First working program

README.md

@@ -0,0 +1,5 @@
+This program illuminates the blue LED on an STM32F0-Discovery board.
+(it's actually blinking really really fast)
+
+This is modelled afer the STM32F4 example found here:
+http://jeremyherbert.net/get/stm32f4_getting_started

src/main.c

@@ -1,4 +1,11 @@
-//#include "stm32f0xx_conf.h"
+#include "stm32f0xx_conf.h"
+
+void TIM2_IRQHandler(void) {
+  // flash on update event
+  if (TIM2->SR & TIM_SR_UIF) GPIOC->ODR ^= (1 << 8);
+   
+  TIM2->SR = 0x0; // reset the status register
+}
 
 int main(void)
 {
@@ -14,10 +21,20 @@ int main(void)
 //#define LED_ORANGE 0
 //#define LED_RED 0
 
-	RCC->AHBENR |= RCC_AHBENR_IOPCEN; // enable the clock to GPIOC
+	RCC->AHBENR |= RCC_AHBENR_GPIOCEN; 	// enable the clock to GPIOC 
+						//(RM0091 lists this as IOPCEN, not GPIOCEN)
+	RCC->APB1ENR |= RCC_APB1ENR_TIM2EN; // enable TIM2 clock
 
 	GPIOC->MODER = (1 << 16);
 	
-	while(1) GPIOC->ODR ^= (1 << 16);
+	NVIC->ISER[0] |= 1<< (TIM2_IRQn); // enable the TIM2 IRQ
+	
+	TIM2->PSC = 0x0; // no prescaler, timer counts up in sync with the peripheral clock
+	TIM2->DIER |= TIM_DIER_UIE; // enable update interrupt
+	TIM2->ARR = 0x01; // count to 1 (autoreload value 1)
+	TIM2->CR1 |= TIM_CR1_ARPE | TIM_CR1_CEN; // autoreload on, counter enabled
+	TIM2->EGR = 1; // trigger update event to reload timer registers
+	
+	while(1);
 	
 }