From 6fa68db79f0e2e549bb1239c4464956dd27d8f9b Mon Sep 17 00:00:00 2001
From: Sarah Knepper <sarah.knepper@intel.com>
Date: Thu, 4 Dec 2014 10:35:51 +0000
Subject: [PATCH] grove.cxx: change lux formula used in GroveLight

Signed-off-by: Sarah Knepper <sarah.knepper@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
---
 src/grove/grove.cxx | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/grove/grove.cxx b/src/grove/grove.cxx
index fd4ffbae..fc79760f 100644
--- a/src/grove/grove.cxx
+++ b/src/grove/grove.cxx
@@ -1,6 +1,7 @@
 /*
  * Author: Brendan Le Foll <brendan.le.foll@intel.com>
  * Contributions: Mihai Tudor Panu <mihai.t.panu@intel.com>
+ * Contributions: Sarah Knepper <sarah.knepper@intel.com>
  * Copyright (c) 2014 Intel Corporation.
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -106,10 +107,10 @@ GroveLight::~GroveLight()
 
 int GroveLight::value ()
 {
-    // rough conversion to Lux
-    int a = mraa_aio_read(m_aio);
-    a = 10000/(((1023-a)*10/a)*15)^(4/3);
-    return a;
+    // rough conversion to lux, using formula from Grove Starter Kit booklet
+    float a = (float) mraa_aio_read(m_aio);
+    a = 10000.0/pow(((1023.0-a)*10.0/a)*15.0,4.0/3.0);
+    return (int) round(a);
 }
 
 float GroveLight::raw_value()