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update pico_usb_serial_interrupt
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@ithinuel
ithinuel committed Aug 15, 2023
1 parent 5fd8238 commit fb5b54a
Showing 1 changed file with 118 additions and 91 deletions.
209 changes: 118 additions & 91 deletions boards/rp-pico/examples/pico_usb_serial_interrupt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,22 +12,31 @@
#![no_std]
#![no_main]

// A cell to be used with `critical_section::Mutex`
use core::cell::RefCell;

// Trait required to use `writeln!(…)`
use core::fmt::Write;

// A system wide mutex synchrinising IRQ & cores
use critical_section::Mutex;

// Import common embedded_hal traits
use embedded_hal::prelude::*;

// The macro for marking out exception function
use cortex_m_rt::exception;

// The macro for our start-up function
use rp_pico::entry;

// The macro for marking our interrupt functions
use rp_pico::hal::pac::interrupt;

// GPIO traits
use embedded_hal::digital::v2::OutputPin;

// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;

// Pull in any important traits
use rp_pico::hal::prelude::*;

// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use rp_pico::hal::pac;
Expand All @@ -42,14 +51,28 @@ use usb_device::{class_prelude::*, prelude::*};
// USB Communications Class Device support
use usbd_serial::SerialPort;

/// The USB Device Driver (shared with the interrupt).
static mut USB_DEVICE: Option<UsbDevice<hal::usb::UsbBus>> = None;
struct StaticUsb<'a> {
usb_device: UsbDevice<'a, hal::usb::UsbBus>,
usb_serial: SerialPort<'a, hal::usb::UsbBus>,
}

/// The USB Bus Driver (shared with the interrupt).
static mut USB_BUS: Option<UsbBusAllocator<hal::usb::UsbBus>> = None;
// shared with the interrupt
static STATIC_USB: Mutex<RefCell<Option<StaticUsb>>> = Mutex::new(RefCell::new(None));

/// The USB Serial Device Driver (shared with the interrupt).
static mut USB_SERIAL: Option<SerialPort<hal::usb::UsbBus>> = None;
/// Call the closure within a critical section passing the content of `STATIC_USB`.
///
/// This function `panic!`s if `STATIC_USB` does not contain `Some` value.
fn do_with_usb<T>(closure: impl FnOnce(&mut StaticUsb) -> T) -> T {
critical_section::with(|cs| {
// Create a mutable local binding for the RefMut type wrapping our Option<StaticUsb>.
let mut usb = STATIC_USB.borrow_ref_mut(cs);
// Borrow the content of that binding.
let usb = usb
.as_mut()
.expect("Usb must be setup before calling this function.");
closure(usb)
})
}

/// Entry point to our bare-metal application.
///
Expand All @@ -60,9 +83,12 @@ static mut USB_SERIAL: Option<SerialPort<hal::usb::UsbBus>> = None;
/// infinite loop.
#[entry]
fn main() -> ! {
// The USB Bus Driver (shared with the interrupt).
static mut USB_BUS: Option<UsbBusAllocator<hal::usb::UsbBus>> = None;

// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
let core = pac::CorePeripherals::take().unwrap();
let mut core = pac::CorePeripherals::take().unwrap();

// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
Expand All @@ -82,75 +108,82 @@ fn main() -> ! {
.ok()
.unwrap();

// The delay object lets us wait for specified amounts of time (in milliseconds)
let mut delay = hal::Timer::new(pac.TIMER, &mut pac.RESETS, &clocks);

// Set up the USB driver
let usb_bus = UsbBusAllocator::new(hal::usb::UsbBus::new(
*USB_BUS = Some(UsbBusAllocator::new(hal::usb::UsbBus::new(
pac.USBCTRL_REGS,
pac.USBCTRL_DPRAM,
clocks.usb_clock,
true,
&mut pac.RESETS,
));
unsafe {
// Note (safety): This is safe as interrupts haven't been started yet
USB_BUS = Some(usb_bus);
}
)));

// Grab a reference to the USB Bus allocator. We are promising to the
// compiler not to take mutable access to this global variable whilst this
// reference exists!
let bus_ref = unsafe { USB_BUS.as_ref().unwrap() };
let bus_ref = USB_BUS.as_mut().unwrap();

// Set up the USB Communications Class Device driver
let serial = SerialPort::new(bus_ref);
unsafe {
USB_SERIAL = Some(serial);
}

let usb_serial = SerialPort::new(bus_ref);
// Create a USB device with a fake VID and PID
let usb_dev = UsbDeviceBuilder::new(bus_ref, UsbVidPid(0x16c0, 0x27dd))
let usb_device = UsbDeviceBuilder::new(bus_ref, UsbVidPid(0x16c0, 0x27dd))
.manufacturer("Fake company")
.product("Serial port")
.serial_number("TEST")
.device_class(2) // from: https://www.usb.org/defined-class-codes
.build();
unsafe {
// Note (safety): This is safe as interrupts haven't been started yet
USB_DEVICE = Some(usb_dev);
}

