diff --git a/libraries/MCP9808_RT/LICENSE b/libraries/MCP9808_RT/LICENSE
index 8eba944a..c3d6b3da 100644
--- a/libraries/MCP9808_RT/LICENSE
+++ b/libraries/MCP9808_RT/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2020-2021 Rob Tillaart
+Copyright (c) 2020-2022 Rob Tillaart
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/libraries/MCP9808_RT/examples/mcp9808_minimum/mcp9808_minimum.ino b/libraries/MCP9808_RT/examples/mcp9808_minimum/mcp9808_minimum.ino
index 70c43aa6..10fa774e 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_minimum/mcp9808_minimum.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_minimum/mcp9808_minimum.ino
@@ -1,7 +1,6 @@
 //
 //    FILE: mcp9808_minimum.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo
 //    DATE: 2020-11-12
 
diff --git a/libraries/MCP9808_RT/examples/mcp9808_offset/mcp9808_offset.ino b/libraries/MCP9808_RT/examples/mcp9808_offset/mcp9808_offset.ino
index f4242096..a95be7e3 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_offset/mcp9808_offset.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_offset/mcp9808_offset.ino
@@ -1,7 +1,6 @@
 //
 //    FILE: mcp9808_offset.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo
 //    DATE: 2020-11-13
 
diff --git a/libraries/MCP9808_RT/examples/mcp9808_performance/mcp9808_performance.ino b/libraries/MCP9808_RT/examples/mcp9808_performance/mcp9808_performance.ino
index 30233d21..de1833d4 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_performance/mcp9808_performance.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_performance/mcp9808_performance.ino
@@ -1,7 +1,6 @@
 //
 //    FILE: mcp9808_performance.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo
 //    DATE: 2020-11-13
 
diff --git a/libraries/MCP9808_RT/examples/mcp9808_setResolution/mcp9808_setResolution.ino b/libraries/MCP9808_RT/examples/mcp9808_setResolution/mcp9808_setResolution.ino
index ab8564b9..2710782f 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_setResolution/mcp9808_setResolution.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_setResolution/mcp9808_setResolution.ino
@@ -1,7 +1,6 @@
 //
 //    FILE: mcp9808_setResolution.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo
 //    DATE: 2020-11-13
 
diff --git a/libraries/MCP9808_RT/examples/mcp9808_test/mcp9808_test.ino b/libraries/MCP9808_RT/examples/mcp9808_test/mcp9808_test.ino
index b0b0b6a2..d68f1a18 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_test/mcp9808_test.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_test/mcp9808_test.ino
@@ -1,11 +1,8 @@
 //
 //    FILE: mcp9808_test.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.1
 // PURPOSE: demo
 //    DATE: 2020-05-03
-//    (c) : MIT
-//
 
 
 #include "mcp9808.h"
diff --git a/libraries/MCP9808_RT/examples/mcp9808_test_alert/mcp9808_test_alert.ino b/libraries/MCP9808_RT/examples/mcp9808_test_alert/mcp9808_test_alert.ino
index 1cc23537..67bceb39 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_test_alert/mcp9808_test_alert.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_test_alert/mcp9808_test_alert.ino
@@ -1,12 +1,8 @@
 //
 //    FILE: mcp9808_test_alert.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo alert
 //    DATE: 2020-11-12
-//    (c) : MIT
-//
-
 //
 //  MCP9808 breakout board
 //  +----------+
diff --git a/libraries/MCP9808_RT/examples/mcp9808_test_alert_irq/mcp9808_test_alert_irq.ino b/libraries/MCP9808_RT/examples/mcp9808_test_alert_irq/mcp9808_test_alert_irq.ino
index 9b9f2e84..e61dd270 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_test_alert_irq/mcp9808_test_alert_irq.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_test_alert_irq/mcp9808_test_alert_irq.ino
@@ -1,12 +1,8 @@
 //
 //    FILE: mcp9808_test_alert_irq.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo alert to interrupt 0 = PIN2 of Arduino UNO.
 //    DATE: 2020-11-16
-//    (c) : MIT
-//
-
 //
 //  MCP9808 breakout board
 //  +----------+
@@ -29,6 +25,7 @@ MCP9808 ts(24);
 const uint8_t ALERTPIN = 2;     // ADJUST IF NEEDED
 volatile bool flag = false;
 
