Wemos D1 mini to send MQTT messages when motion is detected

Using Wemos D1 mini to send MQTT messages when motion is detected through connected HF sensor.
The HF sensor has 230V output that is transformed to 3.3V using a small 230V to 3.3V power supply.

http://www.hobbyelektronik.nu/forum/viewtopic.php?f=13&t=37

#include <ESP8266WiFi.h>
#include <ESP8266mDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>
#include <PubSubClient.h>

const char* version = "HF_motion_mqtt 1.0";
const char* date_name = "2017-06-10 Hans Palm";

// Code for using Wemos D1 Mini with a HF motion detector
// 3.3V input on D1 when sensor is trigged
// MQTT messages according to outTopic* are sent when D1 input becomes active = high
// D1 must become low before new activation can occur

// When activated, MQTT messages similar to the following are sent:
// Activates kitchen timer:
//
//   mosquitto_pub -h localhost -t "KTActivate" -m "1"
//
// Activates Ikea Trådfri lamp above kitchen table
//
// mosquitto_pub -h localhost -t "tradfri_kbordet" -m "1"

// Wifi settings
const char* ssid = "SSID";
const char* password = "password";
const char* host = "OTAHOSTNAME";

// The follwing parameters are only required for fixed IP, otherwise uncomment, also uncomment WiFi.config(ip, gateway, subnet)
IPAddress ip(192, 168, 0, 170);
IPAddress gateway(192, 168, 0, 1);
IPAddress subnet(255, 255, 255, 0);

// MQTT server and topic settings
const char* mqtt_server = "192.168.0.xxx";
const char* clientID = "MotionKitchenOTA";
const char* outTopic_KTActivate = "KTActivate";
const char* outTopic_tradfri_kbordet = "tradfri_kbordet";

const char* inTopic = "TBD"; // Not used in this sketch

bool trigged = false;

WiFiClient espClient;
PubSubClient client(espClient);

void setup()
{
  Serial.begin(115200);
  delay(10);
  Serial.println("setup started ");

  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(D1, INPUT);

  // Connect to WiFi network
  WiFi.config(ip, gateway, subnet); // Only required for fixed IP
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }


 ArduinoOTA.setHostname(host);
 ArduinoOTA.onStart([]() {
    String type;
    type = "sketch";
    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("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void callback(char* topic, byte* payload, unsigned int length) {
  // Check incoming message using really ugly code
  String nstring = "";
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
    nstring = String (nstring + (char)payload[i]);
  }
  nstring = String (nstring + '\0');
  Serial.println("");
  Serial.print("nstring = ");
  Serial.println(nstring);
  int value;
  if (String(topic + '\0' == inTopic)) {
    value = nstring.toInt(); // (long) 0 is returned if unsuccessful)
    if (value > 0 ) {
      // Serial.print("TBD value change to ");
      Serial.print(value);
      Serial.println(" requested");
      // TBD
    }
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(clientID)) {
      Serial.println("connected");
      // Once connected, publish an announcement...
      // ... and resubscribe
      client.subscribe(inTopic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void loop()
{
  ArduinoOTA.handle();

  // Check if a client has connected
  if (!client.connected()) {
    reconnect();
  }

  // Perform PubSubClient tasks
  client.loop();

  int input = digitalRead(D1);
  digitalWrite(LED_BUILTIN, !input);

  if (input) {
    if (!trigged) {
      trigged = true;
      char msg[50];
      snprintf (msg, 75, "1");
      client.publish(outTopic_tradfri_kbordet, msg);
      snprintf (msg, 75, "1");
      client.publish(outTopic_KTActivate, msg);
    }
  } else {
    trigged = false;
  }

  delay(10); // Probably not required
}