// Setup the shared usb items in their global storage.
critical_section::with(|cs| {
STATIC_USB.replace(
cs,
Some(StaticUsb {
usb_device,
usb_serial,
}),
);
});

// How many system clock ticks are there in a 100th of a second (10ms)?
let ticks = pac::SYST::get_ticks_per_10ms();

// Setup SysTick for a 10ms periodic interrupt.
core.SYST.set_reload(ticks);
core.SYST.enable_counter();
core.SYST.enable_interrupt();

// Enable the USB interrupt
unsafe {
pac::NVIC::unmask(hal::pac::Interrupt::USBCTRL_IRQ);
};

// No more USB code after this point in main! We can do anything we want in
// here since USB is handled in the interrupt - let's blink an LED!

// The delay object lets us wait for specified amounts of time (in
// milliseconds)
let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().to_Hz());

// The single-cycle I/O block controls our GPIO pins
let sio = hal::Sio::new(pac.SIO);
// wait for the usb device to be configured (aka enumerated on a host).
while do_with_usb(|u| u.usb_device.state()) != UsbDeviceState::Configured {
delay.delay_ms(1);
}

// Set the pins up according to their function on this particular board
let pins = rp_pico::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
// Print a loop count every 2 seconds up to 10 times, then reset to usb boot.
for i in 0..10 {
delay.delay_ms(2_000);

// Set the LED to be an output
let mut led_pin = pins.led.into_push_pull_output();
let mut text = heapless::String::<20>::new();
writeln!(&mut text, "loop number: {}", i).unwrap();

// Blink the LED at 1 Hz
loop {
led_pin.set_high().unwrap();
delay.delay_ms(500);
led_pin.set_low().unwrap();
delay.delay_ms(500);
write_serial(text.as_bytes());
}
delay.delay_ms(2_000);
hal::rom_data::reset_to_usb_boot(0, 0);
unreachable!();
}

/// Writes to the serial port.
///
/// We do this with in a system wide critical-section to avoid a race hazard with the USB IRQ and
/// the other core (although this example does not use it).
fn write_serial(byte_array: &[u8]) {
let _ = do_with_usb(|u| u.usb_serial.write(byte_array));
}

/// This function is called whenever the USB Hardware generates an Interrupt
Expand All @@ -160,48 +193,42 @@ fn main() -> ! {
/// knowing nothing about USB.
#[allow(non_snake_case)]
#[interrupt]
unsafe fn USBCTRL_IRQ() {
use core::sync::atomic::{AtomicBool, Ordering};

/// Note whether we've already printed the "hello" message.
static SAID_HELLO: AtomicBool = AtomicBool::new(false);

fn USBCTRL_IRQ() {
// Grab the global objects. This is OK as we only access them under interrupt.
let usb_dev = USB_DEVICE.as_mut().unwrap();
let serial = USB_SERIAL.as_mut().unwrap();

// Say hello exactly once on start-up
if !SAID_HELLO.load(Ordering::Relaxed) {
SAID_HELLO.store(true, Ordering::Relaxed);
let _ = serial.write(b"Hello, World!\r\n");
}

// Poll the USB driver with all of our supported USB Classes
if usb_dev.poll(&mut [serial]) {
let mut buf = [0u8; 64];
match serial.read(&mut buf) {
Err(_e) => {
// Do nothing
}
Ok(0) => {
// Do nothing
}
Ok(count) => {
// Convert to upper case
buf.iter_mut().take(count).for_each(|b| {
b.make_ascii_uppercase();
});

// Send back to the host
let mut wr_ptr = &buf[..count];
while !wr_ptr.is_empty() {
let _ = serial.write(wr_ptr).map(|len| {
wr_ptr = &wr_ptr[len..];
do_with_usb(|usb| {
// Poll the USB driver with all of our supported USB Classes
if usb.usb_device.poll(&mut [&mut usb.usb_serial]) {
let mut buf = [0u8; 64];
match usb.usb_serial.read(&mut buf) {
Err(_e) => {
// Do nothing
}
Ok(0) => {
// Do nothing
}
Ok(count) => {
// Convert to upper case
buf.iter_mut().take(count).for_each(|b| {
b.make_ascii_uppercase();
});

// Send back to the host
let mut wr_ptr = &buf[..count];
while !wr_ptr.is_empty() {
let _ = usb.usb_serial.write(wr_ptr).map(|len| {
wr_ptr = &wr_ptr[len..];
});
}
}
}
}
}
});
}

#[allow(non_snake_case)]
#[exception]
fn SysTick() {
do_with_usb(|usb| usb.usb_device.poll(&mut [&mut usb.usb_serial]));
}

// End of file

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