Hello! I'm wondering why my dissolved oxygen sensor is giving rather questionable readings. aside from licking the tip of the sensor I did everything correct from calibrating it correctly. also I set an led to whenever the dissolved oxygen levels go low it blinks. nut it does not. is this normal?
const int sensorPin = A0; // DO sensor analog signal
const int ledPin = 9; // LED pin
float voltage = 0.0;
float doLevel = 0.0;
void setup() {
pinMode(ledPin, OUTPUT);
Serial.begin(9600);
}
void loop() {
// Read raw value from sensor
int sensorValue = analogRead(sensorPin); // 0–1023
voltage = sensorValue * (3.3 / 1023.0); // Convert to voltage (0–3.3V)
// Convert to DO (mg/L), assuming 0–3.0V = 0–20 mg/L range
doLevel = (voltage / 5.0) * 20.0;
// Print debug info
Serial.print("Voltage: ");
Serial.print(voltage, 2);
Serial.print(" V | DO: ");
Serial.print(doLevel, 2);
Serial.println(" mg/L");
// If DO < 4 mg/L → blink LED
if (doLevel < 4.0) {
digitalWrite(ledPin, HIGH);
delay(300);
digitalWrite(ledPin, LOW);
delay(300);
} else {
digitalWrite(ledPin, LOW);
}
delay(200);
}