Using two flow sensors connected to one Arduino.

Other Hardware Sensors
15

Thanks. I have cleaned up a bit more here, but its not perfect yet. The whole system is not accurate enough. I need the sensors to be very accurate for this project, and I think it is something inside here who makes the difference:

#define IRQ_A 0
#define IRQ_B 1
#define FlowA 2
#define FlowB 3

volatile unsigned long countIN = 0;
volatile unsigned long countOUT = 0;
unsigned long oldTime  = 0;
float flowRate;



volatile float pulseCountIN;
volatile float pulseCountOUT;
volatile float pulseCount;

float liters;

void setup()
{
  Serial.begin(57600);
  
  pulseCountIN = 0.0;
  pulseCountOUT = 0.0;
  pulseCount = 0.0;
  flowRate = 0.0;

  pinMode(FlowA, INPUT);
  pinMode(FlowB, INPUT);
  digitalWrite(FlowA, HIGH);
  digitalWrite(FlowB, HIGH);
  
  liters = 0.0;

  attachInterrupt(IRQ_A, CounterIN, FALLING);
  attachInterrupt(IRQ_B, CounterOUT, FALLING);
}

void loop()
{
  unsigned long now = millis();
  if(now - oldTime >= 1000)
  {
    unsigned long duration = now - oldTime;
    oldTime = now;

    liters = (countIN - countOUT); 
    float litersPerMinute = (1000 * liters)/duration;    
    int LPM = litersPerMinute;           
    
    pulseCount = (pulseCountIN - pulseCountOUT) / 10000.0 * 3600;
       

    flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount);
    unsigned int frac;
    Serial.print("Liter per time: ");
    Serial.println(pulseCount, 4);
      
    pulseCountIN = 0;
    pulseCountOUT = 0;
     
  }
}

void CounterIN()
{
  countIN++;
  pulseCountIN++;
}

void CounterOUT()
{
  countOUT++;
  pulseCountOUT++;
}

When I connect the hoses and sensors to the water faucet, the sensors gives me this: results
Liter per time: 23.4000
Liter per time: 24.1200
Liter per time: 24.8400
Liter per time: 25.2000
Liter per time: 25.5600
Liter per time: 24.8400

...and that is not what I had expected.
The engines I develop this flow meter to, uses between 3 and 50 liters per hour.

Do you understand what I have done wrong?

Cheers, Fredrik