Add firmware wireframe

src/system.c

@@ -0,0 +1,23 @@
+#include <stdint.h>
+#include "stm32f030x6.h"
+
+void SystemInit(void)
+{
+    // Activate HSI and wait for it to be ready
+    RCC->CR = RCC_CR_HSION;
+    while(!(RCC->CR & RCC_CR_HSIRDY));
+
+    // Set PLL to x12 (-> 48MHz system clock)
+    RCC->CFGR = RCC_CFGR_PLLMUL_3 | RCC_CFGR_PLLMUL_1;
+
+    // Activate PLL and wait
+    RCC->CR |= RCC_CR_PLLON;
+    while(!(RCC->CR & RCC_CR_PLLRDY));
+
+    // Select PLL as clock source
+    RCC->CFGR = RCC_CFGR_PLLMUL_3 | RCC_CFGR_PLLMUL_1 | RCC_CFGR_SW_1;
+
+    // Disable all interrupts
+    RCC->CIR = 0x00000000;
+}
+