diff --git a/libraries/SHT2x/.arduino-ci.yml b/libraries/SHT2x/.arduino-ci.yml
index 593d2f7c..b4ab412d 100644
--- a/libraries/SHT2x/.arduino-ci.yml
+++ b/libraries/SHT2x/.arduino-ci.yml
@@ -1,3 +1,18 @@
+platforms:
+  rpipico:
+    board: rp2040:rp2040:rpipico
+    package: rp2040:rp2040
+    gcc:
+      features:
+      defines:
+        - ARDUINO_ARCH_RP2040
+      warnings:
+      flags:
+
+packages:
+  rp2040:rp2040:
+    url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+
 compile:
   # Choosing to run compilation tests on 2 different Arduino platforms
   platforms:
@@ -7,5 +22,6 @@ compile:
     # - leonardo
     - m4
     - esp32
-    # - esp8266
-    #- mega2560
+    - esp8266
+    # - mega2560
+    - rpipico
diff --git a/libraries/SHT2x/CHANGELOG.md b/libraries/SHT2x/CHANGELOG.md
new file mode 100644
index 00000000..cd260a41
--- /dev/null
+++ b/libraries/SHT2x/CHANGELOG.md
@@ -0,0 +1,43 @@
+# Change Log SHT2x
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+
+## [0.2.1] - 2022-11-24
+- Add RP2040 support to build-CI.
+- Add CHANGELOG.md
+
+
+## [0.2.0] - 2022-07-10
+- Fix #11 RawTemp + rawHum (kudos to theandy94)
+- add experimental getResolution() + setResolution()
+- adjust read delay
+- add experimental batteryOK()
+- add CRC in read() - no fail.
+
+----
+
+## [0.1.4] - 2022-06-21
+- Fix #9 ESP32 wire.begin()
+- Fix getEIDB() bug.
+
+## [0.1.3] - 2021-12-28
+- update library.json 
+- update license
+- minor edits
+
+## [0.1.2] - 2021-09-29  
+- Add Si70xx derived classes
+- add getEIDA(), getEIDB(), getFirmwareVersion()
+- update build-CI, readme.md badges
+
+## [0.1.1] - 2021-09-28  
+- Add HTU2x derived classes,
+- update readme.md + add some status info
+
+## [0.1.0] - 2021-09-25
+- initial version
+
diff --git a/libraries/SHT2x/README.md b/libraries/SHT2x/README.md
index 27db3014..e5f67eed 100644
--- a/libraries/SHT2x/README.md
+++ b/libraries/SHT2x/README.md
@@ -187,20 +187,11 @@ Timing in milliseconds.
 
 ## Future
 
-- test test test
-  - get hardware
-- investigate resolution anomalies
+#### must
 - improve documentation
-- fix TODO in code (.cpp and .h)
-- add examples
-  - test resolutions
-  - performance different resolutions
-  - test battery
-- update unit tests
 
 
 #### 0.3.0
-
 - add crc8 check (need sensor)
 - improve error handling (all code paths)
 - investigate blocking delay() in read 
@@ -208,6 +199,22 @@ Timing in milliseconds.
   - