PIC16 ADC和输入阻抗

我有一些问题，ADC收购。我注意到ADC值具有“阶跃”特性。我的软件是：电压桥：649欧姆到3.6V，连接到CTN500欧姆到GND，一个100pF的电容器，用来过滤输入。我的配置：ADC开关50us的延迟和在ADCON1寄存器MEASURE_TEMPERATURE(){PIN_MEASUSUSU()中获取Fosc/32的数据。RE_TERATURE=1；//为温度测量ADRESH=0；//Init ADRESH ADRESL=0；//Init ADRESL ADC=0；//Init ADC变量ADC_Initialize()；//配置ADC通道并接受中断ADCON0bits.ADON=1；//将adc连接到VSS_._us(50)；ADCON0bits.GO_nDONE=1；//Start conv通过设置GOandDone变量.(ADCON0bits.GO_nDONE){}//等待转换结束ADC=(ADRESH<2)+(ADRESL>6)；/(ADRESH<8)+ADRESL;PIN_MEASURE_TEMPERATURE=0；//关闭用于温度测量的MOS FRAME_ADAPTA.()；//转换温度ADC值到帧温度格式}void ADC_Initialize(void){ADCON0=0b00010100；//RC1=AN5 ADCON1=0b00100000；//ADFM.；ADPREF VDD；ADCS FOSC/32；ADCON2=0b00000000；//TRIGSEL no_auto_.；ADRESL=0x00；//ADRESL 0x0；//ADRESH 0x0；}



      以下为原文

    I have some problems with ADC acquisition. I notice that the ADC value has a "step" behaviour.
My harware: Voltage bridge: 649Ohms to 3.6V connected to CTN500Ohms to GND, a capacitor of 100pF to filter the input.
My configuration:
Delay of 50us betwen ADC switch ON and data acquire
Fosc/32 in the ADCON1 register

MEASURE_TEMPERATURE()
{
PIN_MEASURE_TEMPERATURE=1; //Put the MOS ON for the temperature measure
ADRESH=0; //Init ADRESH
ADRESL=0; //Init ADRESL
ADC =0; //Init ADC variable
ADC_Initialize(); //Configure ADC Channel and accept interrupt
ADCON0bits.ADON = 1; //Connect adc to VSS
__delay_us(50);
ADCON0bits.GO_nDONE = 1; // Start conversion by setting the GOandDone variable
while (ADCON0bits.GO_nDONE){} // Wait end of conversion
ADC = (ADRESH << 2) + (ADRESL >> 6); //(ADRESH << 8) + ADRESL;
PIN_MEASURE_TEMPERATURE=0; //Switch off the MOS used for temperature measurement
FRAME_ADAPTATION(); //Conversion of the temperature ADC value to frame temperature format
}

void ADC_Initialize(void)
{
ADCON0 = 0b00010100; // RC1=AN5
ADCON1 = 0b00100000; // ADFM left; ADPREF VDD; ADCS FOSC/32;
ADCON2 = 0b00000000; // TRIGSEL no_auto_trigger;
ADRESL = 0x00; // ADRESL 0x0;
ADRESH = 0x00; // ADRESH 0x0;
}