Analog TDS sensor & PH sensor V2

Hello,

I have these two sensors installed to my arduino mega, but PH goes crazy after i measure the TDS sensor

I use 4 transistors to isolate positive and ground wires from the TDS sensor when im using the PH and the other way as well. Problem is, after i read the TDS it seems something happens in the water and the PH probe gets crazy..... the analog reading from the PH probe should be arround 250-350 and it goes to 50-90.

I tried everything, don't know what more i can do.... have you used TDS and PH probes at the same time?



 

Code: Select all#include <LiquidCrystal.h> #include <OneWire.h> #include <DallasTemperature.h> #include <EEPROM.h> ///////////TDS////////// #define TdsSensorPin A14 #define VREF 5.0      // analog reference voltage(Volt) of the ADC #define SCOUNT  5           // sum of sample point int analogBuffer[SCOUNT];    // store the analog value in the array, read from ADC int analogBufferTemp[SCOUNT]; int analogBufferIndex = 0, copyIndex = 0; float averageVoltage = 0, tdsValue = 0; //////////PH//////////// #define SensorPin A13            //pH meter Analog output to Arduino Analog Input 0 #define TDSoffset 0 #define Offset 3            //deviation compensate #define samplingInterval 20 #define printInterval 800 #define ArrayLenth  40    //times of collection #define ph2 6.3 #define ph1 7.5 #define v2 1.46 #define v1 1.60 int pHArray[ArrayLenth];   //Store the average value of the sensor feedback int pHArrayIndex = 0; bool AutoPH = false; int j = 0; int analogBuffer2[SCOUNT];    // store the analog value in the array, read from ADC int analogBufferTemp2[SCOUNT]; int analogBufferIndex2 = 0, copyIndex2 = 0; float averageVoltage2 = 0; /////////TDS&PH ON OFF///////// #define measureInterval 30000 #define TDSPin 51           //TDS meter for on/off #define PhPin 49            //pH meter for on/off ///////////Temperatura  ////////// OneWire ourWire1(42);  // Sensor temperatura DallasTemperature sensors1(&ourWire1); //Se declara una variable u objeto para nuestro sensor1 /////////LCD////////////////// // select the pins used on the LCD panel LiquidCrystal lcd(8, 9, 4, 5, 6, 7); // define some values used by the panel and buttons int lcd_key     = 0; int adc_key_in  = 0; #define btnRIGHT  0 #define btnUP     1 #define btnDOWN   2 #define btnLEFT   3 #define btnSELECT 4 #define btnNONE   5 // read the buttons int read_LCD_buttons() {  adc_key_in = analogRead(0);      // read the value from the sensor  // my buttons when read are centered at these valies: 0, 144, 329, 504, 741  // we add approx 50 to those values and check to see if we are close  if (adc_key_in > 1000) return btnNONE; // We make this the 1st option for speed reasons since it will be the most likely result  // For V1.1 us this threshold  if (adc_key_in < 50)   return btnRIGHT;  if (adc_key_in < 250)  return btnUP;  if (adc_key_in < 450)  return btnDOWN;  if (adc_key_in < 650)  return btnLEFT;  if (adc_key_in < 850)  return btnSELECT;  return btnNONE;  // when all others fail, return this... } void setup(void) {  sensors1.begin(); // Temperatura  pinMode(TdsSensorPin, INPUT);  pinMode(PhPin, OUTPUT); //PH off and on  pinMode(TDSPin, OUTPUT); //TDS off and on  digitalWrite(PhPin, 1);  digitalWrite(TDSPin, 0);  Serial.begin(9600);  Serial.println("pH meter experiment!");    //Test the serial monitor  lcd.begin(16, 2);              // start the library } void loop(void) {  static unsigned long samplingTime, samplingTime2, measureTime  = millis();  static unsigned long printTime = millis();  static float pHValue, voltage, TDSValue, voltage2;  sensors1.requestTemperatures();   //Se envía el comando para leer la temperatura  float temp1 = sensors1.getTempCByIndex(0); //Se obtiene la temperatura en ºC del sensor 1        if(millis()- measureTime > measureInterval )    {        if(j == 0)        {          j = 1;          digitalWrite(TDSPin,0);          delay(1000);          digitalWrite(PhPin,1);          delay(5000);          measureTime=millis();        }    }     if(millis()- measureTime > measureInterval)        {         if(j == 1)         {          j = 0;          digitalWrite(PhPin,0);          delay(1000);          digitalWrite(TDSPin,1);          measureTime=millis();        }          }      if(millis()-samplingTime > samplingInterval && digitalRead(PhPin) == 1)    {        pHArray[pHArrayIndex++]=analogRead(SensorPin);        if(pHArrayIndex==ArrayLenth)pHArrayIndex=0;        voltage = avergearray(pHArray, ArrayLenth)*5.0/1024;        pHValue = (ph2-ph1)/(v2-v1)*(voltage-v2)+ph2;        samplingTime=millis();      }   static unsigned long analogSampleTimepoint = millis();  if (millis() - analogSampleTimepoint > 5000 && digitalRead(TDSPin) == 1 )  //every 40 milliseconds,read the analog value from the ADC  {    analogSampleTimepoint = millis();    analogBuffer[analogBufferIndex] = analogRead(TdsSensorPin);    //read the analog value and store into the buffer    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; // read the analog value more stable by the median filtering algorithm, and convert to voltage value    float compensationCoefficient = 1.0 + 0.02 * (temp1 - 25.0); //temperature compensation formula: fFinalResult(25^C) = fFinalResult(current)/(1.0+0.02*(fTP-25.0));    float compensationVolatge = averageVoltage / compensationCoefficient; //temperature compensation    tdsValue = (133.42 * compensationVolatge * compensationVolatge * compensationVolatge - 255.86 * compensationVolatge * compensationVolatge + 857.39 * compensationVolatge) * 0.5; //convert voltage value to tds value    Serial.print("voltage:");    Serial.print(compensationVolatge, 2);    Serial.print(" TDS Value:");    Serial.print(tdsValue, 0);    Serial.print("ppm ");  }  if (millis() - printTime > printInterval)  //Every 800 milliseconds, print a numerical, convert the state of the LED indicator  {    Serial.print("VPH   ");    Serial.print(voltage, 4);        Serial.print(" Analogico   ");    Serial.print(analogRead(A13));    Serial.print(" PH Value:");    Serial.println(pHValue, 0);    lcd.setCursor(10, 0);    lcd.print("T:"); // print a simple message    lcd.setCursor(12, 0);           // move to the begining of the second line    lcd.print(analogRead(A13));  // read the buttons    lcd.setCursor(0, 0);    lcd.print("PH:"); // print a simple message    lcd.setCursor(3, 0);           // move to the begining of the second line    lcd.print(pHValue);  // read the buttons    lcd.setCursor(0, 1);    lcd.print("TDS:"); // print a simple message    lcd.setCursor(4, 1);           // move to the begining of the second line    lcd.print(tdsValue);  // read the buttons    printTime = millis();  }  // lcd.setCursor(0,1);            // move to the begining of the second line  // if(AutoPH=false)lcd.print("OFF");  // if(AutoPH=true)lcd.print("ON");  lcd_key = read_LCD_buttons();  // read the buttons  switch (lcd_key)               // depending on which button was pushed, we perform an action  {    case btnRIGHT:      {        break;      }    case btnLEFT:      {        break;      }    case btnUP:      {        break;      }    case btnDOWN:      {        break;      }    case btnSELECT:      {        AutoPH = !AutoPH;        break;      }    case btnNONE:      {        break;      }  } } double avergearray(int* arr, int number) {  int i;  int max, min;  double avg;  long amount = 0;  if (number <= 0) {    Serial.println("Error number for the array to avraging!/n");    return 0;  }  if (number < 5) { //less than 5, calculated directly statistics    for (i = 0; i < number; i++) {      amount += arr[i];    }    avg = amount / number;    return avg;  } else {    if (arr[0] < arr[1]) {      min = arr[0]; max = arr[1];    }    else {      min = arr[1]; max = arr[0];    }    for (i = 2; i < number; i++) {      if (arr[i] < min) {        amount += min;      //arr<min        min = arr[i];      } else {        if (arr[i] > max) {          amount += max;  //arr>max          max = arr[i];        } else {          amount += arr[i]; //min<=arr<=max        }      }//if    }//for    avg = (double)amount / (number - 2);  }//if  return avg; } 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; }