希望大家帮我看看，求高手讲解一下，万分感谢

Setting REFON=1 enables the internal reference. When REF2_5V = 1, the internal reference is 2.5 V, the
reference is 1.5 V when REF2_5V = 0.
REFON=1时，如果REF2_5V=0，那么内部参考电压为1.5V,REF2_5V=1时内部参考电压为2.5V
选择外部参考电压通过SREFx，从datasheet里可以看到有很多种选择，Vref这种是内部参考电压，Veref这种是外部参考电压。

下面是一个内部温度传感器的测量程序
可以参考一下

//******************************************************************************
// MSP430G2x33/G2x53 Demo - ADC10, Sample A10 Temp and Convert to oC and oF
//
// Description: A single sample is made on A10 with reference to internal
// 1.5V Vref. Software sets ADC10SC to start sample and conversion - ADC10SC
// automatically cleared at EOC. ADC10 internal oscillator/4 times sample
// (64x) and conversion. In Mainloop MSP430 waits in LPM0 to save power until
// ADC10 conversion complete, ADC10_ISR will force exit from any LPMx in
// Mainloop on reti. Temperaure in oC stored in IntDegC, oF in IntDegF.
// Uncalibrated temperature measured from device to device will vary with
// slope and offset - please see datasheet.
// ACLK = n/a, MCLK = SMCLK = default DCO ~1.2MHz, ADC10CLK = ADC10OSC/4
//
// MSP430G2x33/G2x53
// -----------------
// /|| XIN|-
// | | |
// --|RST XOUT|-
// | |
// |A10 |
//
// D. Dang
// Texas Instruments Inc.
// December 2010
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include "msp430g2553.h"

long temp;
long IntDegF;
long IntDegC;

void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
ADC10CTL1 = INCH_10 + ADC10DIV_3; // Temp Sensor ADC10CLK/4
ADC10CTL0 = SREF_1 + ADC10SHT_3 + REFON + ADC10ON + ADC10IE;
__enable_interrupt(); // Enable interrupts.
TACCR0 = 30; // Delay to allow Ref to settle
TACCTL0 |= CCIE; // Compare-mode interrupt.
TACTL = TASSEL_2 | MC_1; // TACLK = SMCLK, Up mode.
LPM0; // Wait for delay.
TACCTL0 &= ~CCIE; // Disable timer Interrupt
__disable_interrupt();

while(1)
{
ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
__bis_SR_register(CPUOFF + GIE); // LPM0 with interrupts enabled

// oF = ((A10/1024)*1500mV)-923mV)*1/1.97mV = A10*761/1024 - 468
temp = ADC10MEM;
IntDegF = ((temp - 630) * 761) / 1024;

// oC = ((A10/1024)*1500mV)-986mV)*1/3.55mV = A10*423/1024 - 278
temp = ADC10MEM;
IntDegC = ((temp - 673) * 423) / 1024;

__no_operation(); // SET BREAKPOINT HERE
}
}

// ADC10 interrupt service routine
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR (void)
{
__bic_SR_register_on_exit(CPUOFF); // Clear CPUOFF bit from 0(SR)
}

#pragma vector=TIMER0_A0_VECTOR
__interrupt void ta0_isr(void)
{
TACTL = 0;
LPM0_EXIT; // Exit LPM0 on return
}

路过，进来看下

430寄存器里面没有设置的，都是默认值，这个参考电压的默认值就是3.3V