#include <WiFi.h>
#include <PubSubClient.h>
#define TRIGGER_PIN 5 // Pin to trigger the ultrasonic sensor
#define ECHO_PIN 18 // Pin to receive echo from the ultrasonic sensor
//-------IBM Watson IoT Platform Credentials------
#define ORG "3mnch4" // IBM Watson IoT Platform organization ID
#define DEVICE_TYPE "abcd" // Device type registered in IBM Watson IoT Platform
#define DEVICE_ID "1234" // Device ID registered in IBM Watson IoT Platform
#define TOKEN "12345678" // Authentication token for the device
char server[] = ORG ".messaging.internetofthings.ibmcloud.com"; // Server name
char publishTopic[] = "iot-2/evt/data/fmt/json"; // Topic name and type of event to perform
//and format in which data is sent
char authMethod[] = "use-token-auth"; // Authentication method
char clientId[] = "d:" ORG ":" DEVICE_TYPE ":" DEVICE_ID; // Client ID
//-----------------------------------------
WiFiClient wifiClient; // Instance for WiFi client
PubSubClient client(server, 1883, wifiClient); // PubSubClient instance with server, port,
//and WiFi credentials
void setup()
{
Serial.begin(115200);
pinMode(TRIGGER_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
delay(10);
Serial.println();
wificonnect();
mqttconnect();
}
void loop()
{
long duration, distance;
digitalWrite(TRIGGER_PIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIGGER_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIGGER_PIN, LOW);
duration = pulseIn(ECHO_PIN, HIGH);
distance = (duration / 2) / 29.1; // Calculate distance in cm
PublishData(distance);
if (!client.loop())
{
mqttconnect();
}
}
/*.....................................Publishing to IBM Watson IoT Platform...............................*/
void PublishData(long distance)
{
mqttconnect();
String payload = "{\"distance\":";
payload += distance;
payload += "}";

Serial.print("Sending payload: ");
Serial.println(payload);
if (client.publish(publishTopic, (char*) payload.c_str()))
{
Serial.println("Publish OK");
}
else
{
Serial.println("Publish failed");
}
}
void mqttconnect()
{
if (!client.connected())
{
Serial.print("Connecting client to ");
Serial.println(server);
while (!client.connect(clientId, authMethod, TOKEN))
{
Serial.print(".");
delay(500);
}
Serial.println("Client connected");
initManagedDevice();
}
}
void initManagedDevice()
{
Serial.println("Subscribing to commands...");
if (client.subscribe("iot-2/cmd/command/fmt/String"))
{
Serial.println("Subscribe OK");
}
else
{
Serial.println("Subscribe failed");
}
}
void wificonnect()
{
Serial.print("Connecting to WiFi");
WiFi.begin("Wokwi-GUEST", "",6);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("Connected to WiFi");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}