From 28b468902ad17856897c7dd96d74c6dcd3587b8b Mon Sep 17 00:00:00 2001
From: Priec <filippriec@gmail.com>
Date: Fri, 31 Oct 2025 14:31:25 +0100
Subject: [PATCH] Rx is not using dma now

---
 dma_gpio/src/bin/main.rs     | 19 +++++++++++---
 dma_gpio/src/gpio_uart_rx.rs | 48 ++++++++++++++++++++++++++++++++++++
 dma_gpio/src/lib.rs          |  1 +
 3 files changed, 65 insertions(+), 3 deletions(-)
 create mode 100644 dma_gpio/src/gpio_uart_rx.rs

diff --git a/dma_gpio/src/bin/main.rs b/dma_gpio/src/bin/main.rs
index 575ad42..6ef40d3 100644
--- a/dma_gpio/src/bin/main.rs
+++ b/dma_gpio/src/bin/main.rs
@@ -8,6 +8,9 @@ use embassy_executor::Spawner;
 use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
 use embassy_time::{Duration, Timer};
 use dma_gpio::dma_timer::init_tim6_for_uart;
+use embassy_stm32::gpio::Input;
+use embassy_stm32::gpio::Pull;
+use dma_gpio::gpio_uart_rx::GpioUartRx;
 use {defmt_rtt as _, panic_probe as _};
 
 use embassy_stm32::{
@@ -20,7 +23,8 @@ use dma_gpio::gpio_dma_uart::{
     write_uart_frames_to_pipe, GpioDmaBsrrTx, Parity, StopBits, UartConfig,
 };
 
-static PIPE: Pipe<CriticalSectionRawMutex, 256> = Pipe::new();
+static PIPE_TX: Pipe<CriticalSectionRawMutex, 256> = Pipe::new();
+static PIPE_RX: Pipe<CriticalSectionRawMutex, 256> = Pipe::new();
 
 // Baud rate: one TIM6 update equals one UART bit-time
 const BAUD: u32 = 115_200;
@@ -76,11 +80,20 @@ fn dump_dma_ch0_regs() {
     );
 }
 
+#[embassy_executor::task]
+async fn rx_task(pin: Input<'static>) {
+    let mut rx = GpioUartRx::new(pin, BAUD, UART_CFG, &PIPE_RX);
+    rx.run().await;
+}
+
 #[embassy_executor::main]
 async fn main(spawner: Spawner) {
     let p = embassy_stm32::init(Default::default());
     info!("DMA Pipe -> GPIO UART-like TX");
 
+    let pa3_rx = Input::new(p.PA3, Pull::Up);
+    spawner.spawn(rx_task(pa3_rx)).unwrap();
+
     // PA2 is the TX "wire"
     let _pa2 = Output::new(p.PA2, Level::High, Speed::VeryHigh);
     // drop(_pa2);
@@ -93,7 +106,7 @@ async fn main(spawner: Spawner) {
     // Example: transmit a string as UART frames via the Pipe
     loop {
         write_uart_frames_to_pipe(
-            &PIPE,
+            &PIPE_TX,
             TX_PIN_BIT,
             b"Hello, DMA UART (configurable)!\r\n",
             &UART_CFG,
@@ -110,7 +123,7 @@ async fn dma_tx_task(ch: Peri<'static, GPDMA1_CH0>) {
     loop {
         // Read one 32-bit BSRR word (4 bytes) from the Pipe
         let mut b = [0u8; 4];
-        let n = PIPE.read(&mut b).await;
+        let n = PIPE_TX.read(&mut b).await;
         if n != 4 {
             continue;
         }
diff --git a/dma_gpio/src/gpio_uart_rx.rs b/dma_gpio/src/gpio_uart_rx.rs
new file mode 100644
index 0000000..a72da8e
--- /dev/null
+++ b/dma_gpio/src/gpio_uart_rx.rs
@@ -0,0 +1,48 @@
+// src/gpio_uart_rx.rs
+
+use embassy_stm32::gpio::{Input, Level, Pull};
+use embassy_sync::{blocking_mutex::raw::CriticalSectionRawMutex, pipe::Pipe};
+use embassy_time::{Timer, Duration};
+use crate::gpio_dma_uart::UartConfig;
+
+/// Simplified bit-banged UART RX using a timer for sampling.
+/// Sample pin every bit-time once start bit is detected.
+pub struct GpioUartRx<'d, const N: usize> {
+    pin: Input<'d>,
+    baud: u32,
+    cfg: UartConfig,
+    pipe: &'d Pipe<CriticalSectionRawMutex, N>,
+}
+
+impl<'d, const N: usize> GpioUartRx<'d, N> {
+    pub fn new(pin: Input<'d>, baud: u32, cfg: UartConfig, pipe: &'d Pipe<CriticalSectionRawMutex, N>) -> Self {
+        Self { pin, baud, cfg, pipe }
+    }
+
+    /// Async read loop: waits for start bit, samples bits, pushes received byte into pipe.
+    pub async fn run(&mut self) -> ! {
+        let bit_time = Duration::from_hz(self.baud.into());
+
+        loop {
+            // Wait for start bit edge
+            while self.pin.get_level() == Level::High {
+                Timer::after_micros(1).await;
+            }
+
+            // Skip only 1 bit-time since you *don’t* want 1.5 bit delay
+            Timer::after(bit_time).await;
+
+            let nbits = self.cfg.data_bits.clamp(5, 8);
+            let mut data = 0u8;
+            for i in 0..nbits {
+                if self.pin.get_level() == Level::High {
+                    data |= 1 << i;
+                }
+                Timer::after(bit_time).await;
+            }
+
+            // push into Pipe as soon as byte is complete
+            self.pipe.write(&[data]).await;
+        }
+    }
+}
diff --git a/dma_gpio/src/lib.rs b/dma_gpio/src/lib.rs
index 26fe4b2..92f6125 100644
--- a/dma_gpio/src/lib.rs
+++ b/dma_gpio/src/lib.rs
@@ -5,3 +5,4 @@ pub use gpio_dma_uart::*;
 
 pub mod dma_timer;
 pub use dma_timer::*;
+pub mod gpio_uart_rx;