135 lines
4.2 KiB
Rust
135 lines
4.2 KiB
Rust
// Configure TIM3 in PWM mode, and start DMA Transfer(s) to send color data into ws2812.
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// We assume the DIN pin of ws2812 connect to GPIO PB4, and ws2812 is properly powered.
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//
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// This demo is a combination of HAL, PAC, and manually invoke `dma::Transfer`
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//
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// Warning:
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// DO NOT stare at ws2812 directy (especially after each MCU Reset), its (max) brightness could easily make your eyes feel burn.
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#![no_std]
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#![no_main]
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#![feature(type_alias_impl_trait)]
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use embassy_executor::Spawner;
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use embassy_stm32::{
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gpio::OutputType,
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pac,
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time::khz,
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timer::{
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simple_pwm::{PwmPin, SimplePwm},
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Channel, CountingMode,
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},
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};
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use embassy_time::Timer;
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use {defmt_rtt as _, panic_probe as _};
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#[embassy_executor::main]
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async fn main(_spawner: Spawner) {
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let mut device_config = embassy_stm32::Config::default();
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// set SYSCLK/HCLK/PCLK2 to 20 MHz, thus each tick is 0.05 us,
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// and ws2812 timings are integer multiples of 0.05 us
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{
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use embassy_stm32::rcc::*;
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use embassy_stm32::time::*;
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device_config.enable_debug_during_sleep = true;
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device_config.rcc.hse = Some(Hse {
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freq: mhz(12),
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mode: HseMode::Oscillator,
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});
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device_config.rcc.sys = Sysclk::PLL1_P;
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device_config.rcc.pll_src = PllSource::HSE;
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device_config.rcc.pll = Some(Pll {
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prediv: PllPreDiv::DIV6,
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mul: PllMul::MUL80,
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divp: Some(PllPDiv::DIV8),
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divq: None,
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divr: None,
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});
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}
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let mut dp = embassy_stm32::init(device_config);
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let mut ws2812_pwm = SimplePwm::new(
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dp.TIM3,
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Some(PwmPin::new_ch1(dp.PB4, OutputType::PushPull)),
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None,
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None,
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None,
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khz(800), // data rate of ws2812
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CountingMode::EdgeAlignedUp,
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);
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// PAC level hacking,
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// enable auto-reload preload, and enable timer-update-event trigger DMA
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{
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pac::TIM3.cr1().modify(|v| v.set_arpe(true));
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pac::TIM3.dier().modify(|v| v.set_ude(true));
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}
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// construct ws2812 non-return-to-zero (NRZ) code bit by bit
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let max_duty = ws2812_pwm.get_max_duty();
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let n0 = 8 * max_duty / 25; // ws2812 Bit 0 high level timing
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let n1 = 2 * n0; // ws2812 Bit 1 high level timing
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let turn_off = [
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n0, n0, n0, n0, n0, n0, n0, n0, // Green
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n0, n0, n0, n0, n0, n0, n0, n0, // Red
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n0, n0, n0, n0, n0, n0, n0, n0, // Blue
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0, // keep PWM output low after a transfer
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];
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let dim_white = [
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n0, n0, n0, n0, n0, n0, n1, n0, // Green
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n0, n0, n0, n0, n0, n0, n1, n0, // Red
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n0, n0, n0, n0, n0, n0, n1, n0, // Blue
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0, // keep PWM output low after a transfer
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];
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let color_list = [&turn_off, &dim_white];
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// make sure PWM output keep low on first start
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ws2812_pwm.set_duty(Channel::Ch1, 0);
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{
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use embassy_stm32::dma::{Burst, FifoThreshold, Transfer, TransferOptions};
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// configure FIFO and MBURST of DMA, to minimize DMA occupation on AHB/APB
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let mut dma_transfer_option = TransferOptions::default();
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dma_transfer_option.fifo_threshold = Some(FifoThreshold::Full);
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dma_transfer_option.mburst = Burst::Incr8;
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let mut color_list_index = 0;
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loop {
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// start PWM output
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ws2812_pwm.enable(Channel::Ch1);
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unsafe {
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Transfer::new_write(
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// with &mut, we can easily reuse same DMA channel multiple times
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&mut dp.DMA1_CH2,
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5,
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color_list[color_list_index],
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pac::TIM3.ccr(0).as_ptr() as *mut _,
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dma_transfer_option,
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)
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.await;
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// ws2812 need at least 50 us low level input to confirm the input data and change it's state
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Timer::after_micros(50).await;
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}
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// stop PWM output for saving some energy
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ws2812_pwm.disable(Channel::Ch1);
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// wait another half second, so that we can see color change
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Timer::after_millis(500).await;
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// flip the index bit so that next round DMA transfer the other color data
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color_list_index ^= 1;
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}
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}
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}
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