From 47aeab152fff59e64d8244475dfbec338e6f98e5 Mon Sep 17 00:00:00 2001 From: huntc Date: Tue, 25 Jan 2022 18:06:42 +1100 Subject: 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. --- 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 ++++++++++++++++++++++++++++ 3 files changed, 83 insertions(+), 9 deletions(-) create mode 100644 examples/nrf/src/bin/pwm_sequence_ws2812b.rs (limited to 'examples') diff --git a/examples/nrf/src/bin/pwm_sequence.rs b/examples/nrf/src/bin/pwm_sequence.rs index 56c865d1c..2dcbc7475 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 f03c5716a..9523671a4 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 000000000..01afd043b --- /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"); +} -- cgit