Hi
My heat exchanger does only give one pulse / kWh which results in that there can be hours between the pulses. When doing the watt calculation micros are used and that counter overflow after 70minutes. See: https://www.arduino.cc/reference/en/language/functions/time/micros/
I have modified the sketch to use millis instead of micros when the time between the pulses are above one hour and micros if it is less than an hour.
I hope I did it correct 
Best regards
Peter Andersson
/*
* The MySensors Arduino library handles the wireless radio link and protocol
* between your home built sensors/actuators and HA controller of choice.
* The sensors forms a self healing radio network with optional repeaters. Each
* repeater and gateway builds a routing tables in EEPROM which keeps track of the
* network topology allowing messages to be routed to nodes.
*
* Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
* Copyright (C) 2013-2019 Sensnology AB
* Full contributor list: https://github.com/mysensors/MySensors/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.
*
*******************************
*
* REVISION HISTORY
* Version 1.0 - Henrik Ekblad
* Version 1.1 - Peter Andersson added millis watt calculation if time between pulses > 1h
*
* DESCRIPTION
* This sketch provides an example how to implement a LM393 PCB
* Use this sensor to measure kWh and Watt of your house meter
* You need to set the correct pulsefactor of your meter (blinks per kWh).
* The sensor starts by fetching current kWh value from gateway.
* Reports both kWh and Watt back to gateway.
*
* Unfortunately millis() won't increment when the Arduino is in
* sleepmode. So we cannot make this sensor sleep if we also want
* to calculate/report watt value.
* http://www.mysensors.org/build/pulse_power
*/
#define MY_REPEATER_FEATURE //Added
// Enable debug prints
#define MY_DEBUG
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
#include <MySensors.h>
#define DIGITAL_INPUT_SENSOR 3 // The digital input you attached your light sensor. (Only 2 and 3 generates interrupt!)
#define PULSE_FACTOR 1 // Number of blinks per of your meter. Normally 1000
#define SLEEP_MODE false // Watt value can only be reported when sleep mode is false.
#define MAX_WATT 100000 // Max watt value to report. This filters outliers. Normally 10000
#define CHILD_ID 1 // Id of the sensor child
uint32_t SEND_FREQUENCY =
20000; // Minimum time between send (in milliseconds). We don't want to spam the gateway.
double ppwh = ((double)PULSE_FACTOR)/1000; // Pulses per watt hour
bool pcReceived = false;
volatile uint32_t pulseCount = 0;
volatile uint32_t lastBlinkmicros = 0;
volatile uint32_t lastBlinkmillis = 0;
volatile uint32_t watt = 0;
uint32_t oldPulseCount = 0;
uint32_t oldWatt = 0;
double oldkWh;
uint32_t lastSend;
MyMessage wattMsg(CHILD_ID,V_WATT);
MyMessage kWhMsg(CHILD_ID,V_KWH);
MyMessage pcMsg(CHILD_ID,V_VAR1);
void setup()
{
// Fetch last known pulse count value from gw
request(CHILD_ID, V_VAR1);
// Use the internal pullup to be able to hook up this sketch directly to an energy meter with S0 output
// If no pullup is used, the reported usage will be too high because of the floating pin
pinMode(DIGITAL_INPUT_SENSOR,INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(DIGITAL_INPUT_SENSOR), onPulse, RISING);
lastSend=millis();
}
void presentation()
{
// Send the sketch version information to the gateway and Controller
sendSketchInfo("Energy Meter", "1.0");
// Register this device as power sensor
present(CHILD_ID, S_POWER);
}
void loop()
{
uint32_t now = millis();
// Only send values at a maximum frequency or woken up from sleep
bool sendTime = now - lastSend > SEND_FREQUENCY;
if (pcReceived && (SLEEP_MODE || sendTime)) {
// New watt value has been calculated
if (!SLEEP_MODE && watt != oldWatt) {
// Check that we don't get unreasonable large watt value.
// could happen when long wraps or false interrupt triggered
if (watt<((uint32_t)MAX_WATT)) {
send(wattMsg.set(watt)); // Send watt value to gw
}
Serial.print("Watt:");
Serial.println(watt);
oldWatt = watt;
}
// Pulse count value has changed
if (pulseCount != oldPulseCount) {
send(pcMsg.set(pulseCount)); // Send pulse count value to gw
double kWh = ((double)pulseCount/((double)PULSE_FACTOR));
oldPulseCount = pulseCount;
if (kWh != oldkWh) {
send(kWhMsg.set(kWh, 4)); // Send kWh value to gw
oldkWh = kWh;
}
}
lastSend = now;
} else if (sendTime && !pcReceived) {
// No pulse count value received. Try requesting it again
request(CHILD_ID, V_VAR1);
lastSend=now;
}
if (SLEEP_MODE) {
sleep(SEND_FREQUENCY);
}
}
void receive(const MyMessage &message)
{
if (message.type==V_VAR1) {
pulseCount = oldPulseCount = message.getLong();
Serial.print("Received last pulse count value from gw:");
Serial.println(pulseCount);
pcReceived = true;
}
}
void onPulse()
{
if (!SLEEP_MODE) {
uint32_t newBlinkmicros = micros();
uint32_t newBlinkmillis = millis();
uint32_t intervalmicros = newBlinkmicros-lastBlinkmicros;
uint32_t intervalmillis = newBlinkmillis-lastBlinkmillis;
if (intervalmicros<10000L && intervalmillis<10L) { // Sometimes we get interrupt on RISING
return;
}
if (intervalmillis<360000) { //Less then an hour since last pulse, use microseconds
watt = (3600000000.0 /intervalmicros) / ppwh;
} else {
watt = (3600000.0 /intervalmillis) / ppwh; //more then an hour since last pulse, use milliseconds as micros will overflow after 70min
}
lastBlinkmicros = newBlinkmicros;
lastBlinkmillis = newBlinkmillis;
}
pulseCount++;
}
