NaxdyOrg/embassy
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

fix timing, turn TIM UDE on only necessary, clean DMA FEIF after each Transfer

Browse source
This commit is contained in:
eZio Pan 2023-12-22 01:24:31 +08:00
parent d7e517e2d3
commit 53fc344e4d
1 changed files with 12 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
examples/stm32f4/src/bin/ws2812_pwm_dma.rs
View file

@ -64,9 +64,6 @@ async fn main(_spawner: Spawner) {
CountingMode::EdgeAlignedUp,
);
// PAC level hacking, enable timer-update-event trigger DMA
pac::TIM3.dier().modify(|v| v.set_ude(true));
// construct ws2812 non-return-to-zero (NRZ) code bit by bit
// ws2812 only need 24 bits for each LED, but we add one bit more to keep PWM output low
@ -104,13 +101,16 @@ async fn main(_spawner: Spawner) {
dma_transfer_option.mburst = Burst::Incr8;
// flip color at 2 Hz
let mut ticker = Ticker::every(Duration::from_micros(500));
let mut ticker = Ticker::every(Duration::from_millis(500));
loop {
for &color in color_list {
// start PWM output
ws2812_pwm.enable(pwm_channel);
// PAC level hacking, enable timer-update-event trigger DMA
pac::TIM3.dier().modify(|v| v.set_ude(true));
unsafe {
Transfer::new_write(
// with &mut, we can easily reuse same DMA channel multiple times
@ -121,6 +121,14 @@ async fn main(_spawner: Spawner) {
dma_transfer_option,
)
.await;
// Turn off timer-update-event trigger DMA as soon as possible.
// Then clean the FIFO Error Flag if set.
pac::TIM3.dier().modify(|v| v.set_ude(false));
if pac::DMA1.isr(0).read().feif(2) {
pac::DMA1.ifcr(0).write(|v| v.set_feif(2, true));
}
// ws2812 need at least 50 us low level input to confirm the input data and change it's state
Timer::after_micros(50).await;
}