/**
??******************************************************************************
??*?@file????system_stm32f4xx.c
??*?@author??MCD?Application?Team
??*?@version?V1.6.1
??*?@date????21-October-2015
??*?@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(shí)間???名稱(chēng)
-----------?---------??----------?-----??----
?????目錄???????????0??2016-05-22?16:20??CMSIS\
?????目錄???????????0??2016-05-22?16:20??CMSIS\DSP_Lib\
?????目錄???????????0??2016-05-22?16:20??CMSIS\DSP_Lib\Source\
?????目錄???????????0??2016-05-22?16:20??CMSIS\DSP_Lib\Source\BasicMathFunctions\
?????文件????????5113??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_abs_f32.c
?????文件????????5457??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_abs_q15.c
?????文件????????4430??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_abs_q31.c
?????文件????????5091??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_abs_q7.c
?????文件????????4890??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_add_f32.c
?????文件????????4422??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_add_q15.c
?????文件????????4552??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_add_q31.c
?????文件????????4225??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_add_q7.c
?????文件????????4612??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_dot_prod_f32.c
?????文件????????4911??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_dot_prod_q15.c
?????文件????????4999??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_dot_prod_q31.c
?????文件????????5407??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_dot_prod_q7.c
?????文件????????5581??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_mult_f32.c
?????文件????????5303??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_mult_q15.c
?????文件????????5200??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_mult_q31.c
?????文件????????4529??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_mult_q7.c
?????文件????????4573??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_negate_f32.c
?????文件????????4620??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_negate_q15.c
?????文件????????4177??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_negate_q31.c
?????文件????????4103??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_negate_q7.c
?????文件????????5094??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_offset_f32.c
?????文件????????4533??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_offset_q15.c
?????文件????????4424??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_offset_q31.c
?????文件????????4461??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_offset_q7.c
?????文件????????5647??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_scale_f32.c
?????文件????????5504??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_scale_q15.c
?????文件????????7053??2015-10-01?01:14??CMSIS\DSP_Lib\Source\BasicMathFunctions\arm_scale_q31.c
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