tmp

examples/bare5.rs

@@ -119,17 +119,20 @@ fn wait(i: u32) {
     }
 }
 
+// system startup, can be hidden from the user
 fn main() {
-    // power on GPIOA, RM0368 6.3.11
-    let rcc = RCC::get(); // get the reference to RCC in memory
-    unsafe {
+    let rcc = unsafe { &mut *RCC::get() }; // get the reference to RCC in memory
+    let gpioa = unsafe { &mut *GPIOA::get() }; // get the reference to GPIOA in memory
+    idle(rcc, gpioa);
+}
+
+// user application
+fn idle(rcc: &mut RCC, gpioa: &mut GPIOA) {
+    // power on GPIOA
     let r = (*rcc).AHB1ENR.read(); // read
     (*rcc).AHB1ENR.write(r | 1 << (0)); // set enable
-    }
 
-    // configure PA5 as output, RM0368 8.4.1
-    let gpioa = GPIOA::get(); // get the reference to GPIOA in memory
-    unsafe {
+    // configure PA5 as output
     let r = (*gpioa).MODER.read() & !(0b11 << (5 * 2)); // read and mask
     (*gpioa).MODER.write(r | 0b01 << (5 * 2)); // set output mode
 
@@ -137,16 +140,25 @@ fn main() {
     // this is more efficient as the read register is not needed.
 
     loop {
-            // set PA5 high, RM0368 8.4.7
+        // set PA5 high
         (*gpioa).BSRRH.write(1 << 5); // set bit, output hight (turn on led)
         wait(10_000);
 
-            // set PA5 low, RM0368 8.4.7
+        // set PA5 low
         (*gpioa).BSRRL.write(1 << 5); // clear bit, output low (turn off led)
         wait(10_000);
     }
 }
-}
+
+// 1. C like API
+// In C the .h files are used for defining interfaces, like function signatures (prototypes),
+// structs and macros (but usually not the functions themselves)
+// here is a peripheral abstraction quite similar to what you would find in the .h files
+// provided by ST (and other companies). Actually, the file presesnted here is mostly a
+// cut/paste/replace of the stm32f40x.h, just Rustified.
+//
+// Here all peripheral access is unsafe, (as we are dereferencing raw pointers). In the code
+// we have fairly large unsafe blocks. Your task here is to
 
 // As we are not using interrupts, we just register a dummy catch all handler
 #[link_section = ".vector_table.interrupts"]