not working, i have no clue why

.gitignore

@@ -1 +1,2 @@
 *.pdf
+dma_example/

dma_gpio2/src/bin/main.rs

@@ -17,33 +17,16 @@ use dma_gpio::software_uart::{
 };
 use dma_gpio::config::{BAUD, TX_PIN_BIT, RX_OVERSAMPLE, TX_OVERSAMPLE};
 use dma_gpio::config::{TX_RING_BYTES, RX_RING_BYTES, PIPE_RX_SIZE};
+use dma_gpio::software_uart::dump_dma_ch0_regs;
 use static_cell::StaticCell;
 use {defmt_rtt as _, panic_probe as _};
 
 // kapitola 17.4.11 - 2 casovace pre 2 DMA
-pub const TIM6_UP_REQ: Request = 4; // Table 137: tim6_upd_dma, strana 687 STM32U5xx datasheet
+// pub const TIM6_UP_REQ: Request = 4; // Table 137: tim6_upd_dma, strana 687 STM32U5xx datasheet
+pub const TIM6_UP_REQ: u8 = 4;
 
 static TX_RING: StaticCell<[u32; TX_RING_BYTES]> = StaticCell::new();
 
-use core::future::poll_fn;
-use core::task::Poll;
-
-async fn wait_for_space<'a, W: embassy_stm32::dma::word::Word>(
-    ring: &mut embassy_stm32::dma::WritableRingBuffer<'a, W>,
-    min_free: usize,
-) {
-    poll_fn(|cx| {
-        let used = ring.len().unwrap_or(0);
-        let cap = ring.capacity();
-        if cap - used > min_free {
-            Poll::Ready(())
-        } else {
-            ring.set_waker(cx.waker());
-            Poll::Pending
-        }
-    }).await
-}
-
 #[embassy_executor::main]
 async fn main(spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
@@ -58,6 +41,11 @@ async fn main(spawner: Spawner) {
     // Safe one-time init from StaticCell
     let tx_ring_mem: &mut [u32; TX_RING_BYTES] = TX_RING.init([0; TX_RING_BYTES]);
 
+    let pin_mask = 1u32 << TX_PIN_BIT;
+    for (i, w) in tx_ring_mem.iter_mut().enumerate() {
+        *w = if (i & 1) == 0 { 0 } else { pin_mask };
+    }
+
     // Create and start the TX DMA ring in main.
     // let bsrr_ptr = embassy_stm32::pac::GPIOA.bsrr().as_ptr() as *mut u32;
     let odr_ptr = embassy_stm32::pac::GPIOA.odr().as_ptr() as *mut u32;
@@ -78,6 +66,7 @@ async fn main(spawner: Spawner) {
     // Start DMA
     tx_ring.start();
     info!("TX DMA ring started");
+    dump_dma_ch0_regs();
 
     let mut frame_buf = [0u32; 4096];
 
@@ -86,16 +75,25 @@ async fn main(spawner: Spawner) {
         Timer::after(Duration::from_millis(400)).await;
         info!("tick end");
 
-        let used = encode_uart_frames(TX_PIN_BIT, b"Hello marshmallow\r\n", &mut frame_buf).await;
-
-        // Wait for DMA to free space, async style
-        wait_for_space(&mut tx_ring, used / 2).await;
+        // PHASE 1A (safest to validate hardware first): do nothing here; the DMA already
+        // streams the primed toggle pattern in tx_ring_mem. You should see PA2 toggling.
+        // Uncomment PHASE 1B below once you confirm toggling on a scope/LED.
 
+        // PHASE 1B: actively queue new data (only after confirming DMA advances).
+        let used = 256.min(frame_buf.len());
+        for i in 0..used { frame_buf[i] = if (i & 1) == 0 { 0 } else { pin_mask }; }
+        info!("a");
+        let free = tx_ring.capacity() - tx_ring.len().unwrap_or(0);
+        if free >= used {
             if let Err(e) = tx_ring.write_exact(&frame_buf[..used]).await {
                 warn!("DMA ring write error: {:?}", e);
             } else {
-            info!("Frame queued to DMA ring");
+                info!("Frame queued to DMA ring (free={})", free);
             }
+        } else {
+            warn!("Skipping write (free={}, need={})", free, used);
+        }
+        info!("b");
 
         yield_now().await;
     }

dma_gpio2/src/config.rs

@@ -4,9 +4,9 @@ use crate::software_uart::uart_emulation::{Parity, StopBits, UartConfig};
 pub const BAUD: u32 = 9_600;
 pub const TX_PIN_BIT: u8 = 2; // PA2
 pub const TX_OVERSAMPLE: u16 = 1;
-pub const RX_OVERSAMPLE: u16 = 16;
+pub const RX_OVERSAMPLE: u16 = 1;
 pub const RX_RING_BYTES: usize = 4096;
-pub const TX_RING_BYTES: usize = 4096;
+pub const TX_RING_BYTES: usize = 256;
 pub const PIPE_RX_SIZE: usize = 256;
 
 pub const UART_CFG: UartConfig = UartConfig {