MQTT serial bridge with EspEasy

[Alan_37]

Hi,

Was wondering if there is a plugin to use Espeasy as an MQTT serial bridge to make a microcontroller
MQTT enabled via Esp.

Any ideas Please

[grovkillen]

Nothing like that is present no.

[TD-er]

Well you can post the raw data from a serial port to MQTT via the "Serial Proxy" plugin.
It does have a few limitations like you only can send a single init string (called at PLUGIN_READ) to trigger a read on the connected device and it does need to have a CRLF (or just CR, not 100% sure) to recognize it as a full line.

[Alan_37]

hi
Thanks for your reply and suggestions I came across
this simple ESP8266 (Arduino IdE) code that works 100% perfectly
it would be really great if someone can build a plugin from it

Code: Select all

#include <ESP8266WiFi.h>
#include <PubSubClient.h>

const char* ssid = "SSID";
const char* password = "Password";
const char* mqtt_server = "192.168.10.4";
const char* topic_rx = "uart/rx";
const char* topic_tx = "uart/tx";


const byte numChars = 100;
char receivedChars[numChars]; // an array to store the received data
boolean newData = false;

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
  Serial.begin(19200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void setup_wifi() {
  delay(10);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
}

void callback(char* topic, byte* payload, unsigned int length) {
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

String macToStr(const uint8_t* mac)
{
  String result;
  for (int i = 0; i < 6; ++i) {
    result += String(mac[i], 16);
    if (i < 5)
      result += ':';
  }
  return result;
}

void reconnect() {
  String clientName;
  clientName += "esp8266-";
  uint8_t mac[6];
  WiFi.macAddress(mac);
  clientName += macToStr(mac);
  clientName += "-";
  clientName += String(micros() & 0xff, 16);
  while (!client.connected()) {
    if (client.connect((char*) clientName.c_str())) { // random client id
      digitalWrite(BUILTIN_LED, LOW); // low = high, so this turns on the led
      client.subscribe(topic_rx); // callback: mqtt bus -> arduino
    } else {
      digitalWrite(BUILTIN_LED, HIGH); // high = low, so this turns off the led
      delay(5000);
    }
  }
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  recvWithEndMarker();
  showNewData();
}

void recvWithEndMarker() {
  static byte ndx = 0;
  char endMarker = '\n';
  char rc;
 
  while (Serial.available() > 0 && newData == false) {
    rc = Serial.read();

    if (rc != endMarker) {
      receivedChars[ndx] = rc;
      ndx++;
      if (ndx >= numChars) {
        ndx = numChars - 1;
      }
    }
    else {
      receivedChars[ndx] = '\0'; // terminate the string
      ndx = 0;
      newData = true;
    }
  }
}

void showNewData() {
  if (newData == true) {
    client.publish(topic_tx, receivedChars); // publish: arduino -> mqtt bus
    newData = false;
  }
}

[TD-er]

I edited your post to add code tags wrapping it.
That makes it a lot easier to read, or else all indents would be lost.

I looked at the code and it looks to me it is very much the same as the SerialProxy plugin does.
Only thing it doesn't do is redirecting the receiving messages published in the subscribed topic to the serial port.