UDP Issues - UDP message to SignalK from ESP8266

[PaddyB]

I've got it working here just with  dummy message, actually 2 of esp8266 sending SOG & COG messages. 

Code is just a messy try out but works this end. The code can be uploaded over the air as well, no need to plug into the 8266 - upload over wifi, really handy. 
http://esp8266.github.io/Arduino/version...dates.html

Another way to go is to use easyesp and send the data as MQTT which openplotter can then map to a signalk update. 

Code:

#include <ESP8266WiFi.h>

#include <ESP8266mDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>

const char* ssid = "openplotter";
const char* password = "12345678";

unsigned int localPort = 55557;      //  port to  send  UDP packets



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

void setup() {
 Serial.begin(115200);
 Serial.println("Booting");
 WiFi.mode(WIFI_STA);
 WiFi.begin(ssid, password);
 while (WiFi.waitForConnectResult() != WL_CONNECTED) {
   Serial.println("Connection Failed! Rebooting...");
   delay(5000);
   ESP.restart();
 }

 // Port defaults to 8266
 // ArduinoOTA.setPort(8266);

 // Hostname defaults to esp8266-[ChipID]
 // ArduinoOTA.setHostname("myesp8266");

 // No authentication by default
 // ArduinoOTA.setPassword("admin");

 // Password can be set with it's md5 value as well
 // MD5(admin) = 21232f297a57a5a743894a0e4a801fc3
 // ArduinoOTA.setPasswordHash("21232f297a57a5a743894a0e4a801fc3");

 ArduinoOTA.onStart([]() {
   String type;
   if (ArduinoOTA.getCommand() == U_FLASH)
     type = "sketch";
   else // U_SPIFFS
     type = "filesystem";

   // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
   Serial.println("Start updating " + type);
 });
 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();
 Serial.println("Ready");
 Serial.print("IP address: ");
 Serial.println(WiFi.localIP());
 Udp.begin(localPort);
 pinMode(2, OUTPUT);
}

void loop() {
 ArduinoOTA.handle();
 
 digitalWrite(2, HIGH); // turn the LED on (HIGH is the voltage level)
 delay(500); // wait for 1/2 second
 digitalWrite(2, LOW); // turn the LED off by making the voltage LOW
 delay(1000);

 
 int value = random(20);  // create a random vaue between 0 and 20 to simulate SOG
 String tempString = "{\"updates\": [{\"$source\": \"OPsimulation\",\"values\":[ {\"path\":\"navigation.courseOverGroundTrue\",\"value\":\"";   //  create 1st part of signalk string
     
 tempString += String(value);  //add simulated SOG to string
 tempString += "\"}]}]}\n" ;   // finish the signelK string

 char  replyPacekt[tempString.length()+1] ;  //initialise char array for UDP

 tempString.toCharArray(replyPacekt, tempString.length()+1);   // add the signalk string to char array


// send the char array as UDP
 IPAddress  ip = IPAddress(10,10,10,1);
 Udp.beginPacket(ip, localPort);    //signalk server on Pi listens on 10.10.10.1 port 55557
 Udp.write(replyPacekt);
 Udp.endPacket();

}