/**
??******************************************************************************
??*?@file????system_stm32l4xx.c
??*?@author??MCD?Application?Team
??*?@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
-----------?---------??----------?-----??----

?????文件???????6967??2018-03-09?10:20??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\.mxproject

?????文件????1149397??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l431xx.h

?????文件????1129024??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l432xx.h

?????文件????1218315??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l433xx.h

?????文件????1145477??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l442xx.h

?????文件????1234768??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l443xx.h

?????文件????1171444??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l451xx.h

?????文件????1229031??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l452xx.h

?????文件????1245484??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l462xx.h

?????文件????1292816??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l471xx.h

?????文件????1422301??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l475xx.h

?????文件????1433632??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l476xx.h

?????文件????1438754??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l485xx.h

?????文件????1450085??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l486xx.h

?????文件????1535226??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l496xx.h

?????文件????1558979??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4a6xx.h

?????文件????1567835??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4r5xx.h

?????文件????1605362??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4r7xx.h

?????文件????1833718??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4r9xx.h

?????文件????1592257??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4s5xx.h

?????文件????1629784??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4s7xx.h

?????文件????1858140??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4s9xx.h

?????文件???????8691??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\stm32l4xx.h

?????文件???????3874??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Include\system_stm32l4xx.h

?????文件??????18826??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l431xx.s

?????文件??????18504??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l432xx.s

?????文件??????18989??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l433xx.s

?????文件??????18593??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l442xx.s

?????文件??????19078??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l443xx.s

?????文件??????19313??2017-12-13?13:42??03-基于NB-IOT的GPS定位，數據上報云平臺\NB_GPS\Drivers\CMSIS\Device\ST\STM32L4xx\Source\Templates\arm\startup_stm32l451xx.s

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