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This commit is contained in:
Michael van Niekerk
2023-07-28 11:37:38 +02:00
parent a60d92cfbb
commit e947aa0153
2 changed files with 258 additions and 88 deletions
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345
examples/rp/src/bin/pio_uart.rs
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@@ -1,23 +1,35 @@
//! This example shows how to use USB (Universal Serial Bus) in the RP2040 chip.
//! 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 creates a USB serial port that echos.
//! 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]
#![feature(type_alias_impl_trait)]
#![feature(async_fn_in_trait)]
use defmt::{info, panic};
use defmt::{info, panic, trace};
use embassy_executor::Spawner;
use embassy_futures::join::join;
use embassy_futures::join::{join, join3};
use embassy_rp::bind_interrupts;
use embassy_rp::peripherals::{PIO0, USB};
use embassy_rp::pio::InterruptHandler as PioInterruptHandler;
use embassy_rp::usb::{Driver, Instance, InterruptHandler};
use embassy_usb::class::cdc_acm::{CdcAcmClass, State};
use embassy_sync::blocking_mutex::raw::ThreadModeRawMutex;
use embassy_sync::channel::Channel;
use embassy_usb::class::cdc_acm::{CdcAcmClass, Receiver, Sender, State};
use embassy_usb::driver::EndpointError;
use embassy_usb::{Builder, Config};
use embassy_rp::pio::{InterruptHandler as PioInterruptHandler};
use embedded_io::asynch::{Read, Write};
use {defmt_rtt as _, panic_probe as _};
use crate::uart::PioUart;
use crate::uart_rx::PioUartRx;
use crate::uart_tx::PioUartTx;
bind_interrupts!(struct UsbIrqs {
USBCTRL_IRQ => InterruptHandler<USB>;
});
@@ -69,7 +81,7 @@ async fn main(_spawner: Spawner) {
);
// Create classes on the builder.
let mut class = CdcAcmClass::new(&mut builder, &mut state, 64);
let class = CdcAcmClass::new(&mut builder, &mut state, 64);
// Build the builder.
let mut usb = builder.build();
@@ -77,19 +89,50 @@ async fn main(_spawner: Spawner) {
// Run the USB device.
let usb_fut = usb.run();
// Do stuff with the class!
let echo_fut = async {
// PIO UART setup
let uart = PioUart::new(9600, p.PIO0, p.PIN_4, p.PIN_5).await;
let (mut uart_tx, mut uart_rx) = uart.split();
// Channels setup
static USB_CHANNEL_TX: Channel<ThreadModeRawMutex, u8, 20> = Channel::<ThreadModeRawMutex, u8, 20>::new();
let mut usb_channel_tx_send = USB_CHANNEL_TX.sender();
let mut usb_channel_tx_recv = USB_CHANNEL_TX.receiver();
static UART_CHANNEL_TX: Channel<ThreadModeRawMutex, u8, 20> = Channel::<ThreadModeRawMutex, u8, 20>::new();
let mut uart_channel_tx_send = UART_CHANNEL_TX.sender();
let mut uart_channel_tx_recv = UART_CHANNEL_TX.receiver();
let (mut usb_tx, mut usb_rx) = class.split();
// Read + write from USB
let usb_future = async {
loop {
class.wait_connection().await;
info!("Wait for USB connection");
usb_rx.wait_connection().await;
info!("Connected");
let _ = echo(&mut class).await;
let _ = join(
usb_read(&mut usb_rx, &mut uart_channel_tx_send),
usb_write(&mut usb_tx, &mut usb_channel_tx_recv),
)
.await;
info!("Disconnected");
}
};
// Read + write from UART
let uart_future = async {
loop {
let _ = join(
uart_read(&mut uart_rx, &mut usb_channel_tx_send),
uart_write(&mut uart_tx, &mut uart_channel_tx_recv),
)
.await;
}
};
// 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;
join3(usb_fut, usb_future, uart_future).await;
}
struct Disconnected {}
@@ -103,28 +146,79 @@ impl From<EndpointError> for Disconnected {
}
}
async fn echo<'d, T: Instance + 'd>(class: &mut CdcAcmClass<'d, Driver<'d, T>>) -> Result<(), Disconnected> {
