[MQ2] Gas sensor & tweak DHT config to avoid editing source when PIN is different (#1576)

Add MQ2 Gas sensor & tweak DHT config to avoid editing source when PIN is different

main/ZsensorMQ2.ino

@@ -0,0 +1,73 @@
+/*  
+  OpenMQTTGateway Addon  - ESP8266 or Arduino program for home automation 
+
+   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal  and a MQTT broker 
+   Send and receiving command by MQTT
+ 
+   This is the MQ2 GAS Sensor Addon based on modules with a MQ:
+   - Measures flammable gas
+   - Required Hardware Module: MQ2
+
+   Connection Scheme:
+   --------------------
+
+   MQ-2 -------> Arduino Uno ----------> ESP8266
+   ==============================================
+   Vcc ---------> 3.3V or 5V------------> 3.3V or 5V
+   GND ---------> GND ------------------> GND
+   A0 ----------> Pin A0 ---------------> A0
+   D0 ----------> Pin D4 ---------------> D4
+  
+    This file is part of OpenMQTTGateway.
+    
+    OpenMQTTGateway 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.
+
+    OpenMQTTGateway 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/>.
+*/
+#include "User_config.h"
+
+#ifdef ZsensorMQ2
+
+#  include "Wire.h"
+#  include "math.h"
+
+void setupZsensorMQ2() {
+  Log.notice(F("Setup MQ2 detection on pin: %d" CR), MQ2SENSORDETECTPIN);
+  pinMode(MQ2SENSORDETECTPIN, INPUT); // declare GPIOInput pin as input_pullup to prevent floating. Pin will be high when not connected to ground
+
+  Log.notice(F("Starting MQ2 calibration on pin: %d" CR), MQ2SENSORADCPIN);
+
+  //Simple calibrate
+  float sensorValue;
+  for (int x = 0; x < 1000; x++) {
+    analogRead(MQ2SENSORADCPIN);
+  }
+  delay(1000);
+
+  Log.trace(F("MQ2 Initialized." CR));
+}
+
+void MeasureGasMQ2() {
+  if (millis() > (timemq2 + TimeBetweenReadingmq2)) {
+    timemq2 = millis();
+
+    Log.trace(F("Creating MQ2 buffer" CR));
+    StaticJsonDocument<JSON_MSG_BUFFER> jsonBuffer;
+    JsonObject MQ2data = jsonBuffer.to<JsonObject>();
+
+    MQ2data["gas"] = analogRead(MQ2SENSORADCPIN);
+    MQ2data["detected"] = digitalRead(MQ2SENSORDETECTPIN) == HIGH ? "false" : "true";
+
+    pub(subjectMQ2toMQTT, MQ2data);
+  }
+}
+#endif