💬 Water Meter Pulse Sensor

  • Admin

    This thread contains comments for the article "Water Meter Pulse Sensor" posted on MySensors.org.

  • I get error on compiling.
    "exit status 1
    call of overloaded 'set(volatile long unsigned int&)' is ambiguous"

    The following line gets red marked in Arduino IDE
    send(lastCounterMsg.set(pulseCount)); // Send pulsecount value to gw in VAR1

  • Admin

    Compiles fine here in 1.6.12..

  • Running 1.6.11, will try and update.

  • Should have said that I was trying to run it on a Node MCU 0.9. I can compile fine for Arduino Nano but not for Node MCU. Also I got another error now when I upgraded to 1.6.12.

    In file included from C:\Users\xxxxx\Documents\Arduino\libraries\MySensors-development/MySensors.h:337:0,
                     from C:\Users\xxxxxxx\AppData\Local\Temp\untitled921979828.tmp\sketch_oct14a\sketch_oct14a.ino:44:
    C:\Users\xxxxxxx\Documents\Arduino\libraries\MySensors-development/core/MyMainESP8266.cpp:4:22: fatal error: Schedule.h: No such file or directory
     #include "Schedule.h"
    compilation terminated.
    exit status 1
    Error compiling for board NodeMCU 0.9 (ESP-12 Module).```

  • Admin

    Please update NodeMCU in board manager to rc3.

    Hmm .. I can see the "overloaded 'set(volatile long unsigned int&)' is ambiguous" error here as well... I wonder why it behaves differently from Arduino...

  • Admin

    Works if you replace

    volatile unsigned long pulseCount = 0;


    volatile uint16_t pulseCount = 0;

  • Great! Thanks for the help 🙂
    Now I just need to figure out a good placement for it and get values to Domoticz.
    But this helped me a lot to get started.

  • It is not clear to me from the picture if the water meter pulse output leads go to gnd and VCC or VCC and DO? The water-meter pulse output is only two leads.

    I am going to MySensors with great hope on this water meter sensor. I have the Vera gateway working fine. Now the test with my first and most important sensor!

    Thanks in advance

  • Mod

    @vikram0228 I haven't built this node, but the pictures and the connections table on the page describes three leads. Do you have a different sensor?

  • Water Meters with pulse output have two leads. They generate a simple pulse.

    The MySensors circuit also should also work with two leads - just need to know which two. The three leads are for water meters with no pulse output and where you need an optical sensor to sense the moving wheel.

  • Hi.
    Cant get my watersensor to send any values.
    I have debug enabled and it seems like it communicates fine with the gw but no flow data are beeing reported to the gw or the serial monitor.
    TSP:MSG:SEND 4-4-0-0 s=1,c=2,t=24,pt=0,l=0,sg=0,ft=0,st=ok:
    Anyone else experienced this problem?

  • I wanted to operate my water pulse meter on batteries and also get the water flow. The original design had the following issues with that:

    • Incorrect flow calc: micros() was used to calculate the flow, however micros() wraps every 70 minutes which looks like a huge flow (which is then discarded in code)
    • Volume calc: millis() wraps every 50 days which is not handled correctly either
    • Too much current for battery use: The IR LED of the TCRT5000 is always on and the LM393 comparator is also taking a few mA's
    • Could not report flow in sleep mode because millis() does not increment on sleep - need to do this based on calculation of total sleep time. We now simply calculate the number of pulses per minute and deduct the flow
    • I also had issued with the data transport reliability, so I added error counters (which show up on the Gateway as distance sensors)
    • I also wanted to provide a measurement counter to the gateway (that counts up each time a message is sent)
    • The sensor will reboot itself when too many errors occur

    So I modified the circuit of the IR sensor:

