Humidity Sensor -> MQTT -> SignalK (data conversion)

[PaddyB]

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First of all....complete NUBE!!! That said, I have put together an Mega 2560 Arduino based board which is measuring solar panel current, voltage as well as a temperature and humidity sensor. I am using

WiFiEspClient espClient;
PubSubClient client(espClient);

to send the data to MQTT broker on OpenPlotter running on a RPi. Using the interface there I mapped MQTT messages to SignalK. I then started up Wilhelm used generic controls to display....all working and very cool. Then tried to use Temperature and Ratio Controls. The Wilhelm author Mr Bender discovered I was sending strings rather than numerical values through MQTT. 

I tried building the EspSigK example but I suspect because of the Mega 2560 getting build errors that are currently beyond my skill level to resolve. (error on some includes in EspSigK.h) At this point not sure if I should abandon the MQTT and go after the EspSigK? Any suggestions GREATLY appreciated. VR Anthony

So is it sending over Wifi or serial? Either way there'll be a way to send as signalk intead of mqtt - you could maybe try this function I pinched and tweaked, think it was from espsigk.  Not sure if that will work but worth a try, #include.... goes at the top then the WifiUDP above the setup. 
So to send just go >

"sendSigK("mytest.test", 12345 );"

You might need to add the json library, in the arduino IDE go into Sketch|include Library|manage libraries and search fo arduinojson, might be better not to add a beta librry, but go for an earlier one. 

Good luck, for a nube you seem to have hit the ground running!!! :

Code:

#include <ArduinoJson.h>
#include <WiFiUdp.h>


WiFiUDP Udp;        // A UDP instance to let us send and receive packets over UDP



void sendSigK(String sigKey, float data) {    //    send SigK via UDP *****************************************


 DynamicJsonBuffer jsonBuffer;
 //String deltaText;

 //  build delta message
 JsonObject& delta = jsonBuffer.createObject();

 //updated array
 JsonArray& updatesArr = delta.createNestedArray("updates");
 JsonObject& thisUpdate = updatesArr.createNestedObject();   //Json Object nested inside delta [...
 JsonArray& values = thisUpdate.createNestedArray("values"); // Values array nested in delta[ values....
 JsonObject& thisValue = values.createNestedObject();
 thisValue["path"] = sigKey;
 thisValue["value"] = data;

 thisUpdate["Source"] = "ESP11";

 // Send UDP packet
 Udp.beginPacket(remoteIp, remotePort);
 delta.printTo(Udp);
 delta.printTo(Serial);
 Serial.println();
 Udp.println();
 Udp.endPacket();
 delay(10);

 Serial.print("UDP sent. remoteIP = ");
 Serial.println(remoteIp);
 Serial.print("remote port = ");
 Serial.println(remotePort);
 Serial.print("Wifi mode = ");
 Serial.println(WiFi.getMode());


}