Driver for I2C sensor DHT12

Refer to issue #7229

tasmota/xsns_58_dht12.ino

@@ -0,0 +1,140 @@
+/*
+  xsns_58_dht12.ino - DHT12 I2C temperature and humidity sensor support for Tasmota
+
+  Copyright (C) 2019  Stefan Oskamp and Theo Arends
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifdef USE_I2C
+#ifdef USE_DHT12
+/*********************************************************************************************\
+ * DHT12 - Temperature and Humidity
+ *
+ * I2C Address: 0x5C
+\*********************************************************************************************/
+
+#define XSNS_58              58
+#define XI2C_41              41  // See I2CDEVICES.md
+
+#define DHT12_ADDR          (uint8_t) 0x5C
+
+char    dht12_name[] = "DHT12-0x00";
+uint8_t dht12_count = 0;
+float   dht12_temperature = NAN;
+float   dht12_humidity = NAN;
+
+bool Dht12Read(void)
+{
+    Wire.beginTransmission(DHT12_ADDR);
+    Wire.write(0);
+    if (Wire.endTransmission() != 0) {
+        return false;
+    }
+    delay(50);
+    Wire.requestFrom(DHT12_ADDR, (uint8_t) 5);
+    delay(5);
+    uint8_t humidity      = Wire.read();
+    uint8_t humidityTenth = Wire.read();
+    uint8_t temp          = Wire.read();
+    uint8_t tempTenth     = Wire.read();
+    uint8_t checksum      = Wire.read();
+    dht12_humidity    = (float) humidity + (float) humidityTenth/(float) 10.0;
+    dht12_temperature = (float) temp     + (float) tempTenth/(float) 10.0;
+    return (!isnan(dht12_temperature) && !isnan(dht12_humidity));
+}
+
+void Dht12Detect(void)
+{
+    if (Dht12Read()) {
+        snprintf_P(log_data, sizeof(log_data), S_LOG_I2C_FOUND_AT, dht12_name, DHT12_ADDR);
+        AddLog(LOG_LEVEL_DEBUG);
+        snprintf_P(dht12_name, sizeof(dht12_name), PSTR("%s%c0x%02X"), "DHT12", IndexSeparator(), DHT12_ADDR);
+        dht12_count = 1;
+    }
+}
+
+void Dht12Show(bool json)
+{
+  if (dht12_count > 0)
+  {
+    char temperature[33];
+    dtostrfd(dht12_temperature, Settings.flag2.temperature_resolution, temperature);
+    char humidity[33];
+    dtostrfd(dht12_humidity, Settings.flag2.humidity_resolution, humidity);
+
+    if (json)
+    {
+      ResponseAppend_P(JSON_SNS_TEMPHUM, dht12_name, temperature, humidity);
+#ifdef USE_DOMOTICZ
+      if ((0 == tele_period))
+      {
+        DomoticzTempHumSensor(temperature, humidity);
+      }
+#endif // USE_DOMOTICZ
+
+#ifdef USE_KNX
+      if (0 == tele_period)
+      {
+        KnxSensor(KNX_TEMPERATURE, dht12_temperature);
+        KnxSensor(KNX_HUMIDITY, dht12_humidity);
+      }
+#endif // USE_KNX
+
+#ifdef USE_WEBSERVER
+    }
+    else
+    {
+      WSContentSend_PD(HTTP_SNS_TEMP, dht12_name, temperature, TempUnit());
+      WSContentSend_PD(HTTP_SNS_HUM, dht12_name, humidity);
+#endif // USE_WEBSERVER
+    }
+  }
+}
+
+
+
+/*********************************************************************************************\
+ * Interface
+\*********************************************************************************************/
+
+bool Xsns58(uint8_t function)
+{
+  if (!I2cEnabled(XI2C_41)) { return false; }
+
+  bool result = false;
+
+  if (FUNC_INIT == function) {
+    Dht12Detect();
+  }
+  else if (dht12_count > 0) {
+    switch (function) {
+    case FUNC_EVERY_SECOND:
+      Dht12Read();
+      break;
+    case FUNC_JSON_APPEND:
+      Dht12Show(1);
+      break;
+#ifdef USE_WEBSERVER
+    case FUNC_WEB_SENSOR:
+      Dht12Show(0);
+      break;
+#endif  // USE_WEBSERVER
+    }
+  }
+  return result;
+}
+
+#endif  // USE_DHT12
+#endif  // USE_I2C