From a165d73eedfd7e02fe5360e9d844882e0d0df113 Mon Sep 17 00:00:00 2001 From: eZio Pan Date: Fri, 15 Dec 2023 14:10:11 +0800 Subject: [PATCH 1/3] add ws2812 example for stm32f4 with PWM and DMA --- examples/stm32f4/src/bin/ws2812_pwm_dma.rs | 135 +++++++++++++++++++++ 1 file changed, 135 insertions(+) create mode 100644 examples/stm32f4/src/bin/ws2812_pwm_dma.rs diff --git a/examples/stm32f4/src/bin/ws2812_pwm_dma.rs b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs new file mode 100644 index 00000000..79493dce --- /dev/null +++ b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs @@ -0,0 +1,135 @@ +// 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, + pac, + time::khz, + timer::{ + simple_pwm::{PwmPin, SimplePwm}, + 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]; + + // make sure PWM output keep low on first start + ws2812_pwm.set_duty(Channel::Ch1, 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(Channel::Ch1); + + 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(0).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(Channel::Ch1); + + // 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; + } + } +} From 77e372e842c64b95e94fff93a711112514588841 Mon Sep 17 00:00:00 2001 From: eZio Pan Date: Fri, 15 Dec 2023 14:15:45 +0800 Subject: [PATCH 2/3] cargo fmt --- examples/stm32f4/src/bin/ws2812_pwm_dma.rs | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) diff --git a/examples/stm32f4/src/bin/ws2812_pwm_dma.rs b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs index 79493dce..0c3444a4 100644 --- a/examples/stm32f4/src/bin/ws2812_pwm_dma.rs +++ b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs @@ -11,18 +11,12 @@ #![feature(type_alias_impl_trait)] use embassy_executor::Spawner; - -use embassy_stm32::{ - gpio::OutputType, - pac, - time::khz, - timer::{ - simple_pwm::{PwmPin, SimplePwm}, - Channel, CountingMode, - }, -}; +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] From ea1e1973eb88a3a57e7f4e2ad97d32e5fcd8b8d1 Mon Sep 17 00:00:00 2001 From: eZio Pan Date: Sat, 16 Dec 2023 02:15:56 +0800 Subject: [PATCH 3/3] unify channel assign --- examples/stm32f4/src/bin/ws2812_pwm_dma.rs | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/examples/stm32f4/src/bin/ws2812_pwm_dma.rs b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs index 0c3444a4..52cc665c 100644 --- a/examples/stm32f4/src/bin/ws2812_pwm_dma.rs +++ b/examples/stm32f4/src/bin/ws2812_pwm_dma.rs @@ -85,8 +85,10 @@ async fn main(_spawner: Spawner) { 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(Channel::Ch1, 0); + ws2812_pwm.set_duty(pwm_channel, 0); { use embassy_stm32::dma::{Burst, FifoThreshold, Transfer, TransferOptions}; @@ -100,7 +102,7 @@ async fn main(_spawner: Spawner) { loop { // start PWM output - ws2812_pwm.enable(Channel::Ch1); + ws2812_pwm.enable(pwm_channel); unsafe { Transfer::new_write( @@ -108,7 +110,7 @@ async fn main(_spawner: Spawner) { &mut dp.DMA1_CH2, 5, color_list[color_list_index], - pac::TIM3.ccr(0).as_ptr() as *mut _, + pac::TIM3.ccr(pwm_channel.raw()).as_ptr() as *mut _, dma_transfer_option, ) .await; @@ -117,7 +119,7 @@ async fn main(_spawner: Spawner) { } // stop PWM output for saving some energy - ws2812_pwm.disable(Channel::Ch1); + ws2812_pwm.disable(pwm_channel); // wait another half second, so that we can see color change Timer::after_millis(500).await;