+
 // interrupt routine
 void detectAlert()
 {
diff --git a/libraries/MCP9808_RT/examples/mcp9808_test_alert_polling/mcp9808_test_alert_polling.ino b/libraries/MCP9808_RT/examples/mcp9808_test_alert_polling/mcp9808_test_alert_polling.ino
index ffb1435f..167d09c4 100644
--- a/libraries/MCP9808_RT/examples/mcp9808_test_alert_polling/mcp9808_test_alert_polling.ino
+++ b/libraries/MCP9808_RT/examples/mcp9808_test_alert_polling/mcp9808_test_alert_polling.ino
@@ -1,12 +1,8 @@
 //
 //    FILE: mcp9808_test_alert_polling.ino
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.0
 // PURPOSE: demo alert to PIN5 of Arduino UNO.
 //    DATE: 2020-11-16
-//    (c) : MIT
-//
-
 //
 //  MCP9808 breakout board
 //  +----------+
@@ -82,3 +78,4 @@ void loop()
 
 
 // -- END OF FILE --
+
diff --git a/libraries/MCP9808_RT/keywords.txt b/libraries/MCP9808_RT/keywords.txt
index ef43c90a..383f7bc9 100644
--- a/libraries/MCP9808_RT/keywords.txt
+++ b/libraries/MCP9808_RT/keywords.txt
@@ -1,8 +1,10 @@
 # Syntax Colouring Map For MCP9808
 
+
 # Data types (KEYWORD1)
 MCP9808	KEYWORD1
 
+
 # Methods and Functions (KEYWORD2)
 setAddress	KEYWORD2
 setConfigRegister	KEYWORD2
@@ -31,6 +33,7 @@ getRevision	KEYWORD2
 
 # Constants (LITERAL1)
 MCP9808_LIB_VERSION	LITERAL1
+
 MCP9808_THYSTERESIS	LITERAL1
 MCP9808_SHUTDOWN	LITERAL1
 MCP9808_CRIT_LOCK	LITERAL1
diff --git a/libraries/MCP9808_RT/library.json b/libraries/MCP9808_RT/library.json
index 73f8be0d..aae538a9 100644
--- a/libraries/MCP9808_RT/library.json
+++ b/libraries/MCP9808_RT/library.json
@@ -15,8 +15,9 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/MCP9808_RT.git"
   },
-  "version": "0.1.4",
+  "version": "0.2.1",
   "license": "MIT",
   "frameworks": "arduino",
-  "platforms": "*"
+  "platforms": "*",
+  "headers": "mcp9808.h"
 }
diff --git a/libraries/MCP9808_RT/library.properties b/libraries/MCP9808_RT/library.properties
index 2af0c752..6585c815 100644
--- a/libraries/MCP9808_RT/library.properties
+++ b/libraries/MCP9808_RT/library.properties
@@ -1,5 +1,5 @@
 name=MCP9808_RT
-version=0.1.4
+version=0.2.1
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino Library for I2C MCP9808 temperature sensor
diff --git a/libraries/MCP9808_RT/mcp9808.cpp b/libraries/MCP9808_RT/mcp9808.cpp
index dad58413..1c6823c9 100644
--- a/libraries/MCP9808_RT/mcp9808.cpp
+++ b/libraries/MCP9808_RT/mcp9808.cpp
@@ -1,7 +1,7 @@
 //
 //    FILE: mcp9808.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.4
+// VERSION: 0.2.1
 // PURPOSE: Arduino Library for I2C mcp9808 temperature sensor
 //    DATE: 2020-05-03
 //     URL: https://github.com/RobTillaart/MCP9808_RT
@@ -11,10 +11,12 @@
 //  0.1.1   2020-11-12  refactor
 //  0.1.2   2020-11-16  removed hasAlert, removed setAlertPin, 
 //                      added 2 alert examples, refactor low level
-//  0.1.3   2021-01-01  arduino-ci + unit test                    
+//  0.1.3   2021-01-01  Arduino-ci + unit test
 //  0.1.4   2021-11-08  update build-CI, badges
 //                      default offset for offset
 //                      default Wire for I2C bus - setAddress()
+//  0.2.0   2021-11-19  fix #7 negative temperature
+//  0.2.1   2021-12-21  update library.json, license, minor edits
 
