LED access function

src/main.rs

@@ -11,6 +11,20 @@ use cortex_m::ctxt::Local;
 use cortex_m::exception::Handlers as ExceptionHandlers;
 use tm4c129x::interrupt::Handlers as InterruptHandlers;
 
+const LED1: u8 = 0x10;
+const LED2: u8 = 0x40;
+
+fn set_led(nr: u8, state: bool) {
+    cortex_m::interrupt::free(|cs| {
+        let gpio_k = tm4c129x::GPIO_PORTK.borrow(cs);
+        if state {
+            gpio_k.data.modify(|r, w| w.data().bits(r.data().bits() | nr))
+        } else {
+            gpio_k.data.modify(|r, w| w.data().bits(r.data().bits() & !nr))
+        }
+    });
+}
+
 fn main() {
     hprintln!("Hello, world!");
 
@@ -19,17 +33,18 @@ fn main() {
         let sysctl  = tm4c129x::SYSCTL.borrow(cs);
         let gpio_k  = tm4c129x::GPIO_PORTK.borrow(cs);
 
+        // Bring up GPIO port K
+        sysctl.rcgcgpio.modify(|_, w| w.r9().bit(true));
+        while !sysctl.prgpio.read().r9().bit() {}
+
+        // Set up LEDs
+        gpio_k.dir.write(|w| w.dir().bits(LED1|LED2));
+        gpio_k.den.write(|w| w.den().bits(LED1|LED2));
+
         // Set up system timer
         systick.set_reload(systick.get_ticks_per_10ms());
         systick.enable_counter();
         systick.enable_interrupt();
-
-        // Set up LED
-        sysctl.rcgcgpio.modify(|_, w| w.r9().bit(true));
-        while !sysctl.prgpio.read().r9().bit() {}
-
-        gpio_k.dir.write(|w| w.dir().bits(0x10));
-        gpio_k.den.write(|w| w.den().bits(0x10));
     });
 }
 
@@ -40,14 +55,14 @@ extern fn sys_tick(ctxt: SysTick) {
     let elapsed = ELAPSED.borrow(&ctxt);
 
     elapsed.set(elapsed.get() + 1);
-
-    cortex_m::interrupt::free(|cs| {
-        let gpio_k = tm4c129x::GPIO_PORTK.borrow(cs);
-
-        if elapsed.get() % 100 == 0 {
-            gpio_k.data.modify(|r, w| w.data().bits(r.data().bits() ^ 0x10));
-        }
-    })
+    if elapsed.get() % 100 == 0 {
+        set_led(LED1, true);
+        set_led(LED2, false);
+    }
+    if elapsed.get() % 100 == 50 {
+        set_led(LED1, false);
+        set_led(LED2, true);
+    }
 }
 
 #[used]