music.rs

extern fn isr_rtc0();

#[allow(non_upper_case_globals)]
#[link_section=".isr_vector_nvic"]
#[no_mangle]
pub static NVICVectors: [Option<unsafe extern fn()>; ISR_COUNT+1] = [
  None,
  Some(isr_power_clock),
  ...
  Some(isr_rtc0),
  ...
];

...

use zinc::hal::cortex_m0::{irq,nvic};
nrf51822::rtc::RTC.set_prescaler(0);
nrf51822::sleep_us(100000);
nrf51822::rtc::RTC.enable_tick_iterrupt();
nvic::enable_irq(11);
nrf51822::rtc::RTC.start();

...,

#[no_mangle]
pub unsafe extern fn isr_rtc0() {
    nrf51822::rtc::RTC.clear_tick();
    music::tick()
}