Hello,
i can'*t say much to Domotics as i'm using FHEM.
The GP2Y10 gives an analog value that is converted into digital "ticks".
This "ticks" reading is somewhat senseles without a formula.
Aerosol (fine dust) is measured in "µg/m³".
The GP2Y10 gives typical 0,5V/100µg/m³
Your value of "537" definitely is not "µg/m3" - you would see nothing besides dust
And here the problems start.
First, the ESP8266 itself converts a range from 0...1 Volt. So you need a voltage divider (4.7 KOhm / 2.2 KOhm works fine if GP2Y10 runs on 3,3V) at the analog input.
But be aware, some modules like the WeMos D1 already have this divider built in.
(Does anyone know if the NodeMCU's have it built in? I don't have one at hand so i can't check)
Second, zero is not zero.
The output voltage of the module at no dust can be 0.... 1,5 Volts according to the data sheet.
The output voltage can be 0,35...0.65 Volt per 100µg/m³.
So this sensor must be calibrated via a formula to give a meaningfull reading.
But that needs a calibrated dust meter to see where your sensor resides. Such dust meters are very expensive.
Even worse, the zero point is not fixed, it may move over time.
The Application note says:
・If monitor value Vo maintains a bigger value than the memorized Voc for a certain
period of time, this monitor value Vo should be stored in the memory of application as a new Voc.
As far as i can see the GP2Y10 sketch does not do this.
I've tried to mount the Sensor into an airtight case, letting air in through a "Hepa" filter and pulling air out with a fan.
I was hoping that would give a reliable "zero" value". It sadly does not work, it just showed that these "Hepa" Filters
do not keep off the fine dust the sensor registers.
ATM i use this formula: ((%value%-1800)*13.2)/512
The resulting value just feels not too bad.
To be honest, this is very far away from a reliable calibration.
The "1800" Value gives the zero point correction, 13.2 gives the correction for the µg/m³-Value.
Be aware that these values are for my sensor - your sensor may (and will!) differ!
If someone has an idea how a reliable calibration could be done without using a 500€ Dust Meter, please mention here.
Datasheet
https://www.sparkfun.com/datasheets/Sen ... 10au_e.pdf
Application Note:
http://www.sharp-world.com/products/dev ... appl_e.pdf
I'll placea circuit diagram and some notes about connecting the GP2Y10 here later
Greetings
Shardan
