pio/temphum: add support for multiple sensors, si7021 and dht12 as of now

platformio/temphum/src/main.cpp

@@ -38,6 +38,7 @@ static volatile enum WiFiConnectionState wifi_state = WiFiConnectionState::WAITI
 static void* service = nullptr;
 static WiFiEventHandler wifiConnectHandler, wifiDisconnectHandler;
 static Ticker wifiTimer;
+temphum::BaseSensor* sensor = nullptr;
 
 #if MQTT_BLINK
 static StopWatch blinkStopWatch;
@@ -104,7 +105,12 @@ void setup() {
     Serial.begin(115200);
 #endif
 
-    temphum::setup();
+#if CONFIG_MODULE == HOMEKIT_SI7021
+    sensor = new temphum::Si7021();
+#elif CONFIG_MODULE == HOMEKIT_DHT12
+    sensor = new temphum::DHT12();
+#endif
+    sensor->setup();
 
     auto cfg = config::read();
     if (config::isDirty(cfg)) {
@@ -170,7 +176,7 @@ void loop() {
             } else if (mqtt->diagnosticsStopWatch.elapsed(10000)) {
                 mqtt->sendDiagnostics();
 
-                auto data = temphum::read();
+                auto data = sensor->read();
                 PRINT("temp:");
                 PRINT(data.temp);
                 PRINT(", rh: ");

platformio/temphum/src/temphum.cpp

@@ -1,14 +1,12 @@
 #ifndef CONFIG_TARGET_ESP01
 #include <Arduino.h>
 #endif
-
+#include <homekit/logging.h>
 #include "temphum.h"
 
 namespace homekit::temphum {
 
-static const int addr = 0x40;
-
-void setup() {
+void BaseSensor::setup() const {
 #ifndef CONFIG_TARGET_ESP01
     pinMode(CONFIG_SDA_GPIO, OUTPUT);
     pinMode(CONFIG_SCL_GPIO, OUTPUT);
@@ -17,43 +15,62 @@ void setup() {
 #else
     Wire.begin();
 #endif
-
-    Wire.beginTransmission(addr);
-    Wire.write(0xfe);
-    Wire.endTransmission();
-
-    delay(500);
 }
 
-struct data read() {
-    // Request temperature measurement from the Si7021 sensor
-    Wire.beginTransmission(addr);
-    Wire.write(0xF3); // command to measure temperature
+void BaseSensor::writeCommand(int reg) const {
+    Wire.beginTransmission(dev_addr);
+    Wire.write(reg);
     Wire.endTransmission();
-
     delay(500); // wait for the measurement to be ready
+}
 
-    // Read the temperature measurement from the Si7021 sensor
-    Wire.requestFrom(addr, 2);
+SensorData Si7021::read() {
+    writeCommand(0xf3); // command to measure temperature
+    Wire.requestFrom(dev_addr, 2);
     uint16_t temp_raw = Wire.read() << 8 | Wire.read();
     double temperature = ((175.72 * temp_raw) / 65536.0) - 46.85;
 
-    // Request humidity measurement from the Si7021 sensor
-    Wire.beginTransmission(addr);
-    Wire.write(0xF5); // command to measure humidity
-    Wire.endTransmission();
-
-    delay(500); // wait for the measurement to be ready
-
-    // Read the humidity measurement from the Si7021 sensor
-    Wire.requestFrom(addr, 2);
+    writeCommand(0xf5); // command to measure humidity
+    Wire.requestFrom(dev_addr, 2);
     uint16_t hum_raw = Wire.read() << 8 | Wire.read();
     double humidity = ((125.0 * hum_raw) / 65536.0) - 6.0;
 
     return {
-        .temp = temperature,
-        .rh = humidity
+            .temp = temperature,
+            .rh = humidity
     };
 }
 
+SensorData DHT12::read() {
+    SensorData sd;
+    byte raw[5];
+
+    writeCommand(0);
+    Wire.requestFrom(dev_addr, 5);
+
+    if (Wire.available() < 5) {
+        PRINTLN("DHT12: could not read 5 bytes");
+        goto end;
+    }
+
+    // Parse the received data
+    for (uint8_t i = 0; i < 5; i++)
+        raw[i] = Wire.read();
+
+    if (((raw[0] + raw[1] + raw[2] + raw[3]) & 0xff) != raw[4]) {
+        PRINTLN("DHT12: checksum error");
+        goto end;
+    }
+
+    // Calculate temperature and humidity values
+    sd.temp = raw[2] + (raw[3] & 0x7f) * 0.1;
+    if (raw[3] & 0x80)
+        sd.temp *= -1;
+
+    sd.rh = raw[0] + raw[1] * 0.1;
+
+end:
+    return sd;
+}
+
 }

platformio/temphum/src/temphum.h

@@ -4,12 +4,34 @@
 
 namespace homekit::temphum {
 
-struct data {
-    double temp; // celsius
-    double rh; // relative humidity percentage
+struct SensorData {
+    double temp = 0; // celsius
+    double rh = 0; // relative humidity percentage
 };
 
-void setup();
-struct data read();
+
+class BaseSensor {
+protected:
+    int dev_addr;
+public:
+    explicit BaseSensor(int dev) : dev_addr(dev) {}
+    void setup() const;
+    void writeCommand(int reg) const;
+    virtual SensorData read() = 0;
+};
+
+
+class Si7021 : public BaseSensor {
+public:
+    SensorData read() override;
+    Si7021() : BaseSensor(0x40) {}
+};
+
+
+class DHT12 : public BaseSensor {
+public:
+    SensorData read() override;
+    DHT12() : BaseSensor(0x5c) {}
+};
 
 }