I2S——MP3播放器

利用stm32f407和SD卡， 通过i2s协议做一个MP3播放器。

/**
  ******************************************************************************
  * @file    system_stm32f4xx.c
  * @author  MCD Application Team
  * @version V1.8.0
  * @date    09-November-2016
  * @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）                     

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2017-05-09 17:46  I2S—MP3播放器\
     目录           0  2015-10-31 15:19  I2S—MP3播放器\Doc\
     文件         401  2017-03-19 12:42  I2S—MP3播放器\keilkill.bat
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Include\
     文件      940127  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Include\stm32f4xx.h
     文件        2235  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Include\system_stm32f4xx.h
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\
     文件       25819  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f401xx.s
     文件       29696  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f40xx.s
     文件       29607  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f40_41xxx.s
     文件       19189  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f410xx.s
     文件       26519  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f411xe.s
     文件       21484  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f412xg.s
     文件       23401  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f413_423xx.s
     文件       31056  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f427x.s
     文件       30981  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f427_437xx.s
     文件       31136  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f429_439xx.s
     文件       22148  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f446xx.s
     文件       30929  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\startup_stm32f469_479xx.s
     文件         135  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\arm\说明.txt
     文件       61020  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\system_stm32f4xx.c
     文件         141  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Device\ST\STM32F4xx\Source\Templates\说明.txt
     目录           0  2017-05-09 17:45  I2S—MP3播放器\Libraries\CMSIS\Include\
     文件        7253  2017-03-19 12:42  I2S—MP3播放器\Libraries\CMSIS\Include\arm_common_tables.h
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