1 files changed, 190 insertions, 0 deletions

diff --git a/examples/rp235x/src/bin/pio_uart.rs b/examples/rp235x/src/bin/pio_uart.rs
new file mode 100644
index 000000000..9712984f9
--- /dev/null
+++ b/examples/rp235x/src/bin/pio_uart.rs
@@ -0,0 +1,190 @@
+//! This example shows how to use the PIO module in the RP2040 chip to implement a duplex UART.
+//! The PIO module is a very powerful peripheral that can be used to implement many different
+//! protocols. It is a very flexible state machine that can be programmed to do almost anything.
+//!
+//! This example opens up a USB device that implements a CDC ACM serial port. It then uses the
+//! PIO module to implement a UART that is connected to the USB serial port. This allows you to
+//! communicate with a device connected to the RP2040 over USB serial.
+
+#![no_std]
+#![no_main]
+#![allow(async_fn_in_trait)]
+
+use defmt::{info, panic, trace};
+use embassy_executor::Spawner;
+use embassy_futures::join::{join, join3};
+use embassy_rp::peripherals::{PIO0, USB};
+use embassy_rp::pio_programs::uart::{PioUartRx, PioUartRxProgram, PioUartTx, PioUartTxProgram};
+use embassy_rp::usb::{Driver, Instance, InterruptHandler};
+use embassy_rp::{bind_interrupts, pio};
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_sync::pipe::Pipe;
+use embassy_usb::class::cdc_acm::{CdcAcmClass, Receiver, Sender, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::{Builder, Config};
+use embedded_io_async::{Read, Write};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    USBCTRL_IRQ => InterruptHandler<USB>;
+    PIO0_IRQ_0 => pio::InterruptHandler<PIO0>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Hello there!");
+
+    let p = embassy_rp::init(Default::default());
+
+    // Create the driver, from the HAL.
+    let driver = Driver::new(p.USB, Irqs);
+
+    // Create embassy-usb Config
+    let mut config = Config::new(0xc0de, 0xcafe);
+    config.manufacturer = Some("Embassy");
+    config.product = Some("PIO UART example");
+    config.serial_number = Some("12345678");
+    config.max_power = 100;
+    config.max_packet_size_0 = 64;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut config_descriptor = [0; 256];
+    let mut bos_descriptor = [0; 256];
+    let mut control_buf = [0; 64];
+
+    let mut state = State::new();
+
+    let mut builder = Builder::new(
+        driver,
+        config,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut [], // no msos descriptors
+        &mut control_buf,
+    );
+
+    // Create classes on the builder.
+    let class = CdcAcmClass::new(&mut builder, &mut state, 64);
+
+    // Build the builder.
+    let mut usb = builder.build();
+
+    // Run the USB device.
+    let usb_fut = usb.run();
+
+    // PIO UART setup
+    let pio::Pio {
+        mut common, sm0, sm1, ..
+    } = pio::Pio::new(p.PIO0, Irqs);
+
+    let tx_program = PioUartTxProgram::new(&mut common);
+    let mut uart_tx = PioUartTx::new(9600, &mut common, sm0, p.PIN_4, &tx_program);
+
+    let rx_program = PioUartRxProgram::new(&mut common);
+    let mut uart_rx = PioUartRx::new(9600, &mut common, sm1, p.PIN_5, &rx_program);
+
+    // Pipe setup
+    let mut usb_pipe: Pipe<NoopRawMutex, 20> = Pipe::new();
+    let (mut usb_pipe_reader, mut usb_pipe_writer) = usb_pipe.split();
+
+    let mut uart_pipe: Pipe<NoopRawMutex, 20> = Pipe::new();
+    let (mut uart_pipe_reader, mut uart_pipe_writer) = uart_pipe.split();
+
+    let (mut usb_tx, mut usb_rx) = class.split();
+
+    // Read + write from USB
+    let usb_future = async {
+        loop {
+            info!("Wait for USB connection");
+            usb_rx.wait_connection().await;
+            info!("Connected");
+            let _ = join(
+                usb_read(&mut usb_rx, &mut uart_pipe_writer),
+                usb_write(&mut usb_tx, &mut usb_pipe_reader),
+            )
+            .await;
+            info!("Disconnected");
+        }
+    };
+
+    // Read + write from UART
+    let uart_future = join(
+        uart_read(&mut uart_rx, &mut usb_pipe_writer),
+        uart_write(&mut uart_tx, &mut uart_pipe_reader),
+    );
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join3(usb_fut, usb_future, uart_future).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+/// Read from the USB and write it to the UART TX pipe
+async fn usb_read<'d, T: Instance + 'd>(
+    usb_rx: &mut Receiver<'d, Driver<'d, T>>,
+    uart_pipe_writer: &mut embassy_sync::pipe::Writer<'_, NoopRawMutex, 20>,
+) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = usb_rx.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        trace!("USB IN: {:x}", data);
+        (*uart_pipe_writer).write(data).await;
+    }
+}
+
+/// Read from the USB TX pipe and write it to the USB
+async fn usb_write<'d, T: Instance + 'd>(
+    usb_tx: &mut Sender<'d, Driver<'d, T>>,
+    usb_pipe_reader: &mut embassy_sync::pipe::Reader<'_, NoopRawMutex, 20>,
+) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = (*usb_pipe_reader).read(&mut buf).await;
+        let data = &buf[..n];
+        trace!("USB OUT: {:x}", data);
+        usb_tx.write_packet(&data).await?;
+    }
+}
+
+/// Read from the UART and write it to the USB TX pipe
+async fn uart_read<PIO: pio::Instance, const SM: usize>(
+    uart_rx: &mut PioUartRx<'_, PIO, SM>,
+    usb_pipe_writer: &mut embassy_sync::pipe::Writer<'_, NoopRawMutex, 20>,
+) -> ! {
+    let mut buf = [0; 64];
+    loop {
+        let n = uart_rx.read(&mut buf).await.expect("UART read error");
+        if n == 0 {
+            continue;
+        }
+        let data = &buf[..n];
+        trace!("UART IN: {:x}", buf);
+        (*usb_pipe_writer).write(data).await;
+    }
+}
+
+/// Read from the UART TX pipe and write it to the UART
+async fn uart_write<PIO: pio::Instance, const SM: usize>(
+    uart_tx: &mut PioUartTx<'_, PIO, SM>,
+    uart_pipe_reader: &mut embassy_sync::pipe::Reader<'_, NoopRawMutex, 20>,
+) -> ! {
+    let mut buf = [0; 64];
+    loop {
+        let n = (*uart_pipe_reader).read(&mut buf).await;
+        let data = &buf[..n];
+        trace!("UART OUT: {:x}", data);
+        let _ = uart_tx.write(&data).await;
+    }
+}