//! # RAM Vector Table example //! //! This application demonstrates how to create a new Interrupt Vector Table in RAM. //! To demonstrate the extra utility of this, we also replace an entry in the Vector Table //! with a new one. //! //! See the `Cargo.toml` file for Copyright and license details. #![no_std] #![no_main] // Ensure we halt the program on panic use panic_halt as _; // Alias for our HAL crate use rp2040_hal as hal; // A shorter alias for the Peripheral Access Crate use hal::pac; // Some traits we need use core::cell::RefCell; use critical_section::Mutex; use embedded_hal::digital::v2::ToggleableOutputPin; use fugit::MicrosDurationU32; use pac::interrupt; use rp2040_hal::clocks::Clock; use rp2040_hal::timer::Alarm; use rp2040_hal::vector_table::VectorTable; // Memory that will hold our vector table in RAM static mut RAM_VTABLE: VectorTable = VectorTable::new(); // Give our LED and Alarm a type alias to make it easier to refer to them type LedAndAlarm = ( hal::gpio::Pin, hal::timer::Alarm0, ); // Place our LED and Alarm type in a static variable, so we can access it from interrupts static mut LED_AND_ALARM: Mutex>> = Mutex::new(RefCell::new(None)); // Period that each of the alarms will be set for - 1 second and 300ms respectively const SLOW_BLINK_INTERVAL_US: MicrosDurationU32 = MicrosDurationU32::secs(1); const FAST_BLINK_INTERVAL_US: MicrosDurationU32 = MicrosDurationU32::millis(300); /// The linker will place this boot block at the start of our program image. We /// need this to help the ROM bootloader get our code up and running. /// Note: This boot block is not necessary when using a rp-hal based BSP /// as the BSPs already perform this step. #[link_section = ".boot2"] #[used] pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_GENERIC_03H; /// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust /// if your board has a different frequency const XTAL_FREQ_HZ: u32 = 12_000_000u32; /// Entry point to our bare-metal application. /// /// The `#[rp2040_hal::entry]` macro ensures the Cortex-M start-up code calls this function /// as soon as all global variables and the spinlock are initialised. /// /// The function configures the RP2040 peripherals, then toggles a GPIO pin in /// an infinite loop. If there is an LED connected to that pin, it will blink. #[rp2040_hal::entry] fn main() -> ! { // Grab our singleton objects let mut pac = pac::Peripherals::take().unwrap(); let core = pac::CorePeripherals::take().unwrap(); // Set up the watchdog driver - needed by the clock setup code let mut watchdog = hal::Watchdog::new(pac.WATCHDOG); // The single-cycle I/O block controls our GPIO pins let sio = hal::Sio::new(pac.SIO); // Need to make a reference to the Peripheral Base at this scope to avoid confusing the borrow checker let ppb = &mut pac.PPB; unsafe { // Copy the vector table that cortex_m_rt produced into the RAM vector table RAM_VTABLE.init(ppb); // Replace the function that is called on Alarm0 interrupts with a new one RAM_VTABLE.register_handler(pac::Interrupt::TIMER_IRQ_0 as usize, timer_irq0_replacement); } // Configure the clocks let clocks = hal::clocks::init_clocks_and_plls( XTAL_FREQ_HZ, pac.XOSC, pac.CLOCKS, pac.PLL_SYS, pac.PLL_USB, &mut pac.RESETS, &mut watchdog, ) .ok() .unwrap(); // Create simple delay let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().to_Hz()); // Set the pins to their default state let pins = hal::gpio::Pins::new( pac.IO_BANK0, pac.PADS_BANK0, sio.gpio_bank0, &mut pac.RESETS, ); // Configure GPIO25 as an output let led_pin = pins.gpio25.into_push_pull_output(); let mut timer = hal::Timer::new(pac.TIMER, &mut pac.RESETS); critical_section::with(|cs| { let mut alarm = timer.alarm_0().unwrap(); // Schedule an alarm in 1 second let _ = alarm.schedule(SLOW_BLINK_INTERVAL_US); // Enable generating an interrupt on alarm alarm.enable_interrupt(); // Move alarm into ALARM, so that it can be accessed from interrupts unsafe { LED_AND_ALARM.borrow(cs).replace(Some((led_pin, alarm))); } }); // Unmask the timer0 IRQ so that it will generate an interrupt unsafe { pac::NVIC::unmask(pac::Interrupt::TIMER_IRQ_0); } // After 5 seconds, switch to our modified vector rable delay.delay_ms(5000); unsafe { critical_section::with(|_| { RAM_VTABLE.activate(ppb); }); } loop { // Wait for an interrupt to fire before doing any more work cortex_m::asm::wfi(); } } // Regular interrupt handler for Alarm0. The `interrupt` macro will perform some transformations to ensure // that this interrupt entry ends up in the vector table. #[interrupt] fn TIMER_IRQ_0() { critical_section::with(|cs| { // Temporarily take our LED_AND_ALARM let ledalarm = unsafe { LED_AND_ALARM.borrow(cs).take() }; if let Some((mut led, mut alarm)) = ledalarm { // Clear the alarm interrupt or this interrupt service routine will keep firing alarm.clear_interrupt(); // Schedule a new alarm after SLOW_BLINK_INTERVAL_US have passed (1 second) let _ = alarm.schedule(SLOW_BLINK_INTERVAL_US); // Blink the LED so we know we hit this interrupt led.toggle().unwrap(); // Return LED_AND_ALARM into our static variable unsafe { LED_AND_ALARM .borrow(cs) .replace_with(|_| Some((led, alarm))); } } }); } // This is the function we will use to replace TIMER_IRQ_0 in our RAM Vector Table extern "C" fn timer_irq0_replacement() { critical_section::with(|cs| { let ledalarm = unsafe { LED_AND_ALARM.borrow(cs).take() }; if let Some((mut led, mut alarm)) = ledalarm { // Clear the alarm interrupt or this interrupt service routine will keep firing alarm.clear_interrupt(); // Schedule a new alarm after FAST_BLINK_INTERVAL_US have passed (300 milliseconds) let _ = alarm.schedule(FAST_BLINK_INTERVAL_US); led.toggle().unwrap(); // Return LED_AND_ALARM into our static variable unsafe { LED_AND_ALARM .borrow(cs) .replace_with(|_| Some((led, alarm))); } } }); } // End of file