added external interrupt example

atochukwu0 · Mar 19, 2017 · 1c4cf72 · 1c4cf72
1 parent 7469fa4
commit 1c4cf72
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Showing 4 changed files with 619 additions and 3 deletions.
diff --git a/clock/clock.c b/clock/clock.c
@@ -129,17 +129,16 @@ void set_system_clock_to_25Mhz(void)
 
 /*
  * By default 8 MHz internal clock is used (HSI)
- * Set up as 72 MHz
+ * Set up as 72 MHz (HSE-PLL)
  *
+ * 25M ->   /5    ->   *8    ->   /5    ->   *9   -> 72 MHz
  * HSE -> PreDiv2 -> Pll2Mul -> PreDiv1 -> PllMul -> System Clock
  * Set Prediv1Src = PLL2, Set PllSrc as Prediv1
  *
  * 25 MHz External clock is selected as the source clock (HSE)
  * It is divided by 5 with PreDiv2, then muliplied by 8 with Pll2Mul
  * Then it is divided by 5 with PreDiv1, then multiplied by 9 with PllMul
  * Then choose Pll as the clock source
- *
- * 25Mhz / 5 * 8 / 5 * 9 = 72 MHz
  */
 void set_system_clock_to_72Mhz(void)
 {