Shinyei PPD42 Particle Sensor
Tracy Allen wrote an excellent article: De-construction of the Shinyei PPD42NS dust sensor which describes how the sensor works and includes a schematic.
| Pin | Function | Wire color (in picture above) |
|---|---|---|
| 1 | Ground | Green |
| 2 | P2 (output) | White |
| 3 | 5V | Yellow |
| 4 | P1 (output) | Black |
| 5 | Threshold voltage for P2 | Red |
Pin 5 is closest to the corner of the board (and there is a 5 printed on both sides of the board near pin 5). Note the colors in the photo above are different from the wire colors available from other sources (like Grove).
The P1 output is used to measure particles between 1um and 10um. The P2 output (with the threshold pin unconnected) is used to measure particles between 2.5um and 10um.
This particular sensor uses a heater resistor to induce airflow, and requires that the sensor be oriented vertically (with the connector at the bottom and the metal portion at the top). Based on some information (see Pickle discussions below) using a fan provides better data.
To read the sensor, the total time that the P1 or P2 signal is low (measured in microsends) is used to determine particle concentrations.
Datasheets / Information