5. OTA-Enabled Field Device

Publish business data together with firmware version, Wi-Fi signal, uptime, and free memory. Telemetry runs on its own schedule while PxServ OTA checks remain available.

Level: Advanced · Time: 60 minutes

Requirements

ESP32 and DHT22: VCC→3V3, GND→GND, DATA→GPIO4
PxServ Arduino 1.3.0+
DHT sensor library and Adafruit Unified Sensor
An OTA-capable partition layout with enough application space

Complete sketch


#include <PxServ.h>
#include <DHT.h>
#include <WiFi.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const char* FIRMWARE_VERSION = "1.0.0";
const int DHT_PIN = 4;
const unsigned long TELEMETRY_INTERVAL_MS = 30000;
 
PxServ client(PXSERV_API_KEY);
DHT dht(DHT_PIN, DHT22);
unsigned long lastTelemetryAt = 0;
 
void publishHealth() {
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  bool sensorValid = !isnan(temperature) && !isnan(humidity);
 
  if (sensorValid) {
    client.setData("field/temperature", String(temperature, 1));
    client.setData("field/humidity", String(humidity, 1));
  }
  client.setData("field/sensor-status", sensorValid ? "normal" : "error");
  client.setData("field/firmware", client.getDeviceFirmwareVersion());
  client.setData("field/uptime-seconds", String(millis() / 1000));
  client.setData("field/free-heap-bytes", String(ESP.getFreeHeap()));
  client.setData("field/wifi-rssi-dbm", String(WiFi.RSSI()));
  client.setData("field/device-status", "online");
}
 
void setup() {
  Serial.begin(115200);
  dht.begin();
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
  client.setDeviceFirmwareVersion(FIRMWARE_VERSION);
  publishHealth();
}
 
void loop() {
  unsigned long now = millis();
  if (now - lastTelemetryAt >= TELEMETRY_INTERVAL_MS) {
    lastTelemetryAt = now;
    publishHealth();
  }
  client.checkOtaFirmware();
  delay(20);
}

Update workflow

Upload OTA-capable version 1.0.0 by USB and verify health keys.
Make a visible change, set FIRMWARE_VERSION to 1.0.1, and retain all OTA calls.
Export the main compiled .bin through Arduino IDE.
Test the PxServ OTA flow first on a backup device with stable power and Wi-Fi.
Confirm the new firmware value and reset uptime after reboot.

See OTA Feature for the complete panel workflow.

Security note

PxServ Arduino 1.3.0 source uses setInsecure() for its HTTPS clients, and the example flow does not show firmware-signature verification. For security-sensitive or commercial deployments, assess the threat model and add signed firmware, integrity verification, staged rollout, rollback, and a physical recovery path.

You have completed all 25 projects. Return to the Arduino Library reference for API details.