From aa09082d7fc1251694d01cb0e760d5d8f3fe4634 Mon Sep 17 00:00:00 2001
From: capswiz <laurent.debomy@orange.fr>
Date: Fri, 30 Dec 2011 11:16:38 +0100
Subject: [PATCH] BUG : return DHT_ERROR_CHECKSUM when temperature is negative.
 So I removed "currentTemperature &= 0x7FFF" line 208 and put "& 0x7FFF" in
 the expression line 209. Now it works with negative temperatures.

---
 DHT22.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/DHT22.cpp b/DHT22.cpp
index 7daf684..8cf45f3 100644
--- a/DHT22.cpp
+++ b/DHT22.cpp
@@ -205,8 +205,8 @@ DHT22_ERROR_t DHT22::readData()
   if(currentTemperature & 0x8000)
   {
    // Below zero, non standard way of encoding negative numbers!
-    currentTemperature &= 0x7FFF;
-    _lastTemperature = (float(currentTemperature) / 10.0) * -1.0;
+   //currentTemperature &= 0x7FFF; -> if we modify currentTemperature after computing checksum, ERROR_CHECKSUM is returned
+    _lastTemperature = (float(currentTemperature & 0x7FFF) / 10.0) * -1.0;
   }
   else
   {