test44x_ca02.c

来自「WDT」· C语言 代码 · 共 42 行

//******************************************************************************
//   MSP430-TEST44X Demo - Comp_A Detect theashold, Set P5.1 if P1.6 > 0.25*Vcc 
//
//   Description; Use comparator_A to detect a voltage threshold.
//   Using an external potentiometer, an unknown voltage is applied to P1.6.
//   Comparator_A compares the unknown voltage to an internal reference
//   voltage, in this example 0.25*VCC.  If the unknown voltage is higher
//   than 0.25*VCC, P5.1 is set, if not, P5.1 is reset.
//   
//          MSP430F449
//       _________________
//   /|\ |            XIN|-  
//    |  |               | 
//    ---|RST        XOUT|-
//    |  |               |
//    R<-|P1.6       P5.1|-->LED
//    |  |               |           
//    ---|VSS
//
//  Yang Rui
//  Lierda, Inc
//  MAY 2004
//  Built with IAR Embedded Workbench Version: 1.26B
//******************************************************************************

#include  "msp430x44x.h"

void main (void)
{
  WDTCTL = WDTPW + WDTHOLD;       // Stop WDT
  P5DIR |= BIT1;                  // P5.1 output
  CACTL1 = CARSEL + CAREF0 + CAON;   // 0.25 Vcc = -comp, on
  CACTL2 = P2CA0;                 // P1.6 = +comp

  while (1)                       // Test comparator_A output
  {
    if ((CAOUT & CACTL2) == CAOUT) P1OUT |= BIT0;   // if CAOUT set, set P5.1
    else P5OUT &= ~BIT1;          // else reset
  }
}