ADD: priority grouping configuration, interrupts priorities definitions

Makefile

@@ -1,6 +1,6 @@
 # General Target Settings
 TARGET	= bluepill-serial-monster
-SRCS	= main.c system_clock.c status_led.c usb_core.c usb_descriptors.c\
+SRCS	= main.c system_clock.c system_interrupts.c status_led.c usb_core.c usb_descriptors.c\
 	usb_io.c usb_uid.c usb_panic.c usb_cdc.c cdc_shell.c gpio.c device_config.c
 
 # Toolchain & Utils

main.c

@@ -6,13 +6,15 @@
 
 #include <stm32f1xx.h>
 #include "system_clock.h"
+#include "system_interrupts.h"
 #include "status_led.h"
 #include "device_config.h"
 #include "usb.h"
 
 
 int main() {
     system_clock_init();
+    system_interrupts_init();
     device_config_init();
     status_led_init();
     usb_init();

system_interrupts.c

@@ -0,0 +1,5 @@
+#include "system_interrupts.h"
+
+void system_interrupts_init() {
+    NVIC_SetPriorityGrouping(SYSTEM_INTERRUPTS_PRIORITY_GROUPING);
+}

system_interrupts.h

@@ -0,0 +1,12 @@
+#ifndef SYSTEM_INTERRUPTS_H
+#define SYSTEM_INTERRUPTS_H
+
+#include <stm32f1xx.h>
+
+#define SYSTEM_INTERRUPTS_PRIORITY_GROUPING     0x02 /* 2 bits preemption, 2 bits sub-priority */
+#define SYSTEM_INTERRUTPS_PRIORITY_CRITICAL     (NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 0, 0))
+#define SYSTEM_INTERRUTPS_PRIORITY_BASE         (NVIC_EncodePriority(NVIC_GetPriorityGrouping(), 2, 0))
+
+void system_interrupts_init();
+
+#endif /*  SYSTEM_INTERRUPTS_H */