Tx and Rx setup

examples/rp/.idea/.gitignore

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+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

examples/rp/.idea/modules.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/rp.iml" filepath="$PROJECT_DIR$/.idea/rp.iml" />
+    </modules>
+  </component>
+</project>

examples/rp/.idea/rp.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+      <excludeFolder url="file://$MODULE_DIR$/target" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

examples/rp/.idea/vcs.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/../.." vcs="Git" />
+  </component>
+</project>

examples/rp/src/bin/pio_uart.rs

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+//! This example shows how to use USB (Universal Serial Bus) in the RP2040 chip.
+//!
+//! This creates a USB serial port that echos.
+
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{info, panic};
+use embassy_executor::Spawner;
+use embassy_futures::join::join;
+use embassy_rp::bind_interrupts;
+use embassy_rp::peripherals::{PIO0, USB};
+use embassy_rp::usb::{Driver, Instance, InterruptHandler};
+use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
+use embassy_usb::driver::EndpointError;
+use embassy_usb::{Builder, Config};
+use embassy_rp::pio::{InterruptHandler as PioInterruptHandler};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct UsbIrqs {
+    USBCTRL_IRQ => InterruptHandler<USB>;
+});
+
+bind_interrupts!(struct PioIrqs {
+    PIO0_IRQ_0 => PioInterruptHandler<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, UsbIrqs);
+
+    // 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;
+
+    // Required for windows compatibility.
+    // https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/kconfig/CONFIG_CDC_ACM_IAD.html#help
+    config.device_class = 0xEF;
+    config.device_sub_class = 0x02;
+    config.device_protocol = 0x01;
+    config.composite_with_iads = true;
+
+    // Create embassy-usb DeviceBuilder using the driver and config.
+    // It needs some buffers for building the descriptors.
+    let mut device_descriptor = [0; 256];
+    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 device_descriptor,
+        &mut config_descriptor,
+        &mut bos_descriptor,
+        &mut control_buf,
+    );
+
+    // Create classes on the builder.
+    let mut 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();
+
+    // Do stuff with the class!
+    let echo_fut = async {
+        loop {
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
+        }
+    };
+
+    // Run everything concurrently.
+    // If we had made everything `'static` above instead, we could do this using separate tasks instead.
+    join(usb_fut, echo_fut).await;
+}
+
+struct Disconnected {}
+
+impl From<EndpointError> for Disconnected {
+    fn from(val: EndpointError) -> Self {
+        match val {
+            EndpointError::BufferOverflow => panic!("Buffer overflow"),
+            EndpointError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}
+
+mod uart {
+    use embassy_rp::peripherals::PIO0;
+    use embassy_rp::pio::{Common, Pio, PioPin, StateMachine};
+    use embassy_rp::Peripheral;
+
+    use crate::PioIrqs;
+
+    pub struct PioUart<'a> {
+        baud: u64,
+        pio: Common<'a, PIO0>,
+        sm0: StateMachine<'a, PIO0, 0>,
+        sm1: StateMachine<'a, PIO0, 1>,
+    }
+
+    impl<'a> PioUart<'a> {
+        pub async fn new(
+            baud: u64,
+            pio: impl Peripheral<P = PIO0> + 'a,
+            tx_pin: impl PioPin,
+            rx_pin: impl PioPin,
+        ) -> PioUart<'a> {
+            let Pio {
+                mut common,
+                mut sm0,
+                mut sm1,
+                ..
+            } = Pio::new(pio, PioIrqs);
+
+            crate::uart_tx::setup_uart_tx_on_sm0(&mut common, &mut sm0, tx_pin, baud);
+            crate::uart_rx::setup_uart_rx_on_sm1(&mut common, &mut sm1, rx_pin, baud);
+
+            PioUart {
+                baud,
+                pio: common,
+                sm0,
+                sm1,
+            }
+        }
+    }
+}
+
+mod uart_tx {
+    use embassy_rp::gpio::Level;
+    use embassy_rp::peripherals::PIO0;
+    use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
