fet120_rosc.c

来自「一个基于TI的MSP430的程序设计参考代码」· C语言 代码 · 共 47 行

//******************************************************************************
//  MSP-FET430P120 Demo - BasicClock DCOCLK Biased with External Resistor Rosc
//    
//  Description; Use external resistor on P2.5 as DCO current source. DCOCLK 
//  is used by default as the MCLK source. Mainloop drives a 10 cycle software 
//  loop toggling P1.1. Measure DCOCLK/10 on P1.1. Example also disables XTAL 
//  buffer. Use of external resistor reduces temperature sensitivity of DCOCLK.
//
//  DCOCLK = Using default DCO and RSEL values @ 2.85V
//  022k ~ 5.5MHz
//  100k ~ 2Mhz
//  220k ~ 860kHz
//  470k ~ 400kHz
//
//               MSP430F123(2)
//            -----------------
//   /|\  /|\|              XIN|-  
//    |    | |                 | 
//    R    --|RST          XOUT|-
//    |      |                 |
//    -------|P2.5/ROSC    P1.1|-->DCOCLK/10
//
//  M.Buccini
//  Texas Instruments, Inc
//  September 2003
//  Built with IAR Embedded Workbench Version: 1.26B
//  December 2003
//  Updated for IAR Embedded Workbench Version: 2.21B
//******************************************************************************

#include  "msp430x12x.h"

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;             // Stop WDT
  P1DIR |= 0x02;                        // P1.1 = output direction
  BCSCTL2 |= DCOR;                      // Rosc
  _BIS_SR(OSCOFF);                      // XTAL not used


  while(1)
  {
    P1OUT |= 0x02;                      
    P1OUT &= ~0x02;                     
  }
}