/// Read from the USB and write it to the UART TX send channel
async fn usb_read<'d, T: Instance + 'd>(
usb_rx: &mut Receiver<'d, Driver<'d, T>>,
uart_tx_send: &mut embassy_sync::channel::Sender<'d, ThreadModeRawMutex, u8, 20>,
) -> Result<(), Disconnected> {
let mut buf = [0; 64];
loop {
let n = class.read_packet(&mut buf).await?;
let n = usb_rx.read_packet(&mut buf).await?;
let data = &buf[..n];
info!("data: {:x}", data);
class.write_packet(data).await?;
trace!("USB IN: {:x}", data);
for byte in data {
uart_tx_send.send(*byte).await;
}
}
}
/// Read from the USB TX receive channel and write it to the USB
async fn usb_write<'d, T: Instance + 'd>(
usb_tx: &mut Sender<'d, Driver<'d, T>>,
usb_tx_recv: &mut embassy_sync::channel::Receiver<'d, ThreadModeRawMutex, u8, 20>,
) -> Result<(), Disconnected> {
loop {
let n = usb_tx_recv.recv().await;
let data = [n];
trace!("USB OUT: {:x}", data);
usb_tx.write_packet(&data).await?;
}
}
/// Read from the UART and write it to the USB TX send channel
async fn uart_read<'a>(
uart_rx: &mut PioUartRx<'a>,
usb_tx_send: &mut embassy_sync::channel::Sender<'a, ThreadModeRawMutex, u8, 20>,
) -> Result<(), Disconnected> {
let mut buf = [0; 1];
loop {
let n = uart_rx.read(&mut buf).await.expect("UART read error");
if n == 0 {
continue;
}
trace!("UART IN: {:x}", buf);
usb_tx_send.send(buf[0]).await;
}
}
/// Read from the UART TX receive channel and write it to the UART
async fn uart_write<'a>(
uart_tx: &mut PioUartTx<'a>,
uart_rx_recv: &mut embassy_sync::channel::Receiver<'a, ThreadModeRawMutex, u8, 20>,
) -> Result<(), Disconnected> {
loop {
let n = uart_rx_recv.recv().await;
let data = [n];
trace!("UART OUT: {:x}", data);
let _ = uart_tx.write(&data).await;
}
}
mod uart {
use embassy_rp::peripherals::PIO0;
use embassy_rp::pio::{Common, Pio, PioPin, StateMachine};
use embassy_rp::Peripheral;
use core::fmt::Debug;
use embassy_rp::peripherals::PIO0;
use embassy_rp::pio::{Pio, PioPin};
use embassy_rp::Peripheral;
use embedded_io::ErrorKind;
use crate::uart_rx::PioUartRx;
use crate::uart_tx::PioUartTx;
use crate::PioIrqs;
pub struct PioUart<'a> {
baud: u64,
pio: Common<'a, PIO0>,
sm0: StateMachine<'a, PIO0, 0>,
sm1: StateMachine<'a, PIO0, 1>,
tx: PioUartTx<'a>,
rx: PioUartRx<'a>,
}
impl<'a> PioUart<'a> {
@@ -135,21 +229,25 @@ mod uart {
rx_pin: impl PioPin,
) -> PioUart<'a> {
let Pio {
mut common,
mut sm0,
mut sm1,
..
mut common, sm0, 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);
let (tx, origin) = PioUartTx::new(&mut common, sm0, tx_pin, baud, None);
let (rx, _) = PioUartRx::new(&mut common, sm1, rx_pin, baud, Some(origin));
PioUart {
baud,
pio: common,
sm0,
sm1,
}
PioUart { tx, rx }
}
pub fn split(self) -> (PioUartTx<'a>, PioUartRx<'a>) {
(self.tx, self.rx)
}
}
#[derive(defmt::Format, Debug)]
pub struct PioUartError {}
impl embedded_io::Error for PioUartError {
fn kind(&self) -> ErrorKind {
ErrorKind::Other
}
}
}
@@ -159,18 +257,27 @@ mod uart_tx {
use embassy_rp::peripherals::PIO0;
use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
use embassy_rp::relocate::RelocatedProgram;
use embedded_io::asynch::Write;
use embedded_io::Io;
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
use crate::uart::PioUartError;
pub struct PioUartTx<'a> {
sm_tx: StateMachine<'a, PIO0, 0>,
}
impl<'a> PioUartTx<'a> {
pub fn new(
common: &mut Common<'a, PIO0>,
mut sm_tx: StateMachine<'a, PIO0, 0>,
tx_pin: impl PioPin,
baud: u64,
origin: Option<u8>,
) -> (Self, u8) {
let mut prg = pio_proc::pio_asm!(
r#"
.side_set 1 opt
; An 8n1 UART transmit program.
