// These values help bring the readings from the water in evenely and throw out errant readings. int meter1[10]; int meter2[10]; byte sampleCount = 0; byte currSample = 0; byte readingLow = 0; // The reading on the LOWER sensor byte readingHigh = 0; // The reading on the HIGHER sensor byte blinkPattern = 0; // Number of blinks. byte blinkPoint = 0; // The pins where items are connected #define PIN_SENSE_LOW 5 // The LOW sense wire (bottom of dish) #define PIN_SENSE_HIGH 9 // The HIGH sense wire (top of dish) #define PIN_WATER 12 // Turn on the water flow #define PIN_BUZZER 6 // Piezo buzzer for alerts #define PIN_SENSE_POWER 8 // Turn on the power for the sensors to prevent corrosion void setup() { // Pin 13 has an LED connected on most Arduino boards: pinMode(13, OUTPUT); pinMode(PIN_SENSE_LOW, INPUT); pinMode(PIN_SENSE_HIGH, INPUT); pinMode(PIN_WATER, OUTPUT); pinMode(PIN_BUZZER, OUTPUT); pinMode(PIN_SENSE_POWER, OUTPUT); // Make sure these things are off. digitalWrite(PIN_WATER, LOW); digitalWrite(PIN_SENSE_POWER, LOW); // Startup sound buzz(230); buzz(270); buzz(320); // Open the serial connection for debugging Serial.begin(9600); } void loop() { long timerA = 0; long timerB = 0; // Main logic loop. if (sampleCount < 10) // Not enough readings yet. 10 readings are needed as a baseline. { updateSensors(); } else { // LOGIC LOOP A blinkPattern = 60; Serial.println("A. Waiting for No Low"); waitForNoLow(); // At this point, the LOW sensor is not activated. // Try for another 30 seconds to see if it will come back. blinkPattern = 10; Serial.println("B. No Low Detected. Confirming for 30 seconds."); timerA = millis(); do { delay(500); updateSensors(); if (millis() - timerA > 30000 || millis() < timerA) break; } while (readingLow == 0 && readingHigh == 0); // Are we still reading no low? if (readingLow == 0) { // Now we wait 30 minutes to let the water evaporate. // 10 minutes = 1800 seconds. blinkPattern = 2; // Alert that we have entered this state via buzzer. buzz(230); delay(200); buzz(230); Serial.println("C. No Low confirmed. Evaporating for 10 minutes."); for (int i = 0; i < 1800; i++) { doBlinks(); delay(1000); } // Turn on the water. blinkPattern = 3; Serial.println("WATER: TURNING ON"); buzz(270); buzz(230); digitalWrite(PIN_WATER, HIGH); // Start timer B. timerB = millis(); // Monitor the water levels. Serial.println("D. Monitoring water levels..."); do { delay(20); updateSensors(); if (millis() - timerB > 35000 || millis() < timerB) { Serial.println("Water should be full by now. Detection failure."); // Enter the error state. digitalWrite(PIN_WATER, LOW); do { alarm(5); } while (true); // Infinite loop, requires user reset. break; } } while (readingHigh == 0); Serial.println("E. Fill level reached."); Serial.println("WATER: TURNING OFF"); digitalWrite(PIN_WATER, LOW); buzz(230); buzz(270); // At this point the loop begins again. } else { Serial.println("False positive. The low water is back."); } } delay(20); } // This function waits for the dish to be empty. void waitForNoLow() { do { delay(10000); // Check once every 10 seconds. updateSensors(); } while (readingLow == 1 || readingHigh == 1); } void doBlinks() { if (blinkPoint == 0) { digitalWrite(13, HIGH); delay(10); digitalWrite(13, LOW); } blinkPoint++; if (blinkPoint > blinkPattern) blinkPoint = 0; } void buzz(long nFreq) { for (long i = 0; i < 1000; i++ ) { // 1 / 2048Hz = 488uS, or 244uS high and 244uS low to create 50% duty cycle digitalWrite(PIN_BUZZER, HIGH); delayMicroseconds(nFreq); digitalWrite(PIN_BUZZER, LOW); delayMicroseconds(nFreq); } } void alarm(byte nCount) { for (byte i = 0; i < nCount; i++) { buzz(230); buzz(270); } } void updateSensors() { // Take a sample digitalWrite(PIN_SENSE_POWER, HIGH); delay(1); byte m1 = digitalRead(PIN_SENSE_LOW); byte m2 = digitalRead(PIN_SENSE_HIGH); // Turn this off to not cause corrosion digitalWrite(PIN_SENSE_POWER, LOW); meter1[currSample] = m1; meter2[currSample] = m2; currSample++; if (currSample > 9) currSample = 0; if (sampleCount < 10) { // First 10 samples are not counted sampleCount++; } else { // All samples have to be the same to change the reading. float t1 = 0; float t2 = 0; for (byte i = 0; i < 10; i++) { t1 = t1 + meter1[i]; t2 = t2 + meter2[i]; } t1 = t1 / 10; t2 = t2 / 10; if (t1 == 0 || t1 == 1) { // All samples are the same readingLow = t1; } if (t2 == 0 || t2 == 1) { // All samples are the same readingHigh = t2; } } doBlinks(); }