Dust Sensor (1.4)

[Yveaux]

@epierre said:

The output is the AnalogOut, how can a multimeter do that ?

Just measure the output voltage. A multimeter will follow as long as the output only slowly changes.

[moo]

I would like to notice that this setup of sharp dust sensor outputs highly unreliable measurements.

Sensor should be connected as recommended in application note.
If that is so then:

• turn on IR LED (logical 0 on sharp pin 3, and optionally pause for 0.28ms),

• then analog read,

• turn off IR LED ( (logical 1).

Application note recommends taking reads 0.28ms after turning IR LED on.
Is there a reason why you skipped RC components and do not delay in microseconds?

[epierre]

@moo said:

I would like to notice that this setup of sharp dust sensor outputs highly unreliable measurements.

Yes, this is hy I asked for a moratory on the shop and went out to try other versions which are cheaper (the DSM501 and the Shinyei PPD42NS) .

I received a dead Shinyei PPD42NS, and am still in escalation on aliexpress on that.

Is there a reason why you skipped RC components and do not delay in microseconds?
You are open to try to improve the above sketch, there is no reason, this is just the implementation I found and tried out, I guess it can still be improved as your remark.

[epierre]

The SamYoung DSM501 has now its sketch :

https://github.com/empierre/arduino/blob/master/DustSensor_SamYoung_DSM501.ino

@hek this one is very cheap but much better than the SHARP GP2Y1010AU0F which reports nearly nothing... I recomment to remove it. You can use this sketch as is to replace it in the library examples, I will work further on it to provide PM1 and PM2.5 values (either or both), it looks fairly simple with a resistor and a formula, yet to be tested.

When I'll receive the Shinyei I'll do the same, given the SamYoung is its cheaper clone.

[epierre]

The Shinyei PPD42 has now its sketch :
https://github.com/empierre/arduino/blob/master/DustSensor_Shinyei_PPD42NS.ino
@hek either the SamYoung or Shinyei can be proposed, the sharp is definetly out of the race ...

Both those sensors give similar values whih is a very good point.

[epierre]

The Shinyei PPD42 has now its sketch :
https://github.com/empierre/arduino/blob/master/DustSensor_Shinyei_PPD42NS.ino
@hek either the SamYoung or Shinyei can be proposed, the sharp is definetly out of the race ...

Both those sensors give similar values whih is a very good point.

[epierre]

A good question I had from Rob:

What is the Unit of the Dust sensors ? I quess it is not in ppm ?

This is in particules per cubic inch (in imperial units) or particules per 283 ml.

I can't find a ppm conversion, at best I could do a particules per litres by multiplicating per 3.53. what do you think ?

[epierre]

ok so taking some assumptions for the PPD42NS with datasheet in particle per cubic feet:

http://billpentz.com/woodworking/cyclone/dylos.cfm

 To estimate the mass of particles in this range we simply divided by 100 to obtain micrograms per cubic meters (μg/m3) of PM2.5 respirable. The resultant value can be converted to mg/m3 if desired by dividing again by 1000. 

 PM2.5 = (753*3.53) / 100 = 25.2395 μg/m3  = 0.0252395 mg/m3

Now for the DSM501 and PPD42NS corrected, the formula to PPM:

https://en.wikipedia.org/wiki/Air_pollutant_concentrations

ppmv=mg/m3 * (0.08205*Tmp)/Molecular_mass
ppmv=0.0252395 *  (0.08205*19)/0,01 = 0,207

[epierre]

Warning on Shinyei:

The only calibration data provided by the manufacturer's datasheet is for cigarette smoke particle count concentration. Based on these data, there is an approximate error of 25% in particle measurement across most of the sensor's range. At very low concentrations, the error becomes substantial (e.g., over 50% error below 100,000 particles per cubic feet) 

http://www.researchgate.net/publication/271225140_A_distributed_network_of_low-cost_continuous_reading_sensors_to_measure_spatiotemporal_variations_of_PM2.5_in_Xi'an_China

[Tore André Rosander]

Does anyone have info on how to wire the GP2Y1010AU0F?

My cable is almost the same as on the picture https://www.mysensors.org/build/dust

The red, black and yellow is in the same place, but from there it goes white, green, blue.

EDIT: Found that Red is vcc, black is signal and yellow is ground.
Do this sensor need calibration?
And what is considered a high value for dust?

And is it only those three wires that needs to be connected to the arduino? Not the led?