I have just posted an example config to run HA and integrate with OpenEnergyMonitor Raspberry Pi based emonPi energy monitor:
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I have just ordered my Emon shield, and intend on using an ESP8266 as the radio.
it will take in the serial string, parse it, and post the data to EmonCMS and publish to MQTT as well.
should be a simpler and cheaper setup, with built in wifi.
I will post again once i have it running.
cheers.
Nice! Let us know how you get on. We have also been working on an ESP8266 to Emoncms link. It’s still very much in development:
Please join in the conversation on the OpenEnerygMonitor forums:
So it just gets details from the serial line?
I was hoping it would have the RFM radio integrated.
I have it up and running now, just piggy-backing serial, and posting to emonCMS, as well as publishing to MQTT. I can post the code if anyone is interested, just needs a bit of cleaning up first!
Correct, we are moving towards using direct ESP8266 > Wifi > Emoncms rather than RFM to reduce the number of possible failure points.
However, there is certainly a need for an RFM > MQTT wifi-bridge, please share your code and experience over on the OpenEnergyMonitor forums.
basically i grab the serial line, split it by the seperator (" ") and use the first digit as the nodeId, then the rest are sent via MQTT (using the pubsub library). I also use OTA programming, as that allows me to easily update the software as i want, and not worry about dis/reconnecting. It uses Wifi manager to setup wireless via your phone. I think all libraries are available in the library manager. And the code could probably use some cleaning up…
I have the code below - you just have to attach the gnd and Tx from the emonTx to the Rx on the ESP. I am currently using a nodeMCU v1.0. This has been expanded from tzapu’s gateway.
#include <PubSubClient.h>
#include <ESP8266WiFi.h> //https://github.com/esp8266/Arduino
#include <EEPROM.h>
#include <ESP8266WebServer.h>
#include <DNSServer.h>
#include <WiFiManager.h> //https://github.com/tzapu/WiFiManager
#include <ESP8266mDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>
//Used to test input during development
#include <Ticker.h>
Ticker ticker;
//varaibles to store each data set
const int DATASLOTS = 13;
String values[DATASLOTS];
// Setup MQTT Details.
byte mqtt_server[] = { 10, 1, 1, 2 };
WiFiClient emonTx_ESPGateway;
PubSubClient client(emonTx_ESPGateway);
long lastMsg = 0;
char msg[50];
char cnodeId[10];
char cdata[10];
int value = 0;
#include "config.h"
//contains
//const char* emoncmsKey = "whateveryourkeyis...";
//emoncoms
const char* host = "emoncms.org";
String inputString = ""; // a string to hold incoming data
boolean stringComplete = false; // whether the string is complete
String topic = "";
String c1 = "0";
String c2 = "0";
String c3 = "0";
String v = "0";
void serialEvent();
bool isInt(String str);
void sendToEmonCMS(String nodeId, String data);
String getValue(String data, char separator, int index)
{
int maxIndex = data.length()-1;
int j=0;
String chunkVal = "";
for(int i=0; i<=maxIndex && j<=index; i++)
{
if(data[i]==separator)
{
j++;
if(j>index)
{
chunkVal.trim();
return chunkVal;
}
chunkVal = "";
}
else {
chunkVal.concat(data[i]);
}
}
}
// used to test when no appropriate data is being recieved.
void injectData() {
inputString = "10 1163.90 243.00 12376.00 0.00 220.22";
stringComplete = true;
Serial.println("injected");
}
void setup() {
//ticker.attach(2, injectData);
// make sure the serial baudrate is the same as on your serial sending device
Serial.begin(9600);
WiFiManager wifi;
wifi.setTimeout(120); //so if it restarts and router is not yet online, it keeps rebooting and retrying to connect
if(!wifi.autoConnect()) {
Serial.println("failed to connect and hit timeout");
delay(1000);
//reset and try again
ESP.reset();
delay(5000);
}
// Initiate MQTT client
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
inputString.reserve(200);
/*---------Start OTA Code---------------------*/
// Port defaults to 8266
// ArduinoOTA.setPort(8266);
ArduinoOTA.setHostname("EmonTx-ESPGateway");
// No authentication by default
// ArduinoOTA.setPassword((const char *)"123");
ArduinoOTA.onStart([]() {
Serial.println("Start");
});
ArduinoOTA.onEnd([]() {
Serial.println("\nEnd");
});
ArduinoOTA.onProgress([](unsigned int progress, unsigned int total) {
Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
});
ArduinoOTA.onError([](ota_error_t error) {
Serial.printf("Error[%u]: ", error);
if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
else if (error == OTA_END_ERROR) Serial.println("End Failed");
});
ArduinoOTA.begin();
/*-----------End OTA code---------------------*/
Serial.println("Ready");
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
}
void loop() {
String subString;
int spacePos;
ArduinoOTA.handle();
//MQTT Connection Handling
if (!client.connected()) {
reconnect();
}
client.loop();
//MQTT Heartbeat
long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
++value;
snprintf (msg, 75, "hello world #%ld", value);
Serial.print("Publish message: ");
Serial.println(msg);
client.publish("outTopic", msg);
}
// check serial line for new information
serialEvent();
// Process the serial data, post to emonCMS and publish to MQTT
if (stringComplete) {
String serialData = inputString;
spacePos = serialData.indexOf(" ");
if (spacePos != -1) {
//found a space, try to extract nodeId
String nodeId = serialData.substring(0, spacePos);
Serial.println(nodeId);
if (isInt(nodeId)) {
Serial.println("number");
String data = serialData.substring(spacePos + 1);
data.replace(" ", ",");
delay(0);
sendToEmonCMS(nodeId, data);
delay(0);
//Chop up the serial data into individual entities, and publish to MQTT
for (int x = 0; x <= DATASLOTS; x++) {
subString = getValues(serialData, ' ', x);
if (subString != "error") {
values[x] = subString;
//Dynamic posting, by order of recieved data
//MQTTPost("emonTx/Serial", values[x]);
}
else {
x = DATASLOTS + 1;
}
}
// Publish data with appropriate topics.