    • Assumption that the wheel of the water meter turns slowly (takes at least a few seconds to turn around)
    • We will wake up every 500 millisecond to turn on the IR LED connected to PIN 8. Pin 8 also powers the photo transistor that measures the reflection
    • I removed the power from the opamp circuit that is linked to the photo transistor
    • The voltage from the photo transistor is then read using an analog read on A1. Based on a threshold value we will deduct if the mirror on the water meter is in view
    • Pin 7 is connected to a learning switch which will turn the device in a specific mode and the min/max values on A1 are used to calculate the value of the threshold (which is then stored in the EEPROM)
    • After 30 seconds in learning mode, the new threshold is established and the LED on Pin 6 will show the actual on/off mirror signals, so you can see the pulses are correctly counted
    • switch back the DIP switch on Pin 7 to bring back normal mode
    • The circuit also contains the battery voltage sensor circuit (I am using a 1.5V battery and step up circuit). So the resistors used are 470k from + pole of battery to the A0 input and 1 M ohm from A0 to ground
     * Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
     * Copyright (C) 2013-2015 Sensnology AB
     * Full contributor list: https://github.com/mysensors/Arduino/graphs/contributors
     * Documentation: http://www.mysensors.org
     * Support Forum: http://forum.mysensors.org
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * version 2 as published by the Free Software Foundation.
     * Version 1.0 - Henrik Ekblad
     * Version 1.1 - GizMoCuz
     * Version 1.2 - changed BM: using low power separate circuit for infra red on pin 8 + analog A1
     * Incorrect flow calc: micros() was used to calculate the flow, however micros() is wraps every 70 minutes which looks like a huge flow (which is discarded)
     * Volume calc: millis() wraps every 50 days which is not handled correctly
     * Too much current for battery use: The IR LED of the TCRT5000 is always on and the LM393 comparator is also taking a few mA's
     * Could not report flow in sleep mode because millis() does not increment on sleep - need to do this based on calculation of total sleep time
     * Assumption that the wheel of the water meter turns slowly (takes at least a few seconds to turn around)
     * We will wake up every second to turn on the IR LED (connected to PIN 8). Pin 8 also powers the photo transistor that measures the reflection
     * The voltage from the photo transistor is then read using an analog read on A1. Based on a treshold value we will deduct if the mirror is in view
     * Pin 7 is connected to a learning switch which will turn the device in continous mode and the min/max values on A1 are used to recalc the treshold
     * during a 30 second period. After this period the new treshold is established and the LED on Pin 6 will show the actual on/off mirror signals
     * http://www.mysensors.org/build/pulse_water
    // BOARD: PRO MINI 3.3V/ 8Mhz ATMEGA328 8Mhz
    // Enable debug prints to serial monitor
    #define MY_DEBUG 
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    #define MY_NODE_ID 10                 // hard code the node number
    #include <SPI.h>
    #include <MySensors.h>  
    #define SENSOR_POWER 8                // pin that will provide power to IR LED + sense circuit
    #define IR_SENSE_PIN  A1              // input for IR voltage
    #define BATTERY_SENSE_PIN  A0         // select the input pin for the battery sense point
    #define LEARN_SWITCH_PIN 7            // switch (SW1 on battery module) to turn on learning mode (low==on)
    #define LEARN_LED_PIN 6               // LED feedback during learning mode (LED on battery module)
    #define LEARN_TIME 30                 // number of seconds we will keep learn loop
    #define PULSE_FACTOR 1000             // Nummber of blinks per m3 of your meter (One rotation/1 liter)
    #define MAX_FLOW 80                   // Max flow (l/min) value to report. This filters outliers.
    #define CHILD_ID 1                    // Id of the sensor child (contains 3 subs: V_FLOW, V_VOLUME, VAR1)
    #define CHILD_PINGID 2                // ID of ping counter
    #define CHILD_ERRID 3                 // ID of error counter
    #define CHECK_FREQUENCY 500           // time in milliseconds between loop (where we check the sensor) - 500ms   
    #define MIN_SEND_FREQ 60              // Minimum time between send (in multiplies of CHECK_FREQUENCY). We don't want to spam the gateway (30 seconds)
    #define MAX_SEND_FREQ 1200            // Maximum time between send (in multiplies of CHECK_FREQUENCY). We need to show we are alive (600 sec/10 min)
