BMP280_AHT20

platformio.ini

@@ -10,6 +10,8 @@ lib_deps = SPI
            https://github.com/adafruit/Adafruit_TSL2561
            https://github.com/knolleary/pubsubclient
            https://github.com/adafruit/Adafruit_BME680
+           https://github.com/adafruit/Adafruit_BMP280
+           https://github.com/adafruit/Adafruit_AHTX0
            https://github.com/phassel/ArduPID/
            https://github.com/me-no-dev/ESPAsyncWebServer
            https://github.com/wayoda/LedControl

src/Greenhouse.cpp

@@ -1,19 +1,20 @@
 #ifdef NODE_GREENHOUSE
 
 #include "patrix/tsl2561.h"
-#include "patrix/DHT22.h"
+#include "patrix/bmp280_aht20.h"
 
-TSL2561 greenhouseTSL("greenhouse");
+TSL2561 greenhouse_TSL2561("greenhouse");
 
-DHT22Sensor greenhouseDHT22("greenhouse", D5);
+BMP280_AHT20 greenhouse_BMP280_AHT20("greenhouse");
 
 void patrixSetup() {
-  greenhouseTSL.setup();
+  greenhouse_TSL2561.setup();
+  greenhouse_BMP280_AHT20.setup();
 }
 
 void patrixLoop() {
-  greenhouseTSL.loop();
-  greenhouseDHT22.loop();
+  greenhouse_TSL2561.loop();
+  greenhouse_BMP280_AHT20.loop();
 }
 
 #endif

src/patrix/bmp280_aht20.h

@@ -0,0 +1,105 @@
+#ifndef BMP280_H
+#define BMP280_H
+
+#include "Adafruit_BMP280.h"
+#include "Adafruit_AHTX0.h"
+#include "mqtt.h"
+
+class BMP280_AHT20 {
+
+  Adafruit_BMP280 sensor;
+
+  Adafruit_AHTX0 aht20;
+
+  unsigned long last = 0UL;
+
+public:
+
+  const String name;
+
+  unsigned long intervalMs;
+
+  explicit BMP280_AHT20(String name, const unsigned long interval_ms = 5000) : name(std::move(name)), intervalMs(interval_ms) {
+    //
+  }
+
+  void setup() {
+    bmp280Setup();
+    aht20Setup();
+  }
+
+  void bmp280Setup() {
+    if (sensor.begin()) {
+      Log.info("BMP280 \"%s\": Initialized.", name.c_str());
+      sensor.setSampling(
+        Adafruit_BMP280::MODE_NORMAL,
+        Adafruit_BMP280::SAMPLING_X16,
+        Adafruit_BMP280::SAMPLING_X16,
+        Adafruit_BMP280::FILTER_X16,
+        Adafruit_BMP280::STANDBY_MS_500
+      );
+    } else {
+      Log.error("BMP280 \"%s\": Failed to initialize.", name.c_str());
+    }
+  }
+
+  void aht20Setup() {
+    if (aht20.begin()) {
+      Log.info("AHT20 \"%s\": Initialized.", name.c_str());
+    } else {
+      Log.error("AHT20 \"%s\": Failed to initialize.", name.c_str());
+    }
+  }
+
+  void loop() {
+    const auto now = max(1UL, millis());
+    if (last != 0 && now - last < intervalMs) {
+      return;
+    }
+
+    last = now;
+    bmp280Read();
+    aht20Read();
+  }
+
+  void bmp280Read() {
+    const auto pressure = sensor.readPressure();
+    if (isnan(pressure)) {
+      Log.error("BMP280 \"%s\": Failed to read", name.c_str());
+      bmp280Setup();
+      return;
+    }
+
+    mqttPublishValue(name + "/pressure", pressure / 100.0, "PRESSURE_HPA");
+  }
+
+  void aht20Read() {
+    sensors_event_t temperature{};
+    sensors_event_t relative{};
+    if (!aht20.getEvent(&relative, &temperature)) {
+      Log.error("AHT20 \"%s\": Failed to read", name.c_str());
+      aht20Setup();
+      return;
+    }
+
+    const auto absolute = calculateHumidityAbsolute(temperature.temperature, relative.relative_humidity);
+    mqttPublishValue(name + "/temperature", temperature.temperature, "TEMPERATURE_C");
+    mqttPublishValue(name + "/relative", relative.relative_humidity, "HUMIDITY_RELATIVE_PERCENT");
+    mqttPublishValue(name + "/absolute", absolute, "HUMIDITY_ABSOLUTE_GM3");
+  }
+
+  static double calculateHumidityAbsolute(const double temperature, const double humidityRelative) {
+    constexpr auto A = 6.112;
+    constexpr auto m = 17.67;
+    constexpr auto Tn = 243.5;
+    constexpr auto Mw = 18.01534;
+    constexpr auto R = 8.314462618;
+    const auto Tk = temperature + 273.15;
+    const auto P_sat = A * exp((m * temperature) / (temperature + Tn));
+    const auto P_act = P_sat * (humidityRelative / 100.0);
+    return (P_act * Mw) / (R * Tk);
+  }
+
+};
+
+#endif