/**
??******************************************************************************
??*?@file????system_stm32f4xx.c
??*?@author??MCD?Application?Team
??*?@version?V1.4.0
??*?@date????04-August-2014
??*?@brief???CMSIS?Cortex-M4?Device?Peripheral?Access?layer?System?Source?File.
??*??????????This?file?contains?the?system?clock?configuration?for?STM32F4xx?devices.
??*?????????????
??*?1.??This?file?provides?two?functions?and?one?global?variable?to?be?called?from?
??*?????user?application:
??*??????-?SystemInit（）:?Setups?the?system?clock?（System?clock?source?PLL?Multiplier
??*??????????????????????and?Divider?factors?AHB/APBx?prescalers?and?Flash?settings）
??*??????????????????????depending?on?the?configuration?made?in?the?clock?xls?tool.?
??*??????????????????????This?function?is?called?at?startup?just?after?reset?and?
??*??????????????????????before?branch?to?main?program.?This?call?is?made?inside
??*??????????????????????the?“startup_stm32f4xx.s“?file.
??*
??*??????-?SystemCoreClock?variable:?Contains?the?core?clock?（HCLK）?it?can?be?used
??*??????????????????????????????????by?the?user?application?to?setup?the?SysTick?
??*??????????????????????????????????timer?or?configure?other?parameters.
??*?????????????????????????????????????
??*??????-?SystemCoreClockUpdate（）:?Updates?the?variable?SystemCoreClock?and?must
??*?????????????????????????????????be?called?whenever?the?core?clock?is?changed
??*?????????????????????????????????during?program?execution.
??*
??*?2.?After?each?device?reset?the?HSI?（16?MHz）?is?used?as?system?clock?source.
??*????Then?SystemInit（）?function?is?called?in?“startup_stm32f4xx.s“?file?to
??*????configure?the?system?clock?before?to?branch?to?main?program.
??*
??*?3.?If?the?system?clock?source?selected?by?user?fails?to?startup?the?SystemInit（）
??*????function?will?do?nothing?and?HSI?still?used?as?system?clock?source.?User?can?
??*????add?some?code?to?deal?with?this?issue?inside?the?SetSysClock（）?function.
??*
??*?4.?The?default?value?of?HSE?crystal?is?set?to?25MHz?refer?to?“HSE_VALUE“?define
??*????in?“stm32f4xx.h“?file.?When?HSE?is?used?as?system?clock?source?directly?or
??*????through?PLL?and?you?are?using?different?crystal?you?have?to?adapt?the?HSE
??*????value?to?your?own?configuration.
??*
??*?5.?This?file?configures?the?system?clock?as?follows:
??*=============================================================================
??*=============================================================================
??*????????????????????Supported?STM32F40xxx/41xxx?devices
??*-----------------------------------------------------------------------------
??*????????System?Clock?source????????????????????|?PLL?（HSE）
??*-----------------------------------------------------------------------------
??*????????SYSCLK（Hz）?????????????????????????????|?168000000
??*-----------------------------------------------------------------------------
??*????????HCLK（Hz）???????????????????????

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2018-06-25?09:21??整合\cmsis\
?????文件????????4676??2014-07-17?21:52??整合\cmsis\arm_common_tables.h
?????文件????????3666??2014-07-17?21:52??整合\cmsis\arm_const_structs.h
?????文件??????242444??2014-07-17?21:52??整合\cmsis\arm_math.h
?????文件???????33042??2014-07-17?21:52??整合\cmsis\core_cm0.h
?????文件???????40429??2014-07-17?21:52??整合\cmsis\core_cm0plus.h
?????文件???????99832??2014-07-17?21:52??整合\cmsis\core_cm3.h
?????文件??????109142??2014-07-17?21:52??整合\cmsis\core_cm4.h
?????文件???????22735??2014-07-17?21:52??整合\cmsis\core_cm4_simd.h
?????文件???????17146??2014-07-17?21:52??整合\cmsis\core_cmFunc.h
?????文件???????20513??2014-07-17?21:52??整合\cmsis\core_cmInstr.h
?????文件???????41744??2014-07-17?21:52??整合\cmsis\core_sc000.h
?????文件???????98211??2014-07-17?21:52??整合\cmsis\core_sc300.h
?????文件???????29605??2014-08-02?00:12??整合\cmsis\startup_stm32f40_41xxx.s
?????文件??????704095??2014-08-01?22:30??整合\cmsis\stm32f4xx.h
?????文件???????47782??2014-08-02?00:06??整合\cmsis\system_stm32f4xx.c
?????文件????????2233??2014-08-01?22:30??整合\cmsis\system_stm32f4xx.h
?????目錄???????????0??2018-06-25?09:21??整合\DebugConfig\
?????文件????????2084??2015-10-27?12:06??整合\DebugConfig\led_STM32F407ZG.dbgconf
?????文件????????1527??2015-10-27?12:06??整合\DebugConfig\led_STM32F411CEUx.dbgconf
?????目錄???????????0??2018-06-25?09:21??整合\list\
?????文件??????125062??2018-06-08?10:26??整合\list\lstm32.map
?????文件???????77096??2018-06-08?10:25??整合\list\startup_stm32f40_41xxx.lst
?????文件??????142284??2018-06-08?14:24??整合\lstm32.uvguix.Administrator
?????文件???????73010??2017-11-15?21:10??整合\lstm32.uvguix.Lenovo
?????文件???????72110??2017-05-11?20:50??整合\lstm32.uvguix.Sh
?????文件???????12904??2018-01-14?15:53??整合\lstm32.uvoptx
?????文件???????18775??2018-01-14?15:53??整合\lstm32.uvprojx
?????目錄???????????0??2018-06-25?09:21??整合\obj\
?????文件??????262036??2017-03-01?11:21??整合\obj\beep.crf
?????文件?????????349??2017-03-01?11:21??整合\obj\beep.d
............此處省略103個文件信息