pH Sensor - how to code reading?

Other Hardware Sensors
1

So I've build a pH amplifier circuit which gives a reading of 0V to 3.148V (0 - 14 pH) in 0.02pH per step.

How do I now interface this to the Arduino. I know I need to use the AnalogueRead function but how do I cater for the value being from 0 to 3.148V ( and not 0-5V)
At 1.574V it should display a pH of 7.

2

To get better resolution you can connect the 3.3V pin to the Aref pin and in setup() write:

analogReference(EXTERNAL);

Then the 0-1024 input range maps to 0-3.3V:

float voltage = (analogRead(pin) * 3.3) / 1024.0;

3

Thanks - I"ll try that. I found a few references and came up with this:

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}


void loop() {
  // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // Convert the analog reading (which goes from 0 - 1023) to a voltage (0 - 5V):
  float voltage = sensorValue * (5.0 / 1023.0);

  Serial.print("pH:");
  
  float ph = voltage * (14.000 / 3.148);
  Serial.println(ph);
  
  delay(1000);
}