#include<string.h>
#define PM1PIN 18 //DSM501A input D6 on ESP8266
#define PM25PIN 14 // ???? what
byte buff[2];
unsigned long durationPM1;
unsigned long durationPM25;
unsigned long starttime;
unsigned long endtime;
unsigned long sampletime_ms = 30000;
unsigned long lowpulseoccupancyPM1 = 0;
unsigned long lowpulseoccupancyPM25 = 0;

 
int i=0;
void setup()
{
  Serial.begin(9600);
  Serial.println("Starting please wait 30s");
  pinMode(PM1PIN,INPUT);
  pinMode(PM25PIN,INPUT);
  starttime = millis(); 
}

float calculateConcentration(long lowpulseInMicroSeconds, long durationinSeconds){
  
  float ratio = (lowpulseInMicroSeconds/1000000.0)/30.0*100.0; //Calculate the ratio
  float concentration = 0.001915 * pow(ratio,2) + 0.09522 * ratio - 0.04884;//Calculate the mg/m3
  Serial.print("lowpulseoccupancy:");
  Serial.print(lowpulseInMicroSeconds);
  Serial.print("    ratio:");
  Serial.print(ratio);
  Serial.print("    Concentration:");
  Serial.println(concentration);
  return concentration;
}

void loop()
{
  durationPM1 = pulseIn(PM1PIN, LOW);
  durationPM25 = pulseIn(PM25PIN, LOW);
  
  lowpulseoccupancyPM1 += durationPM1;
  lowpulseoccupancyPM25 += durationPM25;
  
  endtime = millis();
  if ((endtime-starttime) > sampletime_ms) //Only after 30s has passed we calcualte the ratio
  {
    // ratio1 = (lowpulseoccupancy/1000000.0)/30.0*100.0; //Calculate the ratio
    // Serial.print("ratio1: ");
    // Serial.println(ratio1);
    
    // concentration = 0.001915 * pow(ratio1,2) + 0.09522 * ratio1 - 0.04884;//Calculate the mg/m3

    float conPM1 = calculateConcentration(lowpulseoccupancyPM1,30);
    float conPM25 = calculateConcentration(lowpulseoccupancyPM25,30);
    Serial.print("PM1 ");
    Serial.print(conPM1);
    Serial.print("  PM25 ");
    Serial.println(conPM25); // this is pretty negative:)
    lowpulseoccupancyPM1 = 0;
    lowpulseoccupancyPM25 = 0;
    starttime = millis();
  } 
}