From 47aeab152fff59e64d8244475dfbec338e6f98e5 Mon Sep 17 00:00:00 2001 From: huntc Date: Tue, 25 Jan 2022 18:06:42 +1100 Subject: [PATCH] PWM WS2812B example and per sequence config 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. --- embassy-nrf/src/pwm.rs | 87 ++++++++++++++------ examples/nrf/src/bin/pwm_sequence.rs | 23 ++++-- examples/nrf/src/bin/pwm_sequence_ppi.rs | 9 +- examples/nrf/src/bin/pwm_sequence_ws2812b.rs | 60 ++++++++++++++ 4 files changed, 144 insertions(+), 35 deletions(-) create mode 100644 examples/nrf/src/bin/pwm_sequence_ws2812b.rs diff --git a/embassy-nrf/src/pwm.rs b/embassy-nrf/src/pwm.rs index a77cd633..21b450b1 100644 --- a/embassy-nrf/src/pwm.rs +++ b/embassy-nrf/src/pwm.rs @@ -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 + 'd, ch2: impl Unborrow + 'd, ch3: impl Unborrow + 'd, - config: SequenceConfig, + config: Config, ) -> Result { 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, + 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, diff --git a/examples/nrf/src/bin/pwm_sequence.rs b/examples/nrf/src/bin/pwm_sequence.rs index 56c865d1..2dcbc747 100644 --- a/examples/nrf/src/bin/pwm_sequence.rs +++ b/examples/nrf/src/bin/pwm_sequence.rs @@ -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 diff --git a/examples/nrf/src/bin/pwm_sequence_ppi.rs b/examples/nrf/src/bin/pwm_sequence_ppi.rs index f03c5716..9523671a 100644 --- a/examples/nrf/src/bin/pwm_sequence_ppi.rs +++ b/examples/nrf/src/bin/pwm_sequence_ppi.rs @@ -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 diff --git a/examples/nrf/src/bin/pwm_sequence_ws2812b.rs b/examples/nrf/src/bin/pwm_sequence_ws2812b.rs new file mode 100644 index 00000000..01afd043 --- /dev/null +++ b/examples/nrf/src/bin/pwm_sequence_ws2812b.rs @@ -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"); +}