ESP32 + BME280, reporting in minutes.

1. Install the libraries

Install “esp32 by Espressif Systems”, “PubSubClient by Nick O’Leary” and “Adafruit BME280 Library” from Arduino IDE. Accept the prompted dependencies.

2. Connect the sensor

Connect the module over I2C. The sketch starts at address 0x76; change it to 0x77 if that is the address reported by your board.

Metrics sent: temperature, humidity, pressure_hpa

3. Generate a live credential

Create a Devicecamp device and choose ESP32 Arduino. Select this sensor before copying or downloading the sketch; the generated version contains the exact MQTT identity and topics.

4. Review the public template

MQTT_CLIENT_ID, MQTT_USERNAME and MQTT_PASSWORD are placeholders on this public page.

// Devicecamp ESP32 MQTT/TLS starter
// Install "esp32 by Espressif Systems" and "PubSubClient by Nick O'Leary".
// Also install "Adafruit BME280 Library" and its prompted dependencies.
// This file contains a live device credential. Do not commit or share it.

#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <PubSubClient.h>
#include <time.h>
#include <math.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

const char WIFI_SSID[] = "YOUR_WIFI_SSID";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";

const char MQTT_HOST[] = "mqtt.devicecamp.app";
const uint16_t MQTT_PORT = 8883;
const char MQTT_CLIENT_ID[] = "MQTT_CLIENT_ID";
const char MQTT_USERNAME[] = "MQTT_USERNAME";
const char MQTT_PASSWORD[] = "MQTT_PASSWORD";
const char TELEMETRY_TOPIC[] = "v1/devices/DEVICE_ID/telemetry";
const char STATUS_TOPIC[] = "v1/devices/DEVICE_ID/status";

const char DEVICECAMP_CA[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAwTzELMAkGA1UE
BhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2VhcmNoIEdyb3VwMRUwEwYDVQQD
EwxJU1JHIFJvb3QgWDEwHhcNMTUwNjA0MTEwNDM4WhcNMzUwNjA0MTEwNDM4WjBPMQswCQYDVQQG
EwJVUzEpMCcGA1UEChMgSW50ZXJuZXQgU2VjdXJpdHkgUmVzZWFyY2ggR3JvdXAxFTATBgNVBAMT
DElTUkcgUm9vdCBYMTCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBAK3oJHP0FDfzm54r
Vygch77ct984kIxuPOZXoHj3dcKi/vVqbvYATyjb3miGbESTtrFj/RQSa78f0uoxmyF+0TM8ukj1
3Xnfs7j/EvEhmkvBioZxaUpmZmyPfjxwv60pIgbz5MDmgK7iS4+3mX6UA5/TR5d8mUgjU+g4rk8K
b4Mu0UlXjIB0ttov0DiNewNwIRt18jA8+o+u3dpjq+sWT8KOEUt+zwvo/7V3LvSye0rgTBIlDHCN
Aymg4VMk7BPZ7hm/ELNKjD+Jo2FR3qyHB5T0Y3HsLuJvW5iB4YlcNHlsdu87kGJ55tukmi8mxdAQ
4Q7e2RCOFvu396j3x+UCB5iPNgiV5+I3lg02dZ77DnKxHZu8A/lJBdiB3QW0KtZB6awBdpUKD9jf
1b0SHzUvKBds0pjBqAlkd25HN7rOrFleaJ1/ctaJxQZBKT5ZPt0m9STJEadao0xAH0ahmbWnOlFu
hjuefXKnEgV4We0+UXgVCwOPjdAvBbI+e0ocS3MFEvzG6uBQE3xDk3SzynTnjh8BCNAw1FtxNrQH
usEwMFxIt4I7mKZ9YIqioymCzLq9gwQbooMDQaHWBfEbwrbwqHyGO0aoSCqI3Haadr8faqU9GY/r
OPNk3sgrDQoo//fb4hVC1CLQJ13hef4Y53CIrU7m2Ys6xt0nUW7/vGT1M0NPAgMBAAGjQjBAMA4G
A1UdDwEB/wQEAwIBBjAPBgNVHRMBAf8EBTADAQH/MB0GA1UdDgQWBBR5tFnme7bl5AFzgAiIyBpY
9umbbjANBgkqhkiG9w0BAQsFAAOCAgEAVR9YqbyyqFDQDLHYGmkgJykIrGF1XIpu+ILlaS/V9lZL
ubhzEFnTIZd+50xx+7LSYK05qAvqFyFWhfFQDlnrzuBZ6brJFe+GnY+EgPbk6ZGQ3BebYhtF8GaV
0nxvwuo77x/Py9auJ/GpsMiu/X1+mvoiBOv/2X/qkSsisRcOj/KKNFtY2PwByVS5uCbMiogziUwt
hDyC3+6WVwW6LLv3xLfHTjuCvjHIInNzktHCgKQ5ORAzI4JMPJ+GslWYHb4phowim57iaztXOoJw
TdwJx4nLCgdNbOhdjsnvzqvHu7UrTkXWStAmzOVyyghqpZXjFaH3pO3JLF+l+/+sKAIuvtd7u+Nx
e5AW0wdeRlN8NwdCjNPElpzVmbUq4JUagEiuTDkHzsxHpFKVK7q4+63SM1N95R1NbdWhscdCb+ZA
JzVcoyi3B43njTOQ5yOf+1CceWxG1bQVs5ZufpsMljq4Ui0/1lvh+wjChP4kqKOJ2qxq4RgqsahD
YVvTH9w7jXbyLeiNdd8XM2w9U/t7y0Ff/9yi0GE44Za4rF2LN9d11TPAmRGunUHBcnWEvgJBQl9n
JEiU0Zsnvgc/ubhPgXRR4Xq37Z0j4r7g1SgEEzwxA57demyPxgcYxn/eR44/KJ4EBs+lVDR3veyJ
m+kXQ99b21/+jh5Xos1AnX5iItreGCc=
-----END CERTIFICATE-----
)EOF";

