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