79 lines
2.4 KiB
Rust
79 lines
2.4 KiB
Rust
#![no_std]
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#![no_main]
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#![feature(type_alias_impl_trait)]
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use defmt::*;
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use embassy::executor::Spawner;
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use embassy::time::{Duration, Timer};
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use embassy_nrf::pwm::{
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Config, Prescaler, SequenceConfig, SequenceLoad, SequencePwm, SingleSequenceMode,
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SingleSequencer,
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};
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use embassy_nrf::Peripherals;
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use defmt_rtt as _; // global logger
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use panic_probe as _;
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// WS2812B LED light demonstration. Drives just one light.
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// The following reference on WS2812B may be of use:
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// https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf.
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// This demo lights up a single LED in blue. It then proceeds
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// to pulsate the LED rapidly.
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// In the following declarations, setting the high bit tells the PWM
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// to reverse polarity, which is what the WS2812B expects.
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const T1H: u16 = 0x8000 | 13; // Duty = 13/20 ticks (0.8us/1.25us) for a 1
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const T0H: u16 = 0x8000 | 7; // Duty 7/20 ticks (0.4us/1.25us) for a 0
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const RES: u16 = 0x8000;
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// Provides data to a WS2812b (Neopixel) LED and makes it go blue. The data
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// line is assumed to be P1_05.
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#[embassy::main]
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async fn main(_spawner: Spawner, p: Peripherals) {
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let mut config = Config::default();
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config.sequence_load = SequenceLoad::Common;
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config.prescaler = Prescaler::Div1;
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config.max_duty = 20; // 1.25us (1s / 16Mhz * 20)
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let mut pwm = unwrap!(SequencePwm::new_1ch(p.PWM0, p.P1_05, config));
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// Declare the bits of 24 bits in a buffer we'll be
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// mutating later.
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let mut seq_words = [
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T0H, T0H, T0H, T0H, T0H, T0H, T0H, T0H, // G
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T0H, T0H, T0H, T0H, T0H, T0H, T0H, T0H, // R
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T1H, T1H, T1H, T1H, T1H, T1H, T1H, T1H, // B
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RES,
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];
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let mut seq_config = SequenceConfig::default();
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seq_config.end_delay = 799; // 50us (20 ticks * 40) - 1 tick because we've already got one RES;
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let mut color_bit = 16;
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let mut bit_value = T0H;
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loop {
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let sequences = SingleSequencer::new(&mut pwm, &seq_words, seq_config.clone());
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unwrap!(sequences.start(SingleSequenceMode::Times(1)));
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Timer::after(Duration::from_millis(50)).await;
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if bit_value == T0H {
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if color_bit == 20 {
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bit_value = T1H;
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} else {
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color_bit += 1;
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}
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} else {
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if color_bit == 16 {
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bit_value = T0H;
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} else {
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color_bit -= 1;
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}
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}
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drop(sequences);
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seq_words[color_bit] = bit_value;
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}
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}
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