 
 #include "mcp9808.h"
@@ -214,7 +216,7 @@ float MCP9808::readFloat(uint8_t reg)
   }
   if (val & 0x1000)  // negative value
   {
-    return 256 - (val & 0x0FFF) * 0.0625;
+    return ((val & 0x0FFF) * 0.0625) - 256.0;
   }
   return (val & 0x0FFF) * 0.0625;
 }
diff --git a/libraries/MCP9808_RT/mcp9808.h b/libraries/MCP9808_RT/mcp9808.h
index 94ea7e18..f2d8a2a7 100644
--- a/libraries/MCP9808_RT/mcp9808.h
+++ b/libraries/MCP9808_RT/mcp9808.h
@@ -2,7 +2,7 @@
 //
 //    FILE: mcp9808.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.1.4
+// VERSION: 0.2.1
 // PURPOSE: Arduino Library for I2C mcp9808 temperature sensor
 //    DATE: 2020-05-03
 //     URL: https://github.com/RobTillaart/MCP9808_RT
@@ -17,21 +17,21 @@
 // 24..31 == 0x18..0x1F
 
 
-#define MCP9808_LIB_VERSION         (F("0.1.4"))
+#define MCP9808_LIB_VERSION               (F("0.2.1"))
 
 
 // CONFIGURATION REGISTER MASKS
 // check the datasheet for exact usage
-#define MCP9808_THYSTERESIS         0x0600
-#define MCP9808_SHUTDOWN            0x0100
-#define MCP9808_CRIT_LOCK           0x0080
-#define MCP9808_WIN_LOCK            0x0040
-#define MCP9808_INT_CLEAR           0x0020
-#define MCP9808_ALERT_STATUS        0x0010
-#define MCP9808_ALERT_CTRL          0x0008
-#define MCP9808_ALERT_SELECT        0x0004
-#define MCP9808_ALERT_POLAR         0x0002
-#define MCP9808_ALERT_MODE          0x0001
+#define MCP9808_THYSTERESIS               0x0600
+#define MCP9808_SHUTDOWN                  0x0100
+#define MCP9808_CRIT_LOCK                 0x0080
+#define MCP9808_WIN_LOCK                  0x0040
+#define MCP9808_INT_CLEAR                 0x0020
+#define MCP9808_ALERT_STATUS              0x0010
+#define MCP9808_ALERT_CTRL                0x0008
+#define MCP9808_ALERT_SELECT              0x0004
+#define MCP9808_ALERT_POLAR               0x0002
+#define MCP9808_ALERT_MODE                0x0001
 
 
 class MCP9808
diff --git a/libraries/MCP9808_RT/test/unit_test_001.cpp b/libraries/MCP9808_RT/test/unit_test_001.cpp
index ad0f2a3d..0af51fe7 100644
--- a/libraries/MCP9808_RT/test/unit_test_001.cpp
+++ b/libraries/MCP9808_RT/test/unit_test_001.cpp
@@ -39,6 +39,7 @@
 
 unittest_setup()
 {
+  fprintf(stderr, "MCP9808_LIB_VERSION: %s\n", (char *) MCP9808_LIB_VERSION);
 }
 
 unittest_teardown()
@@ -46,12 +47,24 @@ unittest_teardown()
 }
 
 
-// TODO more can be tested if there is a Godmode->Wire stub
+unittest(test_constants)
+{
+  assertEqual(MCP9808_THYSTERESIS , 0x0600);
+  assertEqual(MCP9808_SHUTDOWN    , 0x0100);
+  assertEqual(MCP9808_CRIT_LOCK   , 0x0080);
+  assertEqual(MCP9808_WIN_LOCK    , 0x0040);
+  assertEqual(MCP9808_INT_CLEAR   , 0x0020);
+  assertEqual(MCP9808_ALERT_STATUS, 0x0010);
+  assertEqual(MCP9808_ALERT_CTRL  , 0x0008);
+  assertEqual(MCP9808_ALERT_SELECT, 0x0004);
+  assertEqual(MCP9808_ALERT_POLAR , 0x0002);
+  assertEqual(MCP9808_ALERT_MODE  , 0x0001);
+}
 
+
+// TODO more can be tested if there is a Godmode->Wire stub
 unittest(test_constructor)
 {
-  fprintf(stderr, "VERSION: %s\n", (char *) MCP9808_LIB_VERSION);
-
   MCP9808 ts(24);
   assertTrue(ts.setAddress(24, &Wire) );
   assertTrue(ts.isConnected());