exti13.rs

    let device = hal::stm32f30x::Peripherals::take().unwrap();
    let mut core = Peripherals::take().unwrap();

    // Configure PC13 as an input
    device.RCC.ahbenr.modify(|_, w| w.iopcen().set_bit());
    device.GPIOC.moder.modify(
        |_, w| w.moder13().input()
    );
    device.GPIOC.pupdr.modify(|_, w| unsafe {
        w.pupdr13().bits(0b01)  // Pull-up
    });
    // Enable the EXTI13 interrupt
    core.NVIC.enable(
        stm32f30x::Interrupt::EXTI15_10,
    );
    // Connect GPIOC13 to EXTI13
    device.SYSCFG.exticr4.modify(|_, w| unsafe {
        w.exti13().bits(0b010)
    });
    // Enable interrupt on rise
    device.EXTI.imr1.modify(|_, w| w.mr13().set_bit());
    device.EXTI.emr1.modify(|_, w| w.mr13().set_bit());
    device.EXTI.rtsr1.modify(|_, w| w.tr13().set_bit());