msp430xg46x_hfxt2.c

来自「TI提供的MSP430开发例程,适合初学者练习各个功能模块的使用」· C语言 代码 · 共 54 行

//******************************************************************************
//   MSP430xG46x Demo - FLL+, MCLK Configured to Operate from XT2 HF XTAL
//
//   Description: Proper selection of an external HF XTAL for MCLK is
//   demonstrated using HF XT2 OSC.  OFIFG is polled until the HF XTAL
//   is stable - only then is MCLK sourced by XT2.  MCLK is buffered on P1.1.
//   //** HF XTAL NOT INSTALLED ON FET **//
//
//                MSP430xG46x
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//            |                 |
//            |            XT2IN|-
//            |                 | HF XTAL (455kHz - 8MHz)
//            |           XT2OUT|-
//            |                 |
//            |                 |
//            |        P1.1/MCLK|-->MCLK = HF XTAL
//
//  K. Quiring/ M. Mitchell
//  Texas Instruments Inc.
//  October 2006
//  Built with IAR Embedded Workbench Version: 3.41A
//******************************************************************************
#include  <msp430xG46x.h>

void main(void)
{
  volatile unsigned int i;

  WDTCTL = WDTPW+WDTHOLD;                   // Stop WDT
  _BIS_SR(OSCOFF + SCG0 + GIE);             // Disable LFXT1 xtal osc & FLL loop

  FLL_CTL1 &= ~XT2OFF;                      // Activate XT2 high freq xtal

  // Wait for xtal to stabilize
  do
  {
  IFG1 &= ~OFIFG;                           // Clear OSCFault flag
  for (i = 5; i > 0; i--);                  // Time for flag to set
  }
  while ((IFG1 & OFIFG));                   // OSCFault flag still set?

  FLL_CTL1 |= SELM1;                        // MCLK = XT2

  P1DIR |= 0x002;                           // P1.1 output direction
  P1SEL |= 0x002;                           // P1.1 option select

  while(1);
}