ESP8266 Gas sensor connection

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1

Hello,

I have an ESP-12E ESP8266 wifi module and a Gas sensor (MQ-7) which has analog ouput. I know the sensor can not be connected directly to the module.Is there anyway such that I can read sensor data from ESP-12E.

2

The ADC pin on the ESP8266 requires that the voltage on the pin is between 0 and 1 volt. So wire it up normally, then use a pair of resitors as voltage divider to get it into the 0~1v range.

3

DrAzzy:
The ADC pin on the ESP8266 requires that the voltage on the pin is between 0 and 1 volt.

What about the voltage on the GPIO pins ?

4

Harikishore:
What about the voltage on the GPIO pins ?

The merely means that the ADC has a reference voltage of one Volt, and will not measure above that. The same is true of the Arduino with its internal reference.

Now while the sensor heater is specified at 5 V (or apparently, 1.4) and 5 V is specified in the test conditions, there is no evident reason why the sensor itself cannot be powered by 3.3 V, so a single resistor from the 3.3 V supply to the sensor and ADC input, with the sensor between this point and ground, should work quite well.

5

Does anyone know how to multiplex ADC pin of ESP-12E ? So that I can connect more than one sensor.

I saw this link ESP8266 ADC - Miltiple Analog Sensors but this one uses Node MCU, I don't know that.I usually program esp8266 on Arduino IDE.

6

Multiplexing problem has been solved.

Does anyone know the commands in Arduino IDE to read value from ADC pin of esp-12e.

7

PLEASE PROVIDE ME THE CKT DIAGRAM FOR CONNECTION OF MQ2 SMOKE DETECTOR AND ESP8266(WIFI MODULE) FOR MESSAGE ALERT

8

DrAzzy:
The ADC pin on the ESP8266 requires that the voltage on the pin is between 0 and 1 volt. So wire it up normally, then use a pair of resitors as voltage divider to get it into the 0~1v range.

Hello DrAzzy,

Would you mind elaborating a little bit on the pair of resistors as voltage divider?

I'm trying to wire a MQ-7 up on a ESP8266 12f, but I'm running into troubles with the analog input pin.

Thanks,
Marcelo

9

marcelops:
Hello DrAzzy,

Would you mind elaborating a little bit on the pair of resistors as voltage divider?

I'm trying to wire a MQ-7 up on a ESP8266 12f, but I'm running into troubles with the analog input pin.

Thanks,
Marcelo

Since ESP8266 Analog pin expects 0-1V, you need to step down the output of the Gas sensor which is 0-5V, You could use 400K and 110K in series to achieve the result. The voltage across 110K resistance should be 0-1V. I am using MQ-5 gas sensor.