TDS METER CẢM BIẾN HÀM LƯỢNG CHẤT RẮN HÒA TAN

#define TdsSensorPin A1

#define VREF 5.0      

#define SCOUNT  30          

int analogBuffer[SCOUNT];  

int analogBufferTemp[SCOUNT];

int analogBufferIndex = 0,copyIndex = 0;

float averageVoltage = 0,tdsValue = 0,temperature = 25;

void setup()

{

    Serial.begin(115200);

    pinMode(TdsSensorPin,INPUT);

}

void loop()

{

   static unsigned long analogSampleTimepoint = millis();

   if(millis()-analogSampleTimepoint > 40U)    

   {

     analogSampleTimepoint = millis();

     analogBuffer[analogBufferIndex] = analogRead(TdsSensorPin);  

     analogBufferIndex++;

     if(analogBufferIndex == SCOUNT)

         analogBufferIndex = 0;

   }  

   static unsigned long printTimepoint = millis();

   if(millis()-printTimepoint > 800U)

   {

      printTimepoint = millis();

      for(copyIndex=0;copyIndex<SCOUNT;copyIndex++)

        analogBufferTemp[copyIndex]= analogBuffer[copyIndex];

      averageVoltage = getMedianNum(analogBufferTemp,SCOUNT) * (float)VREF / 1024.0;

      float compensationCoefficient=1.0+0.02*(temperature-25.0);  

      float compensationVolatge=averageVoltage/compensationCoefficient;  

      tdsValue=(133.42*compensationVolatge*compensationVolatge*compensationVolatge - 255.86*compensationVolatge*compensationVolatge + 857.39*compensationVolatge)*0.5;

      Serial.print("TDS Value:");

      Serial.print(tdsValue,0);

      Serial.println("ppm");

   }

}

int getMedianNum(int bArray[], int iFilterLen)

{

      int bTab[iFilterLen];

      for (byte i = 0; i<iFilterLen; i++)

      bTab[i] = bArray[i];

      int i, j, bTemp;

      for (j = 0; j < iFilterLen - 1; j++)

      {

      for (i = 0; i < iFilterLen - j - 1; i++)

          {

        if (bTab[i] > bTab[i + 1])

            {

        bTemp = bTab[i];

            bTab[i] = bTab[i + 1];

        bTab[i + 1] = bTemp;

         }

      }

      }

      if ((iFilterLen & 1) > 0)

    bTemp = bTab[(iFilterLen - 1) / 2];

      else

    bTemp = (bTab[iFilterLen / 2] + bTab[iFilterLen / 2 - 1]) / 2;

      return bTemp;

}