+    use embassy_rp::relocate::RelocatedProgram;
+    use fixed::traits::ToFixed;
+    use fixed_macro::types::U56F8;
+
+    pub fn setup_uart_tx_on_sm0<'a>(
+        common: &mut Common<'a, PIO0>,
+        sm_tx: &mut StateMachine<'a, PIO0, 0>,
+        tx_pin: impl PioPin,
+        baud: u64,
+    ) {
+        let prg = pio_proc::pio_asm!(
+            r#"
+                ;.program uart_tx
+                .side_set 1 opt
+
+                ; An 8n1 UART transmit program.
+                ; OUT pin 0 and side-set pin 0 are both mapped to UART TX pin.
+
+                    pull       side 1 [7]  ; Assert stop bit, or stall with line in idle state
+                    set x, 7   side 0 [7]  ; Preload bit counter, assert start bit for 8 clocks
+                bitloop:                   ; This loop will run 8 times (8n1 UART)
+                    out pins, 1            ; Shift 1 bit from OSR to the first OUT pin
+                    jmp x-- bitloop   [6]  ; Each loop iteration is 8 cycles.
+            "#
+        );
+        let tx_pin = common.make_pio_pin(tx_pin);
+        sm_tx.set_pins(Level::High, &[&tx_pin]);
+        sm_tx.set_pin_dirs(Direction::Out, &[&tx_pin]);
+
+        let relocated = RelocatedProgram::new(&prg.program);
+        let mut cfg = Config::default();
+
+        cfg.use_program(&common.load_program(&relocated), &[&tx_pin]);
+        cfg.clock_divider = (U56F8!(125_000_000) / (8 * baud)).to_fixed();
+        cfg.shift_out.auto_fill = false;
+        cfg.shift_out.direction = ShiftDirection::Right;
+        cfg.fifo_join = FifoJoin::TxOnly;
+        cfg.set_out_pins(&[&tx_pin]);
+        cfg.set_set_pins(&[&tx_pin]);
+        sm_tx.set_config(&cfg);
+        sm_tx.set_enable(true)
+    }
+}
+
+mod uart_rx {
+    use embassy_rp::gpio::Level;
+    use embassy_rp::peripherals::PIO0;
+    use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
+    use embassy_rp::relocate::RelocatedProgram;
+    use fixed::traits::ToFixed;
+    use fixed_macro::types::U56F8;
+
+    pub fn setup_uart_rx_on_sm1<'a>(
+        common: &mut Common<'a, PIO0>,
+        sm_rx: &mut StateMachine<'a, PIO0, 1>,
+        rx_pin: impl PioPin,
+        baud: u64,
+    ) {
+        let prg = pio_proc::pio_asm!(
+            r#"
+                ;.program uart_rx
+
+                ; Slightly more fleshed-out 8n1 UART receiver which handles framing errors and
+                ; break conditions more gracefully.
+                ; IN pin 0 and JMP pin are both mapped to the GPIO used as UART RX.
+
+                start:
+                    wait 0 pin 0        ; Stall until start bit is asserted
+                    set x, 7    [10]    ; Preload bit counter, then delay until halfway through
+                bitloop:                ; the first data bit (12 cycles incl wait, set).
+                    in pins, 1          ; Shift data bit into ISR
+                    jmp x-- bitloop [6] ; Loop 8 times, each loop iteration is 8 cycles
+                    jmp pin good_stop   ; Check stop bit (should be high)
+
+                    irq 4 rel           ; Either a framing error or a break. Set a sticky flag,
+                    wait 1 pin 0        ; and wait for line to return to idle state.
+                    jmp start           ; Don't push data if we didn't see good framing.
+
+                good_stop:              ; No delay before returning to start; a little slack is
+                    push                ; important in case the TX clock is slightly too fast.
+            "#
+        );
+
+        let rx_pin = common.make_pio_pin(rx_pin);
+        sm_rx.set_pins(Level::High, &[&rx_pin]);
+        sm_rx.set_pin_dirs(Direction::In, &[&rx_pin]);
+
+        let relocated = RelocatedProgram::new(&prg.program);
+        let mut cfg = Config::default();
+
+        cfg.use_program(&common.load_program(&relocated), &[&rx_pin]);
+        cfg.clock_divider = (U56F8!(125_000_000) / (8 * baud)).to_fixed();
+        cfg.shift_out.auto_fill = false;
+        cfg.shift_out.direction = ShiftDirection::Right;
+        cfg.fifo_join = FifoJoin::RxOnly;
+        cfg.set_in_pins(&[&rx_pin]);
+        cfg.set_jmp_pin(&rx_pin);
+        // cfg.set_set_pins(&[&rx_pin]);
+        sm_rx.set_config(&cfg);
+        sm_rx.set_enable(true)
+    }
+}