TI官方的提供的代码

/* --COPYRIGHT--,BSD_EX

 * Copyright (c) 2012, Texas Instruments Incorporated

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * *  Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 *

 * *  Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * *  Neither the name of Texas Instruments Incorporated nor the names of

 *    its contributors may be used to endorse or promote products derived

 *    from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,

 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 *******************************************************************************

 * 

 *                       MSP430 CODE EXAMPLE DISCLAIMER

 *

 * MSP430 code examples are self-contained low-level programs that typically

 * demonstrate a single peripheral function or device feature in a highly

 * concise manner. For this the code may rely on the device's power-on default

 * register values and settings such as the clock configuration and care must

 * be taken when combining code from several examples to avoid potential side

 * effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware

 * for an API functional library-approach to peripheral configuration.

 *

 * --/COPYRIGHT--*/

//******************************************************************************

//  MSP-FET430P140 Demo - Basic Clock, Output Buffered SMCLK, ACLK and MCLK

//

//  Description: Output buffered MCLK, SMCLK and ACLK.

//  ACLK = LFXT1 = 32768, MCLK = DCO Max, SMCLK = XT2

//  //* XTAL's REQUIRED - NOT INSTALLED ON FET *//

//  //* Min Vcc required varies with MCLK frequency - refer to datasheet *//

//

//                MSP430F149

//            -----------------

//        /||              XIN|-

//         | |                 | 32k

//         --|RST          XOUT|-

//           |                 |

//           |            XT2IN|-

//           |                 | XTAL (455k - 8Mhz)

//           |RST        XT2OUT|-

//           |                 |

//           |             P5.4|-->MCLK = DCO Max

//           |             P5.5|-->SMCLK = XT2

//           |             P5.6|-->ACLK = 32kHz

//

//  M. Buccini

//  Texas Instruments Inc.

//  Feb 2005

//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.21A

//******************************************************************************

#include

MCLK由XT2CLK或者DCOCLK或者LFXT1CLK提供；主要设置SELMx；

SMCLK由XT2CLK或者DCOCLK提供；主要设置SELS；

寄存器说明

配置好时钟主要看懂以下5个寄存器就好，算是比较容易了，刚开始比较麻烦，后来看了带锁频器的F5438A有9个寄存器来控制时钟系统，突然觉得这个还是可以接受的，哭脸一个.

上面的注意有一个复位是用POR不是PUC；

DCOCTL是调制DCOCLK时钟源的频率的（所以说，这个是个可调频率的振荡器，不是市面上卖的那种，是多少就是多少那种）；对定时要求不是特别严格的，可以直接用默认的就好；

DCOx主调

MODx微调

1&2就是开始做选择了，时钟的分频呀啥啥啥的，哎，其实还好，比5.1稍稍麻烦一点点而已

两个中断相关寄存器。中断使能位和中断标志位。

两个寄存器目前用到了这两位，就先写出这两位，其他位其实是有东西的