configuration.
/// In the case where no second sequence is provided then the first sequence
/// is used. In the case where no second sequence configuration is supplied,
/// the first sequence configuration is used. The sequence mode applies to both
/// sequences combined as one.
#[inline(always)]
pub fn start(&mut self, sequence: &'d [u16], times: SequenceMode) -> Result<(), Error> {
slice_in_ram_or(sequence, Error::DMABufferNotInDataMemory)?;
pub fn start(
&mut self,
sequence0: &'d [u16],
sequence_config0: SequenceConfig,
sequence1: Option<&'d [u16]>,
sequence_config1: Option<SequenceConfig>,
times: SequenceMode,
) -> Result<(), Error> {
let alt_sequence = sequence1.unwrap_or(sequence0);
let alt_sequence_config = (&sequence_config1).as_ref().unwrap_or(&sequence_config0);
if sequence.len() > 32767 {
slice_in_ram_or(sequence0, Error::DMABufferNotInDataMemory)?;
slice_in_ram_or(alt_sequence, Error::DMABufferNotInDataMemory)?;
if sequence0.len() > MAX_SEQUENCE_LEN || alt_sequence.len() > MAX_SEQUENCE_LEN {
return Err(Error::SequenceTooLong);
}
@ -153,19 +161,31 @@ impl<'d, T: Instance> SequencePwm<'d, T> {
let r = T::regs();
r.seq0
.refresh
.write(|w| unsafe { w.bits(sequence_config0.refresh) });
r.seq0
.enddelay
.write(|w| unsafe { w.bits(sequence_config0.end_delay) });
r.seq0
.ptr
.write(|w| unsafe { w.bits(sequence.as_ptr() as u32) });
.write(|w| unsafe { w.bits(sequence0.as_ptr() as u32) });
r.seq0
.cnt
.write(|w| unsafe { w.bits(sequence.len() as u32) });
.write(|w| unsafe { w.bits(sequence0.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(sequence.as_ptr() as u32) });
.write(|w| unsafe { w.bits(alt_sequence.as_ptr() as u32) });
r.seq1
.cnt
.write(|w| unsafe { w.bits(sequence.len() as u32) });
.write(|w| unsafe { w.bits(alt_sequence.len() as u32) });
r.enable.write(|w| w.enable().enabled());
@ -356,9 +376,8 @@ impl<'a, T: Instance> Drop for SequencePwm<'a, T> {
}
}
/// Configure an infinite looping sequence for `SequencePwm`
#[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 +386,21 @@ 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,
}
}
}
#[non_exhaustive]
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
@ -376,10 +410,6 @@ 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,
}
@ -389,7 +419,12 @@ impl Default for SequenceConfig {
/// How many times to run the sequence
#[derive(Debug, Eq, PartialEq, Clone, Copy)]
pub enum SequenceMode {
/// Run sequence n Times total
/// Run sequence n Times total.
/// 1 = Run sequence 0 once
/// 2 = Run sequence 0 and then sequence 1
/// 3 to 4 = Run sequence 0, sequence 1, sequence 0 and then sequence 1
/// 5 to 6 = Run sequence 0, sequence 1, sequence 0, sequence 1, sequence 0 and then sequence 1
/// i.e the when >= 2 the loop count is determined by dividing by 2 and rounding up
Times(u16),
/// Repeat until `stop` is called.
Infinite,

23
examples/nrf/src/bin/pwm_sequence.rs
View File

@ -8,7 +8,7 @@ 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, SequenceMode, SequencePwm};
use embassy_nrf::Peripherals;
#[embassy::main]
@ -16,26 +16,39 @@ 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 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 = Config::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);
let _ = pwm.start(
&seq_values_1,
seq_config,
None,
None,
SeqSequenceMode::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 _ = pwm.start(
&seq_values_2,
seq_config,
None,
None,
SequenceMode::Infinite,
);
// 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

9
examples/nrf/src/bin/pwm_sequence_ppi.rs
View File

@ -11,26 +11,27 @@ 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, SequenceMode, SequencePwm};
use embassy_nrf::Peripherals;
#[embassy::main]
async fn main(_spawner: Spawner, p: Peripherals) {
let seq_values: [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));
let _ = pwm.start(&seq_values, seq_config, None, None, SequenceMode::Infinite);
// 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

60
examples/nrf/src/bin/pwm_sequence_ws2812b.rs Normal file
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@ -0,0 +1,60 @@
#![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, SequenceMode, SequencePwm,
};
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
// 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) {
// Declare the bits of 24 bits
let mut blue_seq: [u16; 8 * 3] = [
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
];
let reset_seq = [RES; 1];
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,
));
let blue_seq_config = SequenceConfig::default();
let mut reset_seq_config = SequenceConfig::default();
reset_seq_config.end_delay = 799; // 50us (20 ticks * 40) - 1 tick because we've already got one RES
unwrap!(pwm.start(
&blue_seq,
blue_seq_config,
Some(&reset_seq),
Some(reset_seq_config),
SequenceMode::Times(2)
));
Timer::after(Duration::from_millis(20000)).await;
info!("Program stopped");
}