Arduino学习——Arduino main 函数

在Arduino IDE的安装目录下可以找到main.cpp这个代码模板文件，main函数就位于此。

文件位置：{Arduino安装目录}\hardware\arduino\avr\cores\arduino\main.cpp，内容如下：
/*
  main.cpp - Main loop for Arduino sketches
  Copyright (c) 2005-2013 Arduino Team.  All right reserved.

This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <Arduino.h>

// Declared weak in Arduino.h to allow user redefinitions.
int atexit(void (* /*func*/ )()) { return 0; }

// Weak empty variant initialization function.
// May be redefined by variant files.
void initVariant() __attribute__((weak));
void initVariant() { }

void setupUSB() __attribute__((weak));
void setupUSB() { }

int main(void)
{
    init();        //硬件初始化

initVariant();  //特有硬件初始化。因为不同的开发板有自己独特的初始化逻辑。

#if defined(USBCON)
    USBDevice.attach();
#endif
   
    setup();
   
    for (;;) {
        loop();
        if (serialEventRun) serialEventRun();
    }
        
    return 0;
}