NodeMCU v3 + FC-22(MQ135) do not working

[espruino-discuss]

Posted at 2016-10-04 by Aleksandrs

var mq = require("MQ135").connect(NodeMCU.A0);
>console.log(mq.getPPM())
0

[espruino-discuss]

Posted at 2016-10-04 by Ollie

Maybe the pin reference. I believe D0 may be the A0 you need. See this thread

http://forum.espruino.com/conversations/278217/

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Posted at 2016-10-04 by Aleksandrs

Pin is correct.

>analogRead(0)
=0.04203323558
>analogRead(NodeMCU.A0)
=0.04203323558
>analogRead(D0)
=0.04203323558
>console.log(mq.getPPM())
0
=undefined
> 

problem.
analogRead(); do not workign in NodeMCU v3

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Posted at 2016-10-04 by Aleksandrs

Debug:
A0 + MQ135

analogRead();
=0.14369501466

A0 + Empty

>analogRead()
=0.00391006842

Resistor 4.7k over VCC and Analog

>analogRead();
=1.00097751710

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Posted at 2016-10-05 by Wilberforce

I don't think the analogue Input on the esp8266 works properly if wifi is on, as interupts affect the reading of the adc value. If you turn wifi off, it might work...

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Posted at 2016-10-08 by Aleksandrs

Do not work.,

connected? err= null info= {
  "ip": "10.2.1.36",
  "netmask": "255.255.255.0",
  "gw": "10.2.1.1",
  "mac": "18:fe:34:cb:33:66"
 }
>console.log(mq.getPPM());
0
=undefined
>wifi.disconnect();
=undefined
>console.log(mq.getPPM());
0
=undefined
>console.log(mq.getPPM());
0
=undefined
> 

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Posted at 2016-10-08 by @allObjects

A good practice is to take the issue apart and verify each of the items. In this case, go after the analog read first as you try to get going in your NodeMCU v3 - analogRead() conversation.

Furthermore, from reading the data / spec sheet of ESP8266 (and NodeMCU), only voltage values from 0..1.0V are valid inputs for analog read on pin A0.

Reading with an open input or with a voltage outside the specified range - as 3.3V over 4k7 Ohm - are meaningless... and values above 3.3V or below (usually) -0.3V - relative to GND - just destroy the MCU... and you do not even see a smoke anymore...

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Posted at 2016-10-09 by Aleksandrs

A0 is empty

>analogRead();
=0.00879765395
>analogRead();
=0.00879765395
>analogRead();
=0.00879765395
>analogRead();
=0.00879765395

A0 + MQ135

>analogRead();
=0.31085043988
>analogRead();
=0.30889540566
>analogRead();
=0.29521016617
>analogRead();
=0.28152492668

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Posted at 2016-10-09 by Aleksandrs

I maybe found.. need get default value from analogRead()

Default: 0.00879765395
Sensor: 0.09775171065
Correction: ((Sensor-Default)*1000)*3.3

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Posted at 2016-10-16 by Aleksandrs

I now found my problem .. MQ135 Analog Out is 0-5V, ESP8266 Analog Read only from 0-1V ... now please help to rising this questions.. need Resistor divider?

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Attachments:

• devider.png
  
• mq135.png