Grove - Dust Sensor in ug/m3

Dear all,

I have built the same Grove dust sensor as on this link:

Building it and program it with the Arduino IDE is not a problem. I use the same code as in the link. The dust sensor (PPD42NS) is a sensitive sensor and sense the dust very good in pcs/liter. I want the results in ug/m3 so I must change the code.

What I also want to know is how it calculates the lowpulseoccupancy exactly. The sentence below is for my not clear enough.

“You just measure how long the digital signal on Pin 8 is low during the 30 second sample time. This ratio is used in a transfer function to calculate the particles per 0.01 cubic feet.”

How come the digital signal become low, because dust is present?

I know that this is a old post, but still I would like to answer.
The transfer function that was mentioned in that project was the function between LPO and concentration, generated by that project’s author, using a curve fitting on the Cigarette smoke graph (LPO vs Concnetration).

@vineeth_2808 Thank you for your participation