msp430x54x_ucs_3.c

来自「MSP430的开发程序的例子+中文注释」· C语言 代码 · 共 49 行

//******************************************************************************
//  msp430FG5438 Demo - XT2 sources SMCLK
//
//  Description: This program demonstrates using XT2 to source SMCLK
//  SMCLK = XT2 = 8MHz	
//  //* An external watch crystal between XIN & XOUT is required for ACLK *//	
//
//               msp430FG5438
//             -----------------
//        /|\ |                 |
//         |  |                 |
//         ---|RST              |
//            |                 |
//            |            XT2IN|-
//            |                 | HF XTAL (455kHz - 16MHz)
//            |           XT2OUT|-
//            |                 |
//            |            P11.2|--> SMCLK = 8MHz
//            |                 |
//
//   M Smertneck
//   Texas Instruments Inc.
//   April 2008
//   Built with CCEv3.2 IAR Embedded Workbench Version: 3.42A
//******************************************************************************

#include <msp430x54x.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                // Stop watchdog timer

  P11DIR = BIT2;                           // P11.2 to output direction
  P11SEL = BIT2;                           // P11.2 to output SMCLK
  P5SEL |= 0x0C;                           // XT2
 
  UCSCTL6 &= ~XT2DRIVE_1;

  UCSCTL4  |= SELS__XT2CLK;  
  
  while ( (SFRIFG1 &OFIFG))
  {    
    UCSCTL7 &= ~(XT2OFFG + DCOFFG);
    SFRIFG1 &= ~OFIFG;
  }
  while(1);                                 // Loop in place
}