    #define IR_ON_SETTLE 2                // number of milliseconds after we turned on the IR LED and we assume the receive signal is stable (in ms)
    #define EE_TRESHOLD 10                // config addresses 0 + 1 used for treshold from learning (loadState() returns only uint8 value)
    #define TRESHOLD_MARGIN 3             // additional margin before we actually see a one or zero
    #define RESETMIN 5                    // number of cycle times (either 30 sec of 10 min) we consistently need to have transmission errors before we perform hard reset
    MyMessage volumeMsg(CHILD_ID,V_VOLUME); // display volume and flow on the same CHILD_ID
    MyMessage flowMsg(CHILD_ID,V_FLOW); // flow
    MyMessage lastCounterMsg(CHILD_ID,V_VAR1);
    MyMessage pingMsg(CHILD_PINGID,V_DISTANCE); // use distance to keep track of changing value
    MyMessage errMsg(CHILD_ERRID,V_DISTANCE); // use distance to keep track of changing value
    double ppl = ((double)PULSE_FACTOR / 1000.0);    // Pulses per liter
    unsigned int oldBatteryPcnt = 0;          // check if changed
    unsigned int minsendcnt = MIN_SEND_FREQ;  // counter for keeping minimum intervals between sending
    unsigned int maxsendcnt = MAX_SEND_FREQ;  // counter for keeping maximum intervals between sending 
    unsigned int treshold = 512;              // threshold value when to swap on/off for pulse
    unsigned long pulseCount = 0;             // total volume of this pulse meter (value stored/received on gateway on pcReceived)
    unsigned long oldPulseCount = 0;          // to see if we have received something
    boolean pcReceived = false;               // received volume from prior reboot
    boolean onoff = false;                    // sensor value above/below treshold 
    unsigned int intervalcnt = 0;             // number of cycles between last period (for flow calculation)
    double flow = 0;                          // maintain flow
    double oldflow = 0;                       // keep prior flow (only send on change)
    unsigned int learntime=LEARN_TIME*2;      // timer for learning period
    unsigned int learnlow = 1023;             // lowest value found during learning
    unsigned int learnhigh = 0;               // highest value found during learning
    boolean learnsaved = false;               // have saved learned value
    unsigned long pingcnt = 0;
    unsigned long errcnt = 0;                 // error count
    unsigned int errcnt2 = 0;                 // error counter set to 0 when sending is ok
    void(* resetFunc) (void) = 0;//declare reset function at address 0 (for rebooting the Arduino)
    void setup() {    
      // make sure a few vars have the right init value after software reboot
      pingcnt = 0;
      pcReceived = false;
      pulseCount = oldPulseCount = 0;
      // setup hardware
      pinMode(SENSOR_POWER, OUTPUT); 
      digitalWrite(SENSOR_POWER, LOW);
      pinMode(LEARN_LED_PIN, INPUT);      // default is input because this pin also has SW2 of battery block
      // Fetch last known pulse count value from gateway
      request(CHILD_ID, V_VAR1);
      // Fetch threshold value from EE prom
      treshold = readEeprom(EE_TRESHOLD);
      if (treshold<30 || treshold>1000) treshold = 512;   // wrong value in EEprom, take default
      Serial.print("Treshold: ");
      // use the 1.1 V internal reference for the battery and IR sensor
    #if defined(__AVR_ATmega2560__)
      analogRead(IR_SENSE_PIN); // settle analogreference value
      wait(CHECK_FREQUENCY); // wait a bit
    void presentation()  {
      // Send the sketch version information to the gateway and Controller
      sendSketchInfo("Water Meter", "1.2");
      // Register this device as Waterflow sensor
      present(CHILD_ID, S_WATER);      
      present(CHILD_PINGID, S_DISTANCE); 
      present(CHILD_ERRID, S_DISTANCE);
    void loop() {
      if (digitalRead(LEARN_SWITCH_PIN)==LOW) {
        pinMode(LEARN_LED_PIN, OUTPUT);
        digitalWrite(SENSOR_POWER, HIGH);
        intervalcnt = 0;
      } else {
        learnlow = 1023;
        learnhigh = 0;
        pinMode(LEARN_LED_PIN, INPUT);
    void learn_loop() {
      // will run into this loop as long as we are learning
      unsigned int sensorValue = analogRead(IR_SENSE_PIN);
      Serial.print("IR: ");
      if (learntime>0) {
        // still learning
        learnsaved = false;    
        digitalWrite(LEARN_LED_PIN, !digitalRead(LEARN_LED_PIN));  // blink led
        if (sensorValue < learnlow) {
          learnlow = sensorValue;
          Serial.println(" Lowest");
        } else if (sensorValue > learnhigh) {
          learnhigh = sensorValue;
          Serial.println(" Highest");
        } else Serial.println();
      } else {
        if (!learnsaved) {