@@ -182,23 +289,55 @@ mod uart_tx {
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]);
);
prg.program.origin = origin;
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();
let relocated = RelocatedProgram::new(&prg.program);
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)
let mut cfg = Config::default();
cfg.set_out_pins(&[&tx_pin]);
cfg.use_program(&common.load_program(&relocated), &[&tx_pin]);
cfg.shift_out.auto_fill = false;
cfg.shift_out.direction = ShiftDirection::Right;
cfg.fifo_join = FifoJoin::TxOnly;
cfg.clock_divider = (U56F8!(125_000_000) / (8 * baud)).to_fixed();
sm_tx.set_config(&cfg);
sm_tx.set_enable(true);
// The 4 state machines of the PIO each have their own program counter that starts taking
// instructions at an offset (origin) of the 32 instruction "space" the PIO device has.
// It is up to the programmer to sort out where to place these instructions.
// From the pio_asm! macro you get a ProgramWithDefines which has a field .program.origin
// which takes an Option<u8>.
//
// When you load more than one RelocatedProgram into the PIO,
// you load your first program at origin = 0.
// The RelocatedProgram has .code().count() which returns a usize,
// for which you can then use as your next program's origin.
let offset = relocated.code().count() as u8 + origin.unwrap_or_default();
(Self { sm_tx }, offset)
}
pub async fn write_u8(&mut self, data: u8) {
self.sm_tx.tx().wait_push(data as u32).await;
}
}
impl Io for PioUartTx<'_> {
type Error = PioUartError;
}
impl Write for PioUartTx<'_> {
async fn write(&mut self, buf: &[u8]) -> Result<usize, PioUartError> {
for byte in buf {
self.write_u8(*byte).await;
}
Ok(buf.len())
}
}
}
@@ -207,19 +346,27 @@ mod uart_rx {
use embassy_rp::peripherals::PIO0;
use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
use embassy_rp::relocate::RelocatedProgram;
use embedded_io::asynch::Read;
use embedded_io::Io;
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
use crate::uart::PioUartError;
pub struct PioUartRx<'a> {
sm_rx: StateMachine<'a, PIO0, 1>,
}
impl<'a> PioUartRx<'a> {
pub fn new(
common: &mut Common<'a, PIO0>,
mut sm_rx: StateMachine<'a, PIO0, 1>,
rx_pin: impl PioPin,
baud: u64,
origin: Option<u8>,
) -> (Self, u8) {
let mut prg = pio_proc::pio_asm!(
r#"
; 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.
@@ -227,36 +374,58 @@ mod 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).
rx_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)
jmp x-- rx_bitloop [6] ; Loop 8 times, each loop iteration is 8 cycles
jmp pin good_rx_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
good_rx_stop: ; No delay before returning to start; a little slack is
push ; important in case the TX clock is slightly too fast.
"#
);
);
prg.program.origin = origin;
let relocated = RelocatedProgram::new(&prg.program);
let mut cfg = Config::default();
cfg.use_program(&common.load_program(&relocated), &[]);
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 rx_pin = common.make_pio_pin(rx_pin);
sm_rx.set_pins(Level::High, &[&rx_pin]);
cfg.set_in_pins(&[&rx_pin]);
cfg.set_jmp_pin(&rx_pin);
sm_rx.set_pin_dirs(Direction::In, &[&rx_pin]);
let relocated = RelocatedProgram::new(&prg.program);
let mut cfg = Config::default();
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;
sm_rx.set_config(&cfg);
sm_rx.set_enable(true);
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)
let offset = relocated.code().count() as u8 + origin.unwrap_or_default();
(Self { sm_rx }, offset)
}
pub async fn read_u8(&mut self) -> u8 {
self.sm_rx.rx().wait_pull().await as u8
}
}
impl Io for PioUartRx<'_> {
type Error = PioUartError;
}
impl Read for PioUartRx<'_> {
async fn read(&mut self, buf: &mut [u8]) -> Result<usize, PioUartError> {
let mut i = 0;
while i < buf.len() {
buf[i] = self.read_u8().await;
i += 1;
}
Ok(i)
}
}
}