working with the dma library

.gitignore

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

dma_gpio2/Cargo.lock

@@ -295,7 +295,6 @@ dependencies = [
 [[package]]
 name = "embassy-embedded-hal"
 version = "0.5.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "defmt 1.0.1",
  "embassy-futures",
@@ -313,7 +312,6 @@ dependencies = [
 [[package]]
 name = "embassy-executor"
 version = "0.9.1"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "cordyceps",
  "cortex-m",
@@ -326,7 +324,6 @@ dependencies = [
 [[package]]
 name = "embassy-executor-macros"
 version = "0.7.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "darling",
  "proc-macro2",
@@ -337,17 +334,14 @@ dependencies = [
 [[package]]
 name = "embassy-executor-timer-queue"
 version = "0.1.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 
 [[package]]
 name = "embassy-futures"
 version = "0.1.2"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 
 [[package]]
 name = "embassy-hal-internal"
 version = "0.3.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "cortex-m",
  "critical-section",
@@ -358,7 +352,6 @@ dependencies = [
 [[package]]
 name = "embassy-net-driver"
 version = "0.2.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "defmt 1.0.1",
 ]
@@ -366,7 +359,6 @@ dependencies = [
 [[package]]
 name = "embassy-net-driver-channel"
 version = "0.3.2"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "embassy-futures",
  "embassy-net-driver",
@@ -376,7 +368,6 @@ dependencies = [
 [[package]]
 name = "embassy-stm32"
 version = "0.4.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "aligned",
  "bit_field",
@@ -425,7 +416,6 @@ dependencies = [
 [[package]]
 name = "embassy-sync"
 version = "0.7.2"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "cfg-if",
  "critical-section",
@@ -439,7 +429,6 @@ dependencies = [
 [[package]]
 name = "embassy-time"
 version = "0.5.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "cfg-if",
  "critical-section",
@@ -455,7 +444,6 @@ dependencies = [
 [[package]]
 name = "embassy-time-driver"
 version = "0.2.1"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "document-features",
 ]
@@ -463,7 +451,6 @@ dependencies = [
 [[package]]
 name = "embassy-time-queue-utils"
 version = "0.3.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "embassy-executor-timer-queue",
  "heapless 0.8.0",
@@ -472,7 +459,6 @@ dependencies = [
 [[package]]
 name = "embassy-usb"
 version = "0.5.1"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "embassy-futures",
  "embassy-net-driver-channel",
@@ -487,7 +473,6 @@ dependencies = [
 [[package]]
 name = "embassy-usb-driver"
 version = "0.2.0"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "defmt 1.0.1",
  "embedded-io-async",
@@ -496,7 +481,6 @@ dependencies = [
 [[package]]
 name = "embassy-usb-synopsys-otg"
 version = "0.3.1"
-source = "git+https://github.com/embassy-rs/embassy.git?branch=main#9b1add3d83e98c6c9ae9230bf35cd89bba530a20"
 dependencies = [
  "critical-section",
  "defmt 1.0.1",

dma_gpio2/Cargo.toml

@@ -10,13 +10,13 @@ cortex-m = { version = "0.7.7", features = ["inline-asm", "critical-section-sing
 cortex-m-rt = "0.7.5"
 panic-halt = "1.0.0"
 
-embassy-executor = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["arch-cortex-m", "executor-thread"] }
-embassy-futures = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
-embassy-sync    = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
-embassy-time    = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["tick-hz-32_768"] }
-embassy-hal-internal = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
-embassy-usb = { git = "https://github.com/embassy-rs/embassy.git", branch = "main" }
-embassy-stm32 = { git = "https://github.com/embassy-rs/embassy.git", branch = "main", features = ["unstable-pac", "stm32u575zi", "time-driver-tim2", "memory-x", "defmt"] }
+embassy-executor = { path = "/home/filip/programs/embassy/embassy-executor", features = ["arch-cortex-m", "executor-thread"] }
+embassy-futures = { path = "/home/filip/programs/embassy/embassy-futures" }
+embassy-sync = { path = "/home/filip/programs/embassy/embassy-sync" }
+embassy-time = { path = "/home/filip/programs/embassy/embassy-time", features = ["tick-hz-32_768"] }
+embassy-hal-internal = { path = "/home/filip/programs/embassy/embassy-hal-internal" }
+embassy-usb = { path = "/home/filip/programs/embassy/embassy-usb" }
+embassy-stm32 = { path = "/home/filip/programs/embassy/embassy-stm32", features = ["unstable-pac", "stm32u575zi", "time-driver-tim2", "memory-x", "defmt"] }
 
