STM32F4-SIM900A模块GPRS功能使用精简例程

本例程使用的是标准库，根据sim900a模块参考例程和正点原子官方例程修改而来，使复杂的官方例程精简化，并且添加注释，简单易懂，可以实现GPRS的数据传输功能。

/**
  ******************************************************************************
  * @file    misc.c
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    04-August-2014
  * @brief   This file provides all the miscellaneous firmware functions （add-on
  *          to CMSIS functions）.
  *          
  *  @verbatim   
  *                               
  *          ===================================================================      
  *                        How to configure Interrupts using driver 
  *          ===================================================================      
  * 
  *            This section provide functions allowing to configure the NVIC interrupts （IRQ）.
  *            The Cortex-M4 exceptions are managed by CMSIS functions.
  *
  *            1. Configure the NVIC Priority Grouping using NVIC_PriorityGroupConfig（）
  *                function according to the following table.
 
  *  The table below gives the allowed values of the pre-emption priority and subpriority according
  *  to the Priority Grouping configuration performed by NVIC_PriorityGroupConfig function
  *    ==========================================================================================================================
  *      NVIC_PriorityGroup   | NVIC_IRQChannelPreemptionPriority | NVIC_IRQChannelSubPriority  |       Description
  *    ==========================================================================================================================
  *     NVIC_PriorityGroup_0  |                0                  |            0-15             | 0 bits for pre-emption priority
  *                           |                                   |                             | 4 bits for subpriority
  *    --------------------------------------------------------------------------------------------------------------------------
  *     NVIC_PriorityGroup_1  |                0-1                |            0-7              | 1 bits for pre-emption priority
  *                           |                                   |                             | 3 bits for subpriority
  *    --------------------------------------------------------------------------------------------------------------------------    
  *     NVIC_PriorityGroup_2  |                0-3                |            0-3              | 2 bits for pre-emption priority
  *                           |                                   |                             | 2 bits for subpriority
  *    --------------------------------------------------------------------------------------------------------------------------    
  *     NVIC_PriorityGroup_3  |                0-7                |            0-1              | 3 bits for pre-emption priority
  *                           |                                   |                             | 1 bits for subpriority
  *    -----------------------------------------------

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2019-03-30 13:55  sim900通信--1.0\
     目录           0  2019-03-30 13:55  sim900通信--1.0\CORE\
     文件      109142  2016-04-15 21:59  sim900通信--1.0\CORE\core_cm4.h
     文件       22735  2016-04-15 21:59  sim900通信--1.0\CORE\core_cm4_simd.h
     文件       17146  2016-04-15 21:59  sim900通信--1.0\CORE\core_cmFunc.h
     文件       20513  2016-04-15 21:59  sim900通信--1.0\CORE\core_cmInstr.h
     文件       29605  2016-04-15 21:59  sim900通信--1.0\CORE\startup_stm32f40_41xxx.s
     目录           0  2019-03-30 13:55  sim900通信--1.0\FWLIB\
     目录           0  2019-03-30 13:55  sim900通信--1.0\FWLIB\inc\
     文件        6924  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\misc.h
     文件       32880  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_adc.h
     文件       27318  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_can.h
     文件        2416  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_crc.h
     文件       14481  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_cryp.h
     文件       14946  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_dac.h
     文件        4296  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_dbgmcu.h
     文件       12977  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_dcmi.h
     文件       28882  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_dma.h
     文件       19692  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_dma2d.h
     文件        8012  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_exti.h
     文件       24467  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_flash.h
     文件        3275  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_flash_ramfunc.h
     文件       44924  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_fmc.h
     文件       27181  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_fsmc.h
     文件       23548  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_gpio.h
     文件       10084  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_hash.h
     文件       31939  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_i2c.h
     文件        4323  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_iwdg.h
     文件       21191  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_ltdc.h
     文件        7728  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_pwr.h
     文件       30063  2016-04-15 21:59  sim900通信--1.0\FWLIB\inc\stm32f4xx_rcc.h
............此处省略167个文件信息