display: Add update timer.

display/firmware/Cargo.lock

 [[package]]
 name = "mkl25z4-hal"
 version = "0.1.0"
-source = "git+https://github.com/mgottschlag/mkl25z4-hal#80bcfffaef6da16a8257cc8478dba026f618c5f0"
+source = "git+https://github.com/mgottschlag/mkl25z4-hal#743740c348d24bd9ba22724b1cce62ff3c93078b"
 dependencies = [
  "cortex-m 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "embedded-hal 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",

display/firmware/src/main.rs

     include!(concat!(env!("OUT_DIR"), "/assets.rs"));
 }
 
+use cortex_m::peripheral::NVIC;
+use embedded_hal::timer::CountDown;
 use mkl25z4_hal::clocks::ClockConfiguration;
+use mkl25z4_hal::mkl25z4::{Interrupt, LPTMR0};
 use mkl25z4_hal::time::{CopyableMonoTimer, NonCopyableMonoTimer, U32Ext};
+use mkl25z4_hal::timer::Timer;
+use mkl25z4_hal::timer::TimerInterrupt;
 use panic_semihosting as _;
 
 use display::{Display, DisplayState};
         bme_pins: Option<BME280Pins>,
         radio: Option<Radio>,
         time: CopyableMonoTimer,
+        update_timer: Timer<LPTMR0>,
     }
 
     #[init(spawn = [fetch_update])]
 
         let radio = Radio::init(pins.nrf, time);
 
+        let update_timer = Timer::lptmr0(ctx.device.LPTMR0, 10.s(), clocks, &mut sim);
+        update_timer.enable_interrupt();
+        unsafe { NVIC::unmask(Interrupt::LPTMR0) };
+
         // Fetch the first update.
         ctx.spawn.fetch_update().ok();
 
             bme_pins: Some(pins.bme),
             radio: Some(radio),
             time,
+            update_timer,
         }
     }
 
-    #[task(binds = LPTMR0, priority = 3, spawn = [fetch_update])]
+    #[task(binds = LPTMR0, priority = 3, spawn = [fetch_update], resources = [update_timer])]
     fn lptmr0_interrupt(ctx: lptmr0_interrupt::Context) {
         // Restart the timer.
-        // TODO
+        ctx.resources.update_timer.start(10.s());
+        ctx.resources.update_timer.enable_interrupt();
 
         // Trigger an update of the displayed values.
         ctx.spawn.fetch_update().ok();