request: calibration example

[askmurphy]

Can you add a calibration example for calibration with pH buffers 4, 7 and 10?
Would be nice ;-)

[nthnn]

Hi! I don't think I quite get what that means. Can you elaborate what do you mean by "pH buffers"?

[askmurphy]

A pH sensor must be calibrated with special fluid called 'pH buffer'.
There are 3 buffers needed: pH4 , pH7 and pH10.

See this code for an example, maybe you can implement it:

void calibratePH() {
// pH 4.0 kalibratie
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Calibrating pH 4.0");
lcd.setCursor(0, 1);
lcd.print("Insert pH 4.0 buffer");
waitForButtonPress();
pH_4 = ph4502.read_ph_level();
lcd.clear();
lcd.print("pH 4.0 value:");
lcd.setCursor(0, 1);
lcd.print(pH_4, 2);
delay(2000);

// pH 7.0 kalibratie
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Calibrating pH 7.0");
lcd.setCursor(0, 1);
lcd.print("Insert pH 7.0 buffer");
waitForButtonPress();
pH_7 = ph4502.read_ph_level();
lcd.clear();
lcd.print("pH 7.0 value:");
lcd.setCursor(0, 1);
lcd.print(pH_7, 2);
delay(2000);

// pH 10.0 kalibratie
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Calibrating pH 10.0");
lcd.setCursor(0, 1);
lcd.print("Insert pH 10.0 buffer");
waitForButtonPress();
pH_10 = ph4502.read_ph_level();
lcd.clear();
lcd.print("pH 10.0 value:");
lcd.setCursor(0, 1);
lcd.print(pH_10, 2);
delay(2000);

// Kalibratiewaarden opslaan in EEPROM
saveCalibrationToEEPROM();

lcd.clear();
lcd.setCursor(0, 0);
lcd.print("Calibration complete");
delay(2000);

}

void loadCalibrationFromEEPROM() {
EEPROM.get(EEPROM_ADDRESS_PH_4, pH_4);
EEPROM.get(EEPROM_ADDRESS_PH_7, pH_7);
EEPROM.get(EEPROM_ADDRESS_PH_10, pH_10);
}

float readCalibratedPH() {
float pHValue = ph4502.read_ph_level();

// Perform calibration using stored values
if (pHValue < pH_7) {
    // Acidic range
    return 7 - (7 - PH_BUFFER_4) * (pH_7 - pHValue) / (pH_7 - pH_4);
} else {
    // Alkaline range
    return 7 + (PH_BUFFER_10 - 7) * (pHValue - pH_7) / (pH_10 - pH_7);
}

}

void loop() {
// Read pH level using calibration
float pHValue = readCalibratedPH();

// Display pH value on LCD
lcd.setCursor(0, 0);
lcd.print("pH: ");
lcd.print(pHValue, 2);

// Print pH value to serial monitor
Serial.print("pH: ");
Serial.println(pHValue, 2);

delay(1000);

}

More info: https://cwc.com.au/news-events/which-ph-buffer-solution-should-i-use-first-when-calibrating/

[nthnn]

It's quite comprehensive now. I get it that you want a functionality within the library to read a pH-calibrated values (for 4, 7, and 10), however, I may not be able to make experiments to further improve this library since I don't have any available PH4502C sensor (Just borrowed one from my school while developing this library).