add opportunity protect flash from reading and settings system clock 50 MHz

stm32/system/stm32f4xx.h

@@ -95,7 +95,8 @@
   */           
 
 #if !defined  (HSE_VALUE) 
-  #define HSE_VALUE    ((uint32_t)25000000) /*!< Value of the External oscillator in Hz */
+ #define HSE_VALUE    ((uint32_t)25000000) /*!< Value of the External oscillator in Hz */
+//#define HSE_VALUE    ((uint32_t)50000000) /*!< Value of the External oscillator in Hz */
 #endif /* HSE_VALUE */
 
 /**

stm32/system/system_stm32f4xx.c

@@ -152,7 +152,7 @@
 
 /************************* PLL Parameters *************************************/
 /* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N */
-#define PLL_M      25
+#define PLL_M     25//50//
 #define PLL_N      336
 
 /* SYSCLK = PLL_VCO / PLL_P */

user/main.c

@@ -46,6 +46,15 @@ int main()
 	FLASH_ClearFlag(FLASH_FLAG_PGPERR);
 	FLASH_ClearFlag(FLASH_FLAG_PGSERR);
 
+/*	if (FLASH_OB_GetRDP() != SET) {
+		FLASH_Unlock();                           // this line is critical!
+		FLASH_OB_Unlock();
+		FLASH_OB_RDPConfig(OB_RDP_Level_1);
+		FLASH_OB_Launch();                        // Option Bytes programming
+		FLASH_OB_Lock();
+		FLASH_Lock();
+	}*/
+
 	gpio_init();
 
 	WDG_Init();