hi,
//******************************************************************************
// MSP430G2x13/G2x53 Demo - Comp_A, Output Reference Voltages on P1.1
//
// Description: Output Comparator_A reference levels on P1.1. Program will
// cycle through the on-chip comparator_A reference voltages with output on
// P1.1. Normal mode is LPM0, TA0_ISR will interrupt LPM0.
// ACLK = n/a, MCLK = SMCLK = default DCO
//
// MSP430G2x13/G2x53
// -----------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P1.1/CA1|--> Vref
// | |
//
// D. Dang
// Texas Instruments Inc.
// December 2010
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430g2553.h>
//void delay(void); // Software delay
void main (void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
CACTL2 = P2CA4; // CA1/P1.1 = +comp
CCTL0 = CCIE; // CCR0 interrupt enabled
TACTL = TASSEL_2 + ID_3 + MC_2; // SMCLK/8, cont-mode
_EINT(); // enable interrupts
while (1) // Loop
{
CACTL1 = 0x00; // No reference voltage
_BIS_SR(LPM0_bits); // Enter LPM0
CACTL1 = CAREF0 + CAON; // 0.25*Vcc, Comp. on
_BIS_SR(LPM0_bits); // Enter LPM0
CACTL1 = CAREF1 + CAON; // 0.5*Vcc, Comp. on
_BIS_SR(LPM0_bits); // Enter LPM0
CACTL1 = CAREF1 + CAREF0 + CAON; // 0.55V, Comp. on
_BIS_SR(LPM0_bits); // Enter LPM0
}
}
// Timer A0 interrupt service routine
#pragma vector=TIMER0_A0_VECTOR
__interrupt void Timer_A (void)
{
_BIC_SR_IRQ(LPM0_bits); // Clear LPM0 bits from 0(SR)
}
this is the example code from ti for comparator. it says on p1.1 we get the reference voltages: no ref, 0.25*vcc, 0.5*vcc, 0.55v.
that is it should have been: 0v, 0.25*3.6=0.9v, 0.5*3.6=1.8v, 0.55v.
but i get 3.6v, 3.24v,3.36v, 1v respectively on p1.1. so please help me out to solve this ambiguity .
