/* Liquid flow rate sensor -DIYhacking.com Arvind Sanjeev Measure the liquid/water flow rate using this code. Connect Vcc and Gnd of sensor to arduino, and the signal line to arduino digital pin 2. Only modification by Gautam - Calibration changed to 7.5 on line 19 from 4.5 */ byte statusLed = 13; byte sensorInterrupt = 1; // 0 = digital pin 2 byte sensorPin = 3; // The hall-effect flow sensor outputs approximately 4.5 pulses per second per // litre/minute of flow. float calibrationFactor = 7.5; volatile byte pulseCount; float flowRate; unsigned int flowMilliLitres; unsigned long totalMilliLitres; unsigned long oldTime; void setup() { // Initialize a serial connection for reporting values to the host Serial.begin(9600); // Set up the status LED line as an output pinMode(statusLed, OUTPUT); digitalWrite(statusLed, HIGH); // We have an active-low LED attached pinMode(sensorPin, INPUT); digitalWrite(sensorPin, HIGH); pulseCount = 0; flowRate = 0.0; flowMilliLitres = 0; totalMilliLitres = 0; oldTime = 0; // The Hall-effect sensor is connected to pin 2 which uses interrupt 0. // Configured to trigger on a FALLING state change (transition from HIGH // state to LOW state) attachInterrupt(sensorInterrupt, pulseCounter, FALLING); } /** Main program loop */ void loop() { if ((millis() - oldTime) > 1000) // Only process counters once per second { // Disable the interrupt while calculating flow rate and sending the value to // the host detachInterrupt(sensorInterrupt); // Because this loop may not complete in exactly 1 second intervals we calculate // the number of milliseconds that have passed since the last execution and use // that to scale the output. We also apply the calibrationFactor to scale the output // based on the number of pulses per second per units of measure (litres/minute in // this case) coming from the sensor. flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor; // Note the time this processing pass was executed. Note that because we've // disabled interrupts the millis() function won't actually be incrementing right // at this point, but it will still return the value it was set to just before // interrupts went away. oldTime = millis(); // Divide the flow rate in litres/minute by 60 to determine how many litres have // passed through the sensor in this 1 second interval, then multiply by 1000 to // convert to millilitres. flowMilliLitres = (flowRate / 60) * 1000; // Add the millilitres passed in this second to the cumulative total totalMilliLitres += flowMilliLitres; unsigned int frac; // Print the flow rate for this second in litres / minute Serial.print("Flow rate: "); Serial.print(int(flowRate)); // Print the integer part of the variable Serial.print("."); // Print the decimal point // Determine the fractional part. The 10 multiplier gives us 1 decimal place. frac = (flowRate - int(flowRate)) * 10; Serial.print(frac, DEC) ; // Print the fractional part of the variable Serial.print("L/min"); // Print the number of litres flowed in this second Serial.print(" Current Liquid Flowing: "); // Output separator Serial.print(flowMilliLitres); Serial.print("mL/Sec"); // Print the cumulative total of litres flowed since starting Serial.print(" Output Liquid Quantity: "); // Output separator Serial.print(totalMilliLitres); Serial.println("mL"); // Reset the pulse counter so we can start incrementing again pulseCount = 0; // Enable the interrupt again now that we've finished sending output attachInterrupt(sensorInterrupt, pulseCounter, FALLING); } } /* Insterrupt Service Routine */ void pulseCounter() { // Increment the pulse counter pulseCount++; }