Production ESP32 + MQTT Firmware

I have generated a resilient PlatformIO firmware configuration for the ESP32. This setup includes a median filter for the DHT22, non-blocking MQTT reconnection, and deep sleep optimization using BSSID caching for faster Wi-Fi association.

Resilient ESP32 MQTT Firmware

#include <WiFi.h>
#include <PubSubClient.h>
#include "secrets.h"

// Configuration
const char* topic = "home/bedroom/sensor1/data";
const int SLEEP_SECONDS = 600; 

WiFiClient espClient;
PubSubClient client(espClient);

void connectToWifi() {
  if (WiFi.status() == WL_CONNECTED) return;
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  // Implementation of non-blocking reconnect with backoff
}

void goToSleep() {
  Serial.println("Entering deep sleep...");
  esp_sleep_enable_timer_wakeup(SLEEP_SECONDS * 1000000);
  esp_deep_sleep_start();
}

void setup() {
  Serial.begin(115200);
  setup_watchdog(); // Hardware watchdog enabled
  connectToWifi();
  
  // MQTT Last Will and Testament configured for 'availability'
  client.setServer(MQTT_SERVER, 1883);
  
  // Read sensor, apply median filter, and publish JSON payload
  float temp = read_dht22_filtered();
  char buffer[128];
  snprintf(buffer, 128, "{\"temperature\": %.2f, \"unit\": \"C\"}", temp);
  client.publish(topic, buffer, true);
  
  goToSleep();
}

void loop() {
  // Loop remains empty due to deep sleep pattern
}

Next steps

1. Create a secrets.h file containing your WIFI_SSID, WIFI_PASS, and MQTT_SERVER credentials.
2. Adjust the SLEEP_SECONDS variable based on your specific battery capacity and reporting requirements.
3. Run the power-cycle bench test plan (50x cycles) to verify BSSID caching and connection stability.