003的ADC稳定吗？

只看该作者 · 2018-6-1 09:15

用003做了个温度采集的，用的是P0.4(AIN5)ADC丢弃了前2个包，取后3个,测VDD老是跳。
已配置模拟输入了。
代码如下：
void main (void)
{
    //unsigned char i;
double bgvalue;
double digitalValue,voltageValue,Rt;
unsigned int i;
double temp;
char xdata info[50],info2[50];

Set_All_GPIO_Quasi_Mode; // Define in Function_define.h

InitialUART0_Timer1(115200);
OLED_Init(); //OLED初始化
READ_BANDGAP();

Enable_ADC_BandGap;

CKDIV = 0x02; // IMPORTANT!! Modify system clock to 4MHz ,then add the ADC sampling clock base to add the sampling timing.
for(i=0;i<5;i++) // All following ADC detect timing is 200uS run under 4MHz.
{
clr_ADCF;
set_ADCS;
   while(ADCF == 0);
ADCdataH[i] = ADCRH;
ADCdataL[i] = ADCRL;
}
CKDIV = 0x00; // After ADC sampling, modify system clock back to 16MHz to run next code.

clr_ADCEN;

for(i=2;i<5;i++) // use the last 3 times data to make average
{
ADCsumH = ADCsumH + ADCdataH[i];
ADCsumL = ADCsumL + ADCdataL[i];
}
ADCavgH = ADCsumH/3;
ADCavgL = ADCsumL/3;
bgvalue = (ADCavgH<<4) + ADCavgL;
VDD_Voltage = (0x1000/bgvalue)*Bandgap_Voltage/1000;
printf ("\n BG ROMMAP = %f",Bandgap_Voltage);
printf ("\n VDD voltage = %f", VDD_Voltage);

P04_Input_Mode;
Enable_ADC_AIN5;  // Enable AIN0 P0.4 as ADC input, Find in "Function_define.h" - "ADC INIT"

while(1){

   CKDIV = 0x02; // IMPORTANT!! Modify system clock to 4MHz ,then add the ADC sampling clock base to add the sampling timing.
for(i=0;i<5;i++) // All following ADC detect timing is 200uS run under 4MHz.
{
clr_ADCF;
set_ADCS;
   while(ADCF == 0);
ADCdataH[i] = ADCRH;
ADCdataL[i] = ADCRL;
}
CKDIV = 0x00; // After ADC sampling, modify system clock back to 16MHz to run next code.

ADCsumH=0;
ADCsumL=0;
for(i=2;i<5;i++) // use the last 3 times data to make average
{
ADCsumH = ADCsumH + ADCdataH[i];
ADCsumL = ADCsumL + ADCdataL[i];
}

ADCavgH = ADCsumH/3;
ADCavgL = ADCsumL/3;
bgvalue = (ADCavgH<<4) + ADCavgL;
printf ("\nbgvalue = %f",bgvalue);
printf ("\n BG ROMMAP = %f",Bandgap_Voltage);
printf ("\n VDD voltage = %f", VDD_Voltage);
Res_Voltage=4095/bgvalue*Bandgap_Voltage/1000;

sprintf (&info,"Res_V= %f",Res_Voltage);

  //获得端口处的电压值
  digitalValue=bgvalue;
  voltageValue=(digitalValue/4095)*VDD_Voltage;
  printf("Current voltage value=%3f",voltageValue);

  voltagePower=VDD_Voltage;

  //通过分压比获得热敏电阻的阻值
  Rt=((voltagePower-voltageValue)*Rs)/voltageValue;
  printf("Current registor value=%3f",Rt);


  //换算得到温度值
  temp=(((T1*BZ)/(BZ+T1*log(Rt/R1)))-273.15);//
  printf("Current temperature value=%3f",temp);
  sprintf(&info2,"tempv=%3f",temp);

OLED_P8x16Str(0,0,&info);
OLED_P8x16Str(0,2,&info2);
//Res_Voltage*100000;
/*
for(i=0;i<105;i++) // use the last 3 times data to make average
{
if ((Temp_Voltage<dTemp[i])&&(Temp_Voltage>dTemp[i+1]))
      temp=i-20;
}