          treshold = (learnhigh + learnlow)/2;
          Serial.print("Treshold: ");
          storeEeprom(EE_TRESHOLD, treshold);
        learnsaved = true;
        // just display using LED
        digitalWrite(LEARN_LED_PIN, sensorValue>treshold);
        Serial.println((sensorValue>treshold ? " on" : " off"));
    void normal_loop() { 
      unsigned long start_loop = millis();    // to allow adjusting wait time
      // we start doing a measurement
      digitalWrite(SENSOR_POWER, HIGH);
      unsigned int sensorValue = analogRead(IR_SENSE_PIN);
      digitalWrite(SENSOR_POWER, LOW); 
      #ifdef MY_DEBUG_DETAIL
      Serial.print("IR: ");
      boolean nowvalue = onoff;
      if (onoff && (sensorValue<treshold-TRESHOLD_MARGIN)) nowvalue = false;
      if (!onoff && (sensorValue>treshold+TRESHOLD_MARGIN)) nowvalue = true;
      if (nowvalue != onoff) {
        // we have a pulse, only count on upwards pulse
        onoff = nowvalue;
        if (onoff) {
          #ifdef MY_DEBUG
          Serial.print("p: ");
    // Only send values at a maximum frequency or woken up from sleep
      if (minsendcnt>0) minsendcnt--;
      if (maxsendcnt>0) maxsendcnt--;
      // send minimum interval when we have pulse changes or if we had some flow the prior time or send on timeout
      if ((minsendcnt==0 && (pulseCount != oldPulseCount)) || (minsendcnt==0 && oldflow != 0) || maxsendcnt==0) {
        if (!pcReceived) {   //Last Pulsecount not yet received from controller, request it again
          Serial.print("Re-request var1 ..");
          request(CHILD_ID, V_VAR1);
    // Prevent flooding the gateway with re-requests,,, wait at least 1000 ms for gateway (cannot be sleep or smartSleep
        minsendcnt = MIN_SEND_FREQ;
        maxsendcnt = MAX_SEND_FREQ;
        sensorValue = analogRead(BATTERY_SENSE_PIN);
        int batteryPcnt = sensorValue / 10;
        // 1M, 470K divider across battery and using internal ADC ref of 1.1V
        // Sense point is bypassed with 0.1 uF cap to reduce noise at that point
        // ((1e6+470e3)/1e6)*1.1 = Vmax = 1.67 Volts
        // 1.67/1023 = Volts per bit = 0.00158065
        Serial.print("Battery %: ");
        if (oldBatteryPcnt != batteryPcnt) {
          oldBatteryPcnt = batteryPcnt;
        double volume = ((double)pulseCount/((double)PULSE_FACTOR));      
        flow = ((double) (pulseCount-oldPulseCount)) * (60000.0 / ((double) intervalcnt*(double) CHECK_FREQUENCY)) / ppl;  // flow in liter/min
        #ifdef MY_DEBUG
        Serial.println(volume, 3);
        bool b = send(lastCounterMsg.set(pulseCount));  // Send  pulsecount value to gw in VAR1
        if (b) errcnt2=0; else { errcnt++; errcnt2++; }
        b = send(volumeMsg.set(volume, 3));               // Send volume (set function 2nd argument is resolution)
        if (b) errcnt2=0; else { errcnt++; errcnt2++; }
        b = send(flowMsg.set(flow, 2));                   // Send flow value to gw
        if (b) errcnt2=0; else { errcnt++; errcnt2++; }
        b = send(pingMsg.set(pingcnt));                   // ensure at least this var has a different value
        if (b) errcnt2=0; else { errcnt++; errcnt2++; }
        b = send(errMsg.set(errcnt2+((float) errcnt2/100),2));    // ensure we always send error count
        if (b) errcnt2=0; else { errcnt++; errcnt2++; }
        oldPulseCount = pulseCount;
        intervalcnt = 0;
        oldflow = flow; 
        if (errcnt2>= (5*RESETMIN)) {
          resetFunc(); //call reset to reboot the Arduino
    // calculate how long it took to process all of this. then go to sleep for the remaining period
      unsigned long end_loop = millis();
      if (end_loop - start_loop < CHECK_FREQUENCY)
        sleep(CHECK_FREQUENCY - (end_loop > start_loop ? end_loop - start_loop : 0));
    void receive(const MyMessage &message) {
      if (message.type==V_VAR1) {
        unsigned long gwPulseCount=message.getULong();
        pulseCount += gwPulseCount;
        oldPulseCount += gwPulseCount;
        Serial.print("Received last pulse count from gw:");
        pcReceived = true;
    void storeEeprom(int pos, int value) {
        // function for saving the values to the internal EEPROM
        // value = the value to be stored (as int)
        // pos = the first byte position to store the value in
        // only two bytes can be stored with this function (max 32.767)
        saveState(pos, ((unsigned int)value >> 8 ));
        saveState(pos, (value & 0xff));
    int readEeprom(int pos) {
        // function for reading the values from the internal EEPROM
        // pos = the first byte position to read the value from 
        int hiByte;
        int loByte;
        hiByte = loadState(pos) << 8;
        loByte = loadState(pos);
        return (hiByte | loByte);