 embedded-hal = "1.0.0"
 embedded-graphics = "0.8.1"

dma_gpio2/src/bin/main.rs

@@ -1,95 +1,165 @@
 // src/bin/main.rs
-
 #![no_std]
 #![no_main]
 
 use defmt::*;
 use embassy_executor::Spawner;
 use embassy_futures::yield_now;
+use embassy_stm32::dma::Request;
 use embassy_stm32::gpio::{Input, Output, Level, Pull, Speed};
-use embassy_stm32::dma::{TransferOptions, Transfer, Priority, Request};
+use embassy_time::{Duration, Timer};
+use embassy_stm32::dma::{TransferOptions, WritableRingBuffer};
 use dma_gpio::software_uart::{
     dma_timer::init_tim6_for_uart,
     gpio_dma_uart_tx::encode_uart_frames,
     debug::dump_tim6_regs,
 };
-use dma_gpio::config::{BAUD, TX_PIN_BIT, TX_OVERSAMPLE};
+use dma_gpio::config::{BAUD, TX_PIN_BIT, TX_OVERSAMPLE, TX_RING_BYTES};
 use static_cell::StaticCell;
 use {defmt_rtt as _, panic_probe as _};
 
-unsafe fn start_dma<'a>(
-    ch: embassy_hal_internal::Peri<'a, impl embassy_stm32::dma::Channel>,
-    request: Request,
-    odr_ptr: *mut u32,
-    buf: &'a [u32],
-    opts: TransferOptions,
-) -> Transfer<'a> {
-    // new_write itself is unsafe
-    unsafe { Transfer::new_write(ch, request, buf, odr_ptr, opts) }
-}
-
 pub const TIM6_UP_REQ: Request = 4;
-const DMA_BUF_WORDS: usize = 256;
 
-static BUF_A: StaticCell<[u32; DMA_BUF_WORDS]> = StaticCell::new();
-static BUF_B: StaticCell<[u32; DMA_BUF_WORDS]> = StaticCell::new();
+static TX_RING: StaticCell<[u32; TX_RING_BYTES]> = StaticCell::new();
 
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
-    let odr_ptr = embassy_stm32::pac::GPIOA.odr().as_ptr() as *mut u32;
+    info!("Hehe");
+
+    let _rx = Input::new(p.PA3, embassy_stm32::gpio::Pull::Up);
+    let _tx = Output::new(p.PA2, Level::High, Speed::VeryHigh);
 
     init_tim6_for_uart(p.TIM6, BAUD, TX_OVERSAMPLE);
     dump_tim6_regs();
 
-    let buf_a = BUF_A.init([0u32; DMA_BUF_WORDS]);
-    let buf_b = BUF_B.init([0u32; DMA_BUF_WORDS]);
-    // Pre-fill with idle high level (stop bit level)
-    let idle = 1u32 << TX_PIN_BIT;
-    for w in buf_a.iter_mut() {
-        *w = idle;
-    }
-    for w in buf_b.iter_mut() {
-        *w = idle;
+    let idle: u32 = 1u32 << TX_PIN_BIT;
+
+    // Ring initialized to idle (line high).
+    let tx_ring_mem: &mut [u32; TX_RING_BYTES] = TX_RING.init([0; TX_RING_BYTES]);
+
+    let odr_ptr = embassy_stm32::pac::GPIOA.odr().as_ptr() as *mut u32;
+
+    let mut tx_opts = TransferOptions::default();
+    tx_opts.half_transfer_ir = true;
+    tx_opts.complete_transfer_ir = true;
+
+    let mut tx_ring = unsafe {
+        WritableRingBuffer::new(
+            p.GPDMA1_CH0,
+            TIM6_UP_REQ,
+            odr_ptr,
+            tx_ring_mem,
+            tx_opts,
+        )
+    };
+
+    {
+        // Full idle buffer matching ring capacity.
+        let idle_buf = [idle; TX_RING_BYTES];
+
+        let written = tx_ring
+            .write_exact(&idle_buf)
+            .await
+            .expect("Failed to prefill TX ring with idle");
+
+        info!(
+            "TX ring prefilled with idle via write_exact: written={} cap={}",
+            written,
+            tx_ring.capacity()
+        );
     }
 
-    let mut opts = TransferOptions::default();
-    opts.priority = Priority::VeryHigh;
-    opts.complete_transfer_ir = true;
+    tx_ring.start();
+    info!(
+        "TX DMA ring started: cap_words={}",
+        tx_ring.capacity()
+    );
+    unsafe {
+        use embassy_stm32::pac::gpdma::Gpdma;
+        let dma = Gpdma::from_ptr(0x4002_0000 as _); // GPDMA1 base for STM32U5
+        let ch = dma.ch(0); // Channel 0
 
-    let mut ch0 = p.GPDMA1_CH0;
-    let mut using_a = true;
+        let cr = ch.cr().read();
+        let tr1 = ch.tr1().read();
+        let tr2 = ch.tr2().read();
+        let br1 = ch.br1().read();
+        let sar = ch.sar().read();
+        let dar = ch.dar().read();
+        let llr = ch.llr().read();
+        let lbar = ch.lbar().read();
+
+        info!(
+            "GPDMA1_CH0: EN={} HTIE={} TCIE={} SDW={:?} DDW={:?} SINC={} DINC={} BNDT={} SAR=0x{:08x} DAR=0x{:08x}",
+            cr.en(),
+            cr.htie(),
+            cr.tcie(),
+            tr1.sdw(),
+            tr1.ddw(),
+            tr1.sinc(),
+            tr1.dinc(),
+            br1.bndt(),
+            sar, // already u32
+            dar, // already u32
+        );
+        info!(
+            "GPDMA1_CH0: LBAR=0x{:08x} LLR=0x{:08x}",
+            lbar.lba(),
+            llr.0
+        );
+    }
+
+    let mut frame_buf = [0u32; 4096];
 
     loop {
-        let (dma_buf, cpu_buf) = if using_a {
-            (&*buf_a, &mut *buf_b)
-        } else {
-            (&*buf_b, &mut *buf_a)
-        };
+        info!("tick start");
+        Timer::after(Duration::from_millis(1021)).await;
+        //info!("tick end");
 
-        // Start from idle pattern
-        let idle = 1u32 << TX_PIN_BIT;
-        for w in cpu_buf.iter_mut() {
-            *w = idle;
+        let used = encode_uart_frames(
+            TX_PIN_BIT,
+            b"H\r\n",
+            &mut frame_buf,
+        )
+        .await;
+
+        if used == 0 {
+            info!("encode_uart_frames() produced 0 words, skipping write");
+            yield_now().await;
+            continue;
         }
 
-        let used = encode_uart_frames(TX_PIN_BIT, b"Hello marshmallow\r\n", cpu_buf).await;
+        // Debug: confirm encoded content.
+        let preview = core::cmp::min(used, 32);
+        info!(
+            "TX frame used={} words, head={=[?]}",
+            used,
+            &frame_buf[..preview]
+        );
 
-        let len = if used == 0 { 1 } else { used };
-        // At least one word so DMA is always valid.
-
-        let transfer = unsafe {
-            start_dma(
-                ch0.reborrow(),
-                TIM6_UP_REQ,
-                odr_ptr,
-                &dma_buf[..len],
-                opts,
-            )
-        };
-        transfer.await;
-        using_a = !using_a;
+        // Now it is safe to call write_exact.
+        match tx_ring.write_exact(&frame_buf[..used]).await {
+            Ok(written) => {
+                let len = tx_ring.len().unwrap_or(0);
+                info!(
+                    "write_exact ok: written={} ring_used={} ring_cap={}",
+                    written,
+                    len,
+                    tx_ring.capacity()
+                );
+            }
+            Err(e) => {
+                let len = tx_ring.len().unwrap_or(0);
+                warn!(
+                    "write_exact error: {:?}, ring_used={} ring_cap={}",
+                    e,
+                    len,
+                    tx_ring.capacity()
+                );
+            }
+        }
 
+        info!("tick end");
         yield_now().await;
     }
 }