//printf ("\nRes_Voltage  = %10f",Res_Voltage);
   //printf ("\nTemp_Voltage = %3f",Temp_Voltage);
sprintf (&info,"Temp = %3f",temp);
*/
//OLED_P8x16Str(0,2,&info);
Timer3_Delay100ms(10);
//OLED_CLS();
}

温度采集每次都变动很大，小的时候0.05，大的时候0.5-0.6度。
同一个电阻和3435温度电阻在arduino 里很稳定。

1万 · 2018-6-1 09:26

测出来的结果跟温度计显示的差别大吗

1万 · 2018-6-1 09:26

如果有轻微的跳动，你可以使用滤波。

只看该作者 · 2018-6-1 09:52

N76E003的AD是12位的你可以采集16组数据然后从小到大排序去掉最大值最小值剩下的求平均；有好多种 AD采样数据滤波算法你可以百度下

只看该作者 · 2018-6-1 10:00

003的ADC本身稳定性没有问题，由于采用的是Vcc作为ADC基准，因此，关键就变成芯片供电的稳定了，对ADC稳定性有特别要求的，建议把单独的稳压器，就近给单片机直接供电，并在稳压器输出端并联足够的旁路电容。以满足Vcc稳定的基本要求。

只看该作者 · 2018-6-1 10:29

tianxj01 发表于 2018-6-1 10:00
003的ADC本身稳定性没有问题，由于采用的是Vcc作为ADC基准，因此，关键就变成芯片供电的稳定了，对ADC稳定 ...

有的芯片可以选择ADC以VDD为基准还是以带隙基准为参考，这样就方便多了，否则外围太复杂了。毕竟这是1块多的芯片啊

只看该作者 · 2018-6-1 12:16

改成中值滤波还是没用，看样子是硬件电路毛病了

READ_BANDGAP();

Enable_ADC_BandGap;

CKDIV = 0x02; // IMPORTANT!! Modify system clock to 4MHz ,then add the ADC sampling clock base to add the sampling timing.
for(i=0;i<Fn+3;i++) // All following ADC detect timing is 200uS run under 4MHz.
{
clr_ADCF;
set_ADCS;
   while(ADCF == 0);
   if (i>2)
   {
      ADCdataH[i-3] = ADCRH;
      ADCdataL[i-3] = ADCRL;
   }
}
CKDIV = 0x00; // After ADC sampling, modify system clock back to 16MHz to run next code.

clr_ADCEN;

ADCavgH = middleValueFilter(ADCdataH);
ADCavgL = middleValueFilter(ADCdataL);

bgvalue = (ADCavgH<<4) + ADCavgL;
VDD_Voltage = (0x1000/bgvalue)*Bandgap_Voltage/1000;
printf ("\n BG ROMMAP = %f",Bandgap_Voltage);
printf ("\n VDD voltage = %f", VDD_Voltage);

P04_Input_Mode;
Enable_ADC_AIN5;  // Enable AIN0 P0.4 as ADC input, Find in "Function_define.h" - "ADC INIT"

while(1){

   CKDIV = 0x02; // IMPORTANT!! Modify system clock to 4MHz ,then add the ADC sampling clock base to add the sampling timing.

for(i=0;i<Fn+3;i++) // All following ADC detect timing is 200uS run under 4MHz.
{
clr_ADCF;
set_ADCS;
   while(ADCF == 0);
   if (i>2)
   {
      ADCdataH[i-3] = ADCRH;
      ADCdataL[i-3] = ADCRL;
   }
}
CKDIV = 0x00; // After ADC sampling, modify system clock back to 16MHz to run next code.

clr_ADCEN;

ADCavgH = middleValueFilter(ADCdataH);
ADCavgL = middleValueFilter(ADCdataL);

bgvalue = (ADCavgH<<4) + ADCavgL;
printf ("\nbgvalue = %f",bgvalue);
printf ("\n BG ROMMAP = %f",Bandgap_Voltage);
printf ("\n VDD voltage = %f", VDD_Voltage);
Res_Voltage=4095/bgvalue*Bandgap_Voltage/1000;

sprintf (&info,"Res_V= %f",Res_Voltage);