msp430x21x2_compa_01.c

MSP430的开发程序的例子+中文注释

//******************************************************************************
//  MSP430x21x2 Demo - Comparator A, Poll input CA0, result in P1.0
//
//   Description: The Voltage at pin CA0 (Vcompare) is compared with reference
//   voltage of 0.5*Vcc. LED is toggled when Vcompare crosses the ref voltage.
//
//
//                MSP430x21x2
//             -----------------
//         /|\|                 |
//          | |                 |
//          --|RST      P2.3/CA0|<--Vcompare
//            |                 |
//         <--|CAOUT/P2.2       |
//            |             P1.0|-->LED
//
//  P. Thanigai / K.Venkat
//  Texas Instruments Inc.
//  November 2007
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include  <msp430x21x2.h>

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

  CACTL1 = CAON+CAREF_2+CARSEL;             // Enable Comp, ref = 0.5*Vcc
  CACTL2 = P2CA0;                           // Pin to CA0
  P1DIR |= BIT0;                            // P1.0 = output direction
  P2SEL |= BIT2;                            // P2.2 = CAOUT
  while(1)
    if (CAOUT&CACTL2)
      P1OUT |= 0x01;                       // Set LED if result =1
    else
      P1OUT &= ~0x01;                      // Clear LED if result =0
}