====== SHARP GP2Y1010 ======
  **reverse engineering**

Afin de mettre au point notre propre détecteur de particules fines, nous avons commencé par une phase de reverse engineering sur 2 capteurs low-cost du marché : le SHARP GP2Y1010 et le SHINYEI PPD42NS.
Ci-dessous les photos du Sharp désossé avec légendes.

{{ :wiki:projets:plume_sharp_all.png?300 |plume_sharp_all}}
{{ :wiki:projets:plume_sharp_scattered.jpg?400 |plume_sharp_scattered}}
{{ :wiki:projets:plume_sharp_circuit.jpg?500 |plume_sharp_circuit}}
{{ :wiki:projets:plume_sharp_casing.jpg?500 |plume_sharp_casing}}
{{ :wiki:projets:plume_sharp_optics.jpg?400 |plume_sharp_optics}}

Le faisceau collimaté de l'émetteur est diffusé par les particules fines. Le flux diffusé par les particules situées dans la champ optique collimaté du récepteur à un certain angle constitue la mesure. 
En pratique, ce flux est très faible. Il est le paramètre contraignant le dispositif.

  **Code**

<code=cpp>
/*
 Interface to Sharp GP2Y1010AU0F Particle Sensor
 Program by Christopher Nafis 
 Written April 2012
 
 http://www.sparkfun.com/datasheets/Sensors/gp2y1010au_e.pdf
 http://sensorapp.net/?p=479
 
 Sharp pin 1 (V-LED)   => 5V (connected to 150ohm resister)
 Sharp pin 2 (LED-GND) => Arduino GND pin
 Sharp pin 3 (LED)     => Arduino pin 2
 Sharp pin 4 (S-GND)   => Arduino GND pin
 Sharp pin 5 (Vo)      => Arduino A0 pin
 Sharp pin 6 (Vcc)     => 5V
  */
#include <SPI.h>
#include <Ethernet.h>
#include <stdlib.h>

int dustPin=0;
int ledPower=2;
int delayTime=280;
int delayTime2=40;
float offTime=9680;

int dustVal=0;
int i=0;
float ppm=0;

void setup(){
  Serial.begin(9600);
  pinMode(ledPower,OUTPUT);
  i=0;
  ppm =0;
}

void loop(){
  i=i+1;
  digitalWrite(ledPower,LOW); // power on the LED
  delayMicroseconds(delayTime);
  dustVal=analogRead(dustPin); // read the dust value
  ppm = ppm+dustVal;
  delayMicroseconds(delayTime2);
  digitalWrite(ledPower,HIGH); // turn the LED off
  delayMicroseconds(offTime);
}
</code>


====== SHINYEI PPD42NS ======

  **reverse engineering**

{{ :wiki:projets:plume_shinyei_all.jpg?400 |plume_shinyei_all}}
{{ :wiki:projets:plume_shinyei_scattered.png?400 |plume_shinyei_scattered (aqicn.org)}}

  **Code**

<code=cpp>
/*
 Interface to Shinyei Model PPD42NS Particle Sensor
 Program by Christopher Nafis 
 Written April 2012
 
 http://www.seeedstudio.com/depot/grove-dust-sensor-p-1050.html
 http://www.sca-shinyei.com/pdf/PPD42NS.pdf
 
 JST Pin 1 (Black Wire)  => Arduino GND
 JST Pin 3 (Red wire)    => Arduino 5VDC
 JST Pin 4 (Yellow wire) => Arduino Digital Pin 8
  */

int pin = 8;
unsigned long duration;
unsigned long starttime;
unsigned long sampletime_ms = 30000;
unsigned long lowpulseoccupancy = 0;
float ratio = 0;
float concentration = 0;

void setup() {
  Serial.begin(9600);
  pinMode(8,INPUT);
  starttime = millis();
}

void loop() {
  duration = pulseIn(pin, LOW);
  lowpulseoccupancy = lowpulseoccupancy+duration;

  if ((millis()-starttime) > sampletime_ms)
  {
    ratio = lowpulseoccupancy/(sampletime_ms*10.0);  // Integer percentage 0=>100
    concentration = 1.1*pow(ratio,3)-3.8*pow(ratio,2)+520*ratio+0.62; // using spec sheet curve
    Serial.print(lowpulseoccupancy);
    Serial.print(",");
    Serial.print(ratio);
    Serial.print(",");
    Serial.println(concentration);
    lowpulseoccupancy = 0;
    starttime = millis();
  }
}
</code>