From c146aa2d048b10d1c760e7681fa039ee495fe98d Mon Sep 17 00:00:00 2001
From: epierre <epierre@e-nef.com>
Date: Mon, 10 Aug 2015 22:03:59 +0200
Subject: [PATCH] formula is back

---
 .../examples/DustSensor/DustSensor_SamYoung_DSM501.ino     | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libraries/MySensors/examples/DustSensor/DustSensor_SamYoung_DSM501.ino b/libraries/MySensors/examples/DustSensor/DustSensor_SamYoung_DSM501.ino
index 50514c8..43cae33 100644
--- a/libraries/MySensors/examples/DustSensor/DustSensor_SamYoung_DSM501.ino
+++ b/libraries/MySensors/examples/DustSensor/DustSensor_SamYoung_DSM501.ino
@@ -97,8 +97,13 @@ void loop()
   Serial.print("PM10: ");
   Serial.println(concentrationPM10);
   Serial.print("\n");
+  //ppmv=mg/m3 * (0.08205*Tmp)/Molecular_mass
+  //0.08205   = Universal gas constant in atm·m3/(kmol·K)
+  int temp=20; //external temperature, if you can replace this with a DHT11 or better 
+  long ppmv=(concentrationPM10*0.0283168/100/1000) *  (0.08205*temp)/0.01;
+  
   if ((ceil(concentrationPM10) != lastDUSTPM10)&&((long)concentrationPM10>0)) {
-      gw.send(dustMsgPM10.set((long)ceil(concentrationPM10)));
+      gw.send(dustMsgPM10.set((long)ppmv));
       lastDUSTPM10 = ceil(concentrationPM10);
   }