WiFiClientSecure tls;
PubSubClient mqtt(tls);
Adafruit_BME280 bme;

unsigned long lastPublishAt = 0;
unsigned long nextReconnectAt = 0;
unsigned long reconnectDelayMs = 1000;
const unsigned long PUBLISH_INTERVAL_MS = 60000;

void connectWiFi() {
  WiFi.mode(WIFI_STA);
  WiFi.setAutoReconnect(true);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println(" connected");
}

void syncClock() {
  // Certificate validation needs a reasonably correct clock.
  configTime(0, 0, "pool.ntp.org", "time.nist.gov");
  Serial.print("Synchronizing clock");
  time_t now = time(nullptr);
  while (now < 1700000000) {
    delay(500);
    Serial.print(".");
    now = time(nullptr);
  }
  Serial.println(" ready");
}

void connectMQTT() {
  if (mqtt.connected() || millis() < nextReconnectAt) return;

  const bool connected = mqtt.connect(
    MQTT_CLIENT_ID,
    MQTT_USERNAME,
    MQTT_PASSWORD,
    STATUS_TOPIC,
    1,
    true,
    "{\"status\":\"offline\"}"
  );

  if (connected) {
    Serial.println("MQTT connected");
    mqtt.publish(STATUS_TOPIC, "{\"status\":\"online\"}", true);
    reconnectDelayMs = 1000;
    return;
  }

  Serial.printf("MQTT failed, state=%d; retry in %lu ms\n",
    mqtt.state(), reconnectDelayMs);
  nextReconnectAt = millis() + reconnectDelayMs;
  reconnectDelayMs = min(reconnectDelayMs * 2, 60000UL);
}

void publishReading() {
  const float temperature = bme.readTemperature();
  const float humidity = bme.readHumidity();
  const float pressureHpa = bme.readPressure() / 100.0F;
  if (isnan(temperature) || isnan(humidity) || isnan(pressureHpa)) {
    Serial.println("BME280 read failed");
    return;
  }
  const String localIP = WiFi.localIP().toString();
  char payload[256];
  snprintf(payload, sizeof(payload),
    "{\"metrics\":{\"temperature\":%.2f,\"humidity\":%.2f,\"pressure_hpa\":%.2f},\"metadata\":{\"local_ip\":\"%s\"}}",
    temperature, humidity, pressureHpa, localIP.c_str());

  if (mqtt.publish(TELEMETRY_TOPIC, payload)) {
    Serial.printf("Published: %s\n", payload);
  } else {
    Serial.println("Publish failed");
  }
}

void setup() {
  Serial.begin(115200);
  // Most BME280 breakouts use 0x76; try 0x77 if yours is not found.
  if (!bme.begin(0x76)) {
    Serial.println("BME280 not found. Check wiring and I2C address.");
    while (true) delay(1000);
  }
  connectWiFi();
  syncClock();
  tls.setCACert(DEVICECAMP_CA);
  mqtt.setServer(MQTT_HOST, MQTT_PORT);
  mqtt.setBufferSize(512);
  mqtt.setKeepAlive(30);
  mqtt.setSocketTimeout(10);
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) {
    WiFi.reconnect();
    delay(100);
    return;
  }

  connectMQTT();
  mqtt.loop();

  const unsigned long now = millis();
  if (mqtt.connected() &&
      (lastPublishAt == 0 || now - lastPublishAt >= PUBLISH_INTERVAL_MS)) {
    publishReading();
    lastPublishAt = now;
  }
}

5. Flash and verify

Set WIFI_SSID and WIFI_PASSWORD, upload, then open Serial Monitor at 115200 baud. “Published” confirms a send; the metrics should appear in the workbench after the first accepted payload.