/**
??******************************************************************************
??*?@file????system_stm32l4xx.c
??*?@author??MCD?Application?Team
??*?@version?V1.3.2
??*?@date????16-June-2017
??*?@brief???CMSIS?Cortex-M4?Device?Peripheral?Access?layer?System?Source?File
??*
??*???This?file?provides?two?functions?and?one?global?variable?to?be?called?from
??*???user?application:
??*??????-?SystemInit（）:?This?function?is?called?at?startup?just?after?reset?and
??*??????????????????????before?branch?to?main?program.?This?call?is?made?inside
??*??????????????????????the?“startup_stm32l4xx.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.
??*
??*???After?each?device?reset?the?MSI?（4?MHz）?is?used?as?system?clock?source.
??*???Then?SystemInit（）?function?is?called?in?“startup_stm32l4xx.s“?file?to
??*???configure?the?system?clock?before?to?branch?to?main?program.
??*
??*???This?file?configures?the?system?clock?as?follows:
??*=============================================================================
??*-----------------------------------------------------------------------------
??*????????System?Clock?source????????????????????|?MSI
??*-----------------------------------------------------------------------------
??*????????SYSCLK（Hz）?????????????????????????????|?4000000
??*-----------------------------------------------------------------------------
??*????????HCLK（Hz）???????????????????????????????|?4000000
??*-----------------------------------------------------------------------------
??*????????AHB?Prescaler??????????????????????????|?1
??*-----------------------------------------------------------------------------
??*????????APB1?Prescaler?????????????????????????|?1
??*-----------------------------------------------------------------------------
??*????????APB2?Prescaler?????????????????????????|?1
??*-----------------------------------------------------------------------------
??*????????PLL_M??????????????????????????????????|?1
??*-----------------------------------------------------------------------------
??*????????PLL_N??????????????????????????????????|?8
??*-----------------------------------------------------------------------------
??*????????PLL_P??????????????????????????????????|?7
??*-----------------------------------------------------------------------------
??*????????PLL_Q??????????????????????????????????|?2
??*-----------------------------------------------------------------------------
??*????????PLL_R??????????????????????????????????|?2
??*---

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\Doc\
?????文件??????????16??2018-05-15?14:38??STM32L4_SPI_2018518132418\Doc\Description.txt
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\Library\
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\Library\CMSIS\
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\Library\CMSIS\Common\
?????文件????????4637??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\accelero.h
?????文件????????3634??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\audio.h
?????文件????????5399??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\camera.h
?????文件????????3341??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\epd.h
?????文件????????4613??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\gyro.h
?????文件????????3045??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\hsensor.h
?????文件????????6580??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\idd.h
?????文件????????5401??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\io.h
?????文件????????3590??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\lcd.h
?????文件????????3618??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\magneto.h
?????文件????????3045??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\psensor.h
?????文件???????36409??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\Release_Notes.html
?????文件????????3249??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\ts.h
?????文件????????3677??2017-12-22?11:16??STM32L4_SPI_2018518132418\Library\CMSIS\Common\tsensor.h
?????文件??????114403??2015-03-18?16:49??STM32L4_SPI_2018518132418\Library\CMSIS\core_cm4.h
?????目錄???????????0??2018-05-18?13:24??STM32L4_SPI_2018518132418\Library\CMSIS\Include\
?????文件?????1298102??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l431xx.h
?????文件?????1267951??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l432xx.h
?????文件?????1368259??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l433xx.h
?????文件?????1286405??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l442xx.h
?????文件?????1386423??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l443xx.h
?????文件?????1321438??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l451xx.h
?????文件?????1378506??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l452xx.h
?????文件?????1396670??2017-06-07?17:34??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l462xx.h
?????文件?????1452909??2017-06-16?10:17??STM32L4_SPI_2018518132418\Library\CMSIS\Include\stm32l471xx.h
............此處省略398個文件信息