16F1782 adc只有2V范围

Heloi正在读取一个电位器上的电压，从一个电位计到VDD，5V。我的代码是为4.096V基准和12bit ADC建立的。结果是正确的只有2V。如果电位计在0V，ADC读数6，那么高达2V，这是非常准确的。可能要读取5V，我必须配置TH。我尝试过VDREVDD，但是直到2V才得到正确的结果。我在其他项目上使用了10位ADC，并且我总是可以读取到5V的紧张，没有问题。我的代码是：



      以下为原文

    Hello
I'm reading the voltage on A0 from a potentiometer hocked up to VDD, 5V.

My code is set-up for 4.096V reference and 12bit ADC.
The results are correct up to only 2V. If the potentiometer is at 0V the ADC reads -6, then up to 2V it is very accurate.
Probably to read 5V I would have to configure the VREF to VDD what I tried,  but I get correct results only until 2V.
I used on other projects 10bit ADC and I always could read tensions up to 5V without problems.

My code is:

void main(void) {

    init();

    while (1) {
        
     ADCON0 = 0b00000001; // AN_0,
        
     GO_nDONE = 1; // Initializes A/D conversion
   
     __delay_us(50);
   
    while(GO_nDONE); // Waiting for conversion to complete
    int result = ((ADRESH<<8)+ADRESL);
    }
}

void init() {

    TRISC = 0b00000000; // all out
    TRISA = 0b00000001; // RA0 analog in, rest out.
    ANSELA = 0b00000001; // Select A0.
   
    FVRCON = 0b10000011; // FVR enabled, FVR 4.096V
    ADCON0 = 0b01111101; // 12-bit result, FVR Buffer1, ADC enabled.
    ADCON1 = 0b11110011; // 2's format, FRC int. Clk, VREF = VDD, VREF- to GND.
    ADCON2 = 0b00001111; // Negative VRef sel. by ADRREF.

    WPUA = 0X00;

    INTCON_GIE; // GIE global interrupt enabled.

    PW_LED = true;
}