[参考译文] MSP430FR6047：我尝试从 P2.2 (定制板)读取 ADC 电压。 我的 ADC 值从2048 12位分辨率开始。 不会下降到低于该值。

#include <msp430.h>

unsigned int ADC_value;

void UART_sendData(char data) {
    while (!(UCA3IFG & UCTXIFG)); // Wait for TX buffer to be ready
    UCA3TXBUF = data;
}

void UART_sendString(char *str) {
    while (*str != '\0') {
        UART_sendData(*str++);
    }
}

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer

    P2SEL1 |= BIT2;             // Configure P2.2 for ADC
    P2SEL0 |= BIT2;

    PM5CTL0 &= ~LOCKLPM5;       // Unlock I/O pins

    // Configure internal voltage reference
     while (REFCTL0 & REFGENBUSY);   // If reference generator busy, WAIT
    REFCTL0 |= REFVSEL_1 | REFON;  // Select internal ref = 2.5V, Reference ON

    // Configure ADC
    ADC12CTL0 &= ~ADC12SHT0;
    ADC12CTL0 |= ADC12SHT0_2;  // 16 ADC12CLK cycles
    ADC12CTL0 |= ADC12ON;       // Turn on ADC12
    ADC12CTL1 |= ADC12SSEL_2 | ADC12SHP;  // SMCLK, sample-and-hold mode
    ADC12CTL2 &= ~ADC12RES_2;   // Clear resolution bits
    ADC12CTL2 |= ADC12RES_2;    // 12-bit conversion resolution
    ADC12MCTL0 |= ADC12INCH_14; // Channel A14 (P2.2)
    ADC12CTL0 &= ~ADC12VRSEL_2; // Clear previous reference voltage selection
   // ADC12CTL0 |= ADC12VRSEL_2;  // Select AVCC as Vref+ and AVSS as Vref-
    ADC12IER0 |= ADC12IE0;      // Enable ADC interrupt

    // UART initialization
    P8SEL0 |= BIT2 | BIT3;      // Configure P8.2 and P8.3 for UART
    P8SEL1 &= ~(BIT2 | BIT3);
    UCA3CTLW0 |= UCSWRST;       // Put UART module in reset state
    UCA3CTLW0 |= UCSSEL__SMCLK; // Select SMCLK as the clock source
    UCA3BR0 = 104;               // Set Baud rate to 9600 (assuming SMCLK is 1MHz)
    UCA3MCTLW = 0x2000;          // Set modulation (UCBRSx = 4, UCBRFx = 1, UCOS16 = 0)
    UCA3BR1 = 0;
    UCA3CTLW0 &= ~UCSWRST;       // Clear UCSWRST

    __enable_interrupt();       // Enable global interrupts

    while (1)
    {
        ADC12CTL0 |= ADC12ENC | ADC12SC;  // Start conversion
    }
}

// ADC ISR
#pragma vector = ADC12_VECTOR
__interrupt void ADC12_ISR(void)
{
    ADC_value = ADC12MEM0;      // Read ADC value

    // Convert ADC value to voltage
    float voltage = (ADC_value * ADC12VRSEL_2) / 4095.0;

    // Transmit voltage value via UART
    char voltage_str[10];
    int wholePart = (int)(voltage);
    int decimalPart = (int)((voltage - wholePart) * 1000);
    voltage_str[0] = (wholePart / 10) + '0';
    voltage_str[1] = (wholePart % 10) + '0';
    voltage_str[2] = '.';
    voltage_str[3] = (decimalPart / 100) + '0';
    voltage_str[4] = ((decimalPart / 10) % 10) + '0';
    voltage_str[5] = (decimalPart % 10) + '0';
    voltage_str[6] = 'V';
    voltage_str[7] = '\n';
    voltage_str[8] = '\r';
    voltage_str[9] = '\0';

    UART_sendString(voltage_str);
   __delay_cycles(200000);
    ADC12IFGR0 &= ~ADC12IFG0;   // Clear interrupt flag
}

浮动电压=(ADC_value * ADC12VRSEL_2)/ 4095.0；


我得到2.75V 的读数