Flowmeter with no interrupts 32U4

Other Hardware Sensors
1

Hi guys!

I have a question and I need some help, I triend many times but obtained zero results.

I want to measure two waterflows through two pipes with two flowmeters connected to an Arduino Pro Micro, those one with a spinning wheel, that means, the flow is linear related with the frequency. I have the formula, but not the way to measure the frequency.

The problem is I CAN NOT USE INTERRUPTS, I am hardware forced to use pin D6 and D7. D7 has INT but D6 has no INT nor PCINT.

So, how can I proceed to measure the flow without blocking to much the other sensors reading (temperature, pressure etc) and I2C JSON sending to a connected RaspberryPi?

Thanks in advance, everything works, but I didn´t find the way to implement this...

Greetings!

Raphael M. Trautmann

2

Can you use pin change interrupts (there's a library) on the Pro Micro?

3

I guess, but pin D6 does not work with PCINT...

4

Just poll the pins. No need for interrupts with a flowmeter.

Of course, you will not be able to use delay() in the polling loop, or you will miss pulses.

pin D6 does not work with PCINT

What makes you believe this?

5

No INT or PCINT on pin 6 here: https://www.arduino.cc/en/Hacking/PinMapping32u4.
Pin 6 is not in the list here: Usage · GreyGnome/EnableInterrupt Wiki · GitHub.

@RTDesigns, why are you forced to use pin 6 ?
Can you cheat a little by connecting another pin to pin 6 ?
The solution by jremington (just poll the pins) should work. What is the maximum frequency and the minimal pulse duration of the flow meter ? Can you show the sketch ?

6

I would just do as post #3 suggest. Your flow sensor outputs a number of pulses per unit of flow. So measure the High time and Low time on a pin. High time + Low time is the period and 1/Period is the frequency. Now depending on the sensor K factor (pulses per unit of measure) you derive the flow rate. You do not need an interrupt to measure flow.

Ron

7

jremington:
Just poll the pins. No need for interrupts with a flowmeter.

Of course, you will not be able to use delay() in the polling loop, or you will miss pulses.
What makes you believe this?

Yeah I know, I should do it with millis(). Okay thanks a lot!! I wil try!!!! :slight_smile:

8

Koepel:
No INT or PCINT on pin 6 here: https://www.arduino.cc/en/Hacking/PinMapping32u4.
Pin 6 is not in the list here: Usage · GreyGnome/EnableInterrupt Wiki · GitHub.

@RTDesigns, why are you forced to use pin 6 ?
Can you cheat a little by connecting another pin to pin 6 ?
The solution by jremington (just poll the pins) should work. What is the maximum frequency and the minimal pulse duration of the flow meter ? Can you show the sketch ?

I am forced to use this pins because I designed and ordered a PCB, with this asignations.
For now I didn´t calculate frequency or pulse duration, but I guess not very high frequency, because its a flowmeter in a piping with a lower flowrate than the water coming from a water tap.
I didn´t have anything done with this in the sketch, just this:

/**

  • Caudales: 2 sensores, caudalímetro
    */
    // Pines asociados
    const static byte FLOW1_PIN = 6;
    const static byte FLOW2_PIN = 7;
    // Número de sensores
    const static byte FLOW_NMETERS = 2;
    // Valor de las medidas
    float flowMeasures[FLOW_NMETERS];
    // Para debug

void printFlows();

I can´t cheat pins because everyone is assigned, I have about 9 temperature sensors, 4 pressure sensors, etc...

I will try like you guys told me, polling!! Thanks!

9

Ron_Blain:
I would just do as post #3 suggest. Your flow sensor outputs a number of pulses per unit of flow. So measure the High time and Low time on a pin. High time + Low time is the period and 1/Period is the frequency. Now depending on the sensor K factor (pulses per unit of measure) you derive the flow rate. You do not need an interrupt to measure flow.

Ron

Thanks!! I will try this yeah!

10

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