  • Mod

    Great work @bart59 !
    Do you have any indication on how long battery life you will get with this setup?

  • @mfalkvidd - I did measure the average current consumption at the time, but I not remember the exact value. I believe it was well below the 0.5 mA. The sensor has been up and running on the same single 1.5V AA battery for 30 days now and the batt percentage still shows 93%.

  • I hope this is not off topic but I'm trying to read our gas meter - but....I cannot use a photo sensor or a hall sensor or a reed switch (the meter is outside and there is no magnet in it). I was able to get some good data using a magnetometer (https://www.sparkfun.com/tutorials/301) using an arduino. But I tink from what I am told is the arduino isn't big enough to handle the code I need to use to change the data (x axis, y axis, z axis) into a pulse but will work on a pi.

    My question is am I missing something (hardware guy, not software)? Can I use a Pi for a sensor (it has the inputs and room), all the code on this site is for arduinos. Could I have the Pi output a pulse to an arduino? Am I over thinking this?

  • @dpcreel. I would be surprised the Arduino could not handle the HMC5883L magnetometer from Sparkfun. The I2C protocol is natively supported and you only need to analyse numbers coming from the 3-Axis to decide when the wheels inside the gas meter turn. I think the position of the sensor will be very critical, but the code should not be too complex. Arduino's are typically limited in handling much data (there is only 2000 bytes of RAM in the ATmega328), but your code should not need much RAM space. The program size can be 32 KB which should be enough.

    If you want to go for the PI, there are I2C libraries out there you could use and I would then bypass the Mysensors gateway alltogether and connect an ethernet cable to the PI and use the MQTT protocol to talk to your home controller.


  • @bart59 The Arduino works fine with the HMC5883L, I got some good data from it and was able to "see" the gas meter movements very well. I am not able to write code (hardware guy) to change this data to a pulse for MySensors or whatever it needs. I just want to be able to read my gas meter with the HMC5883L. I did find some code in python that works on the pi, that's why I mentioned it. I'm a hack at software.

  • Hi
    I am trying to use the subject code with pulse water meters and hope someone can help to figure out what needs to be adjusted to get more accurate data.

    My setup:
    Gateway ESP8266 (NodeMCU) + NRF24 -> Connected to Domoticz
    Sensor node: Arduino Uno + NRF24
    Default codes from Build. Test sensors so far work great.

    Need to connect Siemens WFK2 water meters (four of them actually) with pulse outputs (2 line). According to data sheet (link text) there are two types: reed output or NAMUR.

    To start with, I connected the reed output of the water meter via 10k resistor to +5V, GND and D3. Again, according to data sheet, for every 10l the water meter should give an impulse (e.g. connect the switch). Taking this into account I have adjusted pulse factor to 100 and based on Nominal Flow Rate (Max Flow Rate impossible in my case) limited Max Flow to 25 l/min. This setup works, but I definitely get wrong flow values (e.g. with constant flow of 6l/min serial monitor and domoticz report anything between 12-15l/min) and also wrong water usage m3 and litre usage in Domoticz.

    When trying to debug, found out following behaviour (must be connected to Pulse length an Qn from data sheet IMHO):
    with each turn it indeed switches on, e.g. shortens the contacts which generates pulse for the sensor, however it takes up to 2-4 litres until switch is in the off state.

    As a result you might have a situation when meter switches on, one closes the tap, and the signal is on for minutes/hours until tap is again opened and 2-4 litres have been used, after which signal will switch off.

    Do I understand correctly that the debouncer which should take care of similar situations is not ready for this?

    thanks in advance for support

  • Hi Aram

    The original code from the mysensors site does not handle your situation very well (indeed because the switch staying on or off for a long time). You can use my code (see my post further up this discussion). In my case I have a pulse every 1 liter.

    In your case you only have 1 pulse every 10 liters, which means you have to take a much longer period to calculate the flow correctly. Basically you have to set MIN_SEND_FREQ to a higher value. The flow is calculated based on the number of pulses in a given time period. Example: with 6 l/min you have to calculate this value only once every 5 minutes (=30 liter = 3 pulses from your Siemens meter) instead of every 30 seconds as I do. So if MIN_SEND_FREQ = 600 (every 5 minutes) your flow is calculated as:

    flow = ((double) (pulseCount-oldPulseCount)) * (60000.0 / ((double) intervalcnt*(double) CHECK_FREQUENCY)) / ppl;

    In the example above (pulseCount-oldPulseCount) = 3 pulses
    ppl = 0.1
    intervalcnt = MIN_SEND_FREQ = 600
    ==> flow is 6 l/min