MQ Sensor support

The MQ1--9 sensors are now supported by USE_MQ_SENSOR option.

Sensor supply is 5V the additional voltage divider measurement is needed, and separate supply for ESP by i.e. voltage converter 3.3 => 5v

https://www.google.pl/search?q=3.3V+to+5V+DC-DC+converter&dcr=0&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiQ_rW6-q7ZAhUJ3CwKHWGfCxsQsAQIOw&biw=1350&bih=576

and,

http://www.ohmslawcalculator.com/voltage-divider-calculator

For clear ADC input, there is: R1=1mohm R2=250kohm (1% tolerance) divider that gives 1.0V max output (ESP ADC max value) when the input is 5.0V ESP Wemeos D1 - divider has max 3.3V input A0, For a module, without a divider, you have to count new values for adding a divider to ADC D1 Wemeos that has 330kohm summarised value of divider - need to be replaced or added an additional resistor for a double divider For 5V you have to use only one serial input A0 resistor 165kohm between the output of MQ sensor and input A0 it gives 3.299V for A0. See https://escapequotes.net/wp-content/uploads/2017/06/esp8266-wemos-d1-mini-pro-schematics.png https://electronics.stackexchange.com/questions/197105/multiple-voltage-dividers Description: MQ_SENSOR - GAS sensor for MQ-5 for others the RS_air need to be set http://wiki.seeed.cc/Grove-Gas_Sensor-MQ5/

Source taken for creation: http://sandboxelectronics.com/?p=165 https://www.mysensors.org/build/gas https://github.com/mdsiraj1992/Gassensors/blob/master/arduino%20codes/mq5_sensor/mq5_sensor.ino

/MQsensor************************************ choice proper MQ sensor according codes for mq2, mq3, mq4, mq5, mq6, mq7, mq8, mq9, mq135