Hello,
Still programming noob here, so sorry for the simple question.
I am trying to use a XTM18S wattmeter (gives pulses) to get power use via MQTT to Home assistant,
I found some examples online and used the code but they are a few years old and some programming rules seemed to have changed, and I would like to request some help in updating it.
I played around with the suggested changes but I dont know enough to get it to work (im more of a copy/paste frankenstein code kind of guy thats flying blind 
)
The code I use (dont worry about the MQTT passwords, gona change that all later)
/**
* This script is based on these sources:
*
* To count pulses using interruptions: https://github.com/mysensors/MySensors/blob/master/examples/EnergyMeterPulseSensor/EnergyMeterPulseSensor.ino
* To connect to Wifi and publish MQTT messages: https://github.com/knolleary/pubsubclient/blob/master/examples/mqtt_esp8266/mqtt_esp8266.ino
*
* 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.
*
*******************************
*
* DESCRIPTION
* Use this sensor to measure kWh and Watt of your house meter.
* You need to set the correct pulsefactor of your meter (pulses per kWh).
* Reports every SEND_FREQUENCY miliseconds: pulses counting, kWh and Watt to different MQTT topics.
*
*/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Update these with values suitable for your network.
/************************* WiFi Access Point *********************************/
const char* ssid = "SSID";
const char* password = "PASSWORD";
/**************************** MQTT Broker ************************************/
const char* mqtt_server = "192.168.11.99"; // example: "192.168.0.8"
const char* mqtt_username = "arduino";
const char* mqtt_password = "mQTT5-ardui";
const char* mqtt_topic_watt = "ESP-energy-01/watt";
const char* mqtt_topic_kwh = "ESP-energy-01/kwh";
const char* mqtt_topic_pulse = "ESP-energy-01/pulse";
// Define the ISR function
void ICACHE_RAM_ATTR ISRoutine() {
// Your interrupt handling code here
}
#define DIGITAL_INPUT_SENSOR 12 // The digital input you attached S0+ D6 in Wemos D1 mini
#define PULSE_FACTOR 2000 // Nummber of pulses per kWh of your meeter
#define MAX_WATT 10000 // Max watt value to report. This filters outliers.
unsigned long SEND_FREQUENCY = 20000; // Minimum time between send (in milliseconds)
double ppwh = ((double)PULSE_FACTOR)/1000; // Pulses per watt hour
volatile unsigned long pulseCount = 0;
volatile unsigned long lastBlink = 0;
volatile unsigned long watt = 0;
unsigned long oldWatt = 0;
double oldKwh;
unsigned long lastSend;
WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
char wattString[6];
char kwhString[6];
char pulseCountString[6];
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
// Setup a MQTT subscription
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client", mqtt_username, mqtt_password)) {
Serial.println("connected");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup()
{
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
// 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 loop()
{
if (!client.connected()) {
reconnect();
}
client.loop();
unsigned long now = millis();
// Only send values at a maximum frequency
bool sendTime = now - lastSend > SEND_FREQUENCY;
if (sendTime) {
// New watt value has been calculated
if (watt != oldWatt) {
// Check that we dont get unresonable large watt value.
// could hapen when long wraps or false interrupt triggered
if (watt<((unsigned long)MAX_WATT)) {
// convert to a string with 2 digits before the comma and 2 digits for precision
dtostrf(watt, 4, 1, wattString);
client.publish(mqtt_topic_watt,wattString); // Publish watt to MQTT topic
}
Serial.print("Watt:");
Serial.println(wattString);
oldWatt = watt;
dtostrf(pulseCount, 4, 1, pulseCountString); // To Do: convert int to str, but not like this
client.publish(mqtt_topic_pulse,pulseCountString); // Publish pulses to MQTT topic
double kwh = ((double)pulseCount/((double)PULSE_FACTOR));
// convert to a string with 2 digits before the comma and 2 digits for precision
dtostrf(kwh, 2, 2, kwhString);
client.publish(mqtt_topic_kwh,kwhString); // Publish kwh to MQTT topic
oldKwh = kwh;
lastSend = now; // once every thing is published we update the send time
}
}
}
void onPulse()
{
unsigned long newBlink = micros();
unsigned long interval = newBlink-lastBlink;
if (interval<10000L) { // Sometimes we get interrupt on RISING
return;
}
watt = (3600000000.0 /interval) / ppwh;
lastBlink = newBlink;
pulseCount++;
}
This compiles fine, but I get the following error in serial monitor;
...
WiFi connected
IP address:
192.168.11.199
ISR not in IRAM!
User exception (panic/abort/assert)
--------------- CUT HERE FOR EXCEPTION DECODER ---------------
Abort called
stack>>>
When I do some googling I found this information (seems to have been a change since core 2.5.0
I don’t want to re-open a solved issue, but I discovered you just need to add ICACHE_RAM_ATTR in front of your ISR function to solve this issue. It tells the compiler to keep the ISR function in memory and is required for ESP core 2.5.1 and later.
But for the life of me I cant understand exactly what I have to change in my code to update it to this new way 
Any chanse any codeninja can quickly help me on my way here ??
thank you in advance,
Hans