MQTTPost("emonTx/" + nodeId + "/CT1", values[1] );
MQTTPost("emonTx/" + nodeId + "/CT2", values[2] );
MQTTPost("emonTx/" + nodeId + "/CT3", values[3] );
MQTTPost("emonTx/" + nodeId + "/CT4", values[4] );
MQTTPost("emonTx/" + nodeId + "/Vrms", values[5] );
//Reset the serial inputs
stringComplete = false;
inputString = "";
}
}
}
}
// function to simplify publishing to MQTT - basically just typecasts the strings as char
void MQTTPost (String topic, String data) {
client.publish( (char*) topic.c_str(), (char*) data.c_str());
}
/*
SerialEvent occurs whenever a new data comes in the
hardware serial RX. This routine is run between each
time loop() runs, so using delay inside loop can delay
response. Multiple bytes of data may be available.
*/
void serialEvent() {
while (Serial.available()) {
char inChar = (char)Serial.read();
if (inChar == '\n') {
stringComplete = true;
return;
} else {
inputString += inChar;
}
}
}
//check if string is all digits
bool isInt(String str) {
for (byte i = 0; i < str.length(); i++)
{
if (!isDigit(str.charAt(i))) {
return false;
}
}
return true;
}
// Post data to EmonCMS
void sendToEmonCMS(String nodeId, String data) {
WiFiClient client;
const int httpPort = 80;
if (!client.connect(host, httpPort)) {
Serial.println("connection failed");
return;
}
// We now create a URI for the request
String url = "/input/post.json?node=";
url += nodeId;
url += "&apikey=";
url += emoncmsKey;
url += "&csv=";
url += data;
Serial.println(url);
// This will send the request to the server
client.print(String("GET ") + url + " HTTP/1.1\r\n" +
"Host: " + host + "\r\n" +
"Connection: close\r\n\r\n");
delay(10);
// Read all the lines of the reply from server
while (client.available()) {
String line = client.readStringUntil('\r');
//Serial.print(line);
}
}
/*-----------MQTT Functions---------------------*/
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("emonTx-Gateway", "Connected to MQTT server");
// ... and resubscribe to appropriate Topics
client.subscribe("emonTx-Gateway");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void callback(char* chartopic, byte* payload, unsigned int length) {
char p[length + 1];
memcpy(p, payload, length);
p[length] = NULL;
String message(p);
String topic(chartopic);
Serial.print("Message arrived [");
Serial.print(chartopic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
}
/*-----------End MQTT Functions---------------------*/
// Chop serial input based on a seperator charactex and index number
String getValues(String data, char separator, int index) {
int found = 0;
int strIndex[] = {
0, -1 };
int maxIndex = data.length()-1;
for(int i=0; i<=maxIndex && found<=index; i++){
if(data.charAt(i)==separator || i==maxIndex){
found++;
strIndex[0] = strIndex[1]+1;
strIndex[1] = (i == maxIndex) ? i+1 : i;
}
}
return found>index ? data.substring(strIndex[0], strIndex[1]) : "error";
}
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rasberrypi.org promoting OpenEnergyMonitor today via twitter so thought I would fan the flames of this thread to see if there are any interesting updates to post? Link to updated blog post:
Hi
I am looking to build something very similar using openenergy but I am slightly confused as I am not sure what to purchase. I want to keep the project as cheap as possible.
Any suggestions/help will be very much appreciated.
Thanks.
I’m not sure, but plan on trying to make an energy monitor using one I have
Hmm I had a look at the current sensor and it seems like I need to get emonshield.
Whats the shield for? I ordered a similar sensor on amazon, i believe it is read through the audio port
I thought it was the brains of transmitting the values to mqtt?
How do you use your sensor and where do you plug it to read the electricity readings?
I will have a go at setting it up and post my progress 
2 Likes
Have you made any progress? I am debating between this open source route and a prebuilt like the Sense.
Not yet, been busy with other projects, but checkout https://shop.openenergymonitor.com/ as uses this sensor
Yeh just wondering if anyone is using OpenEnergyMonitor and if it is really helping with energy consumption vs a thing like Sense which can track individual appliances (or so they claim)
Pretty sure there is a Bruh video on the sense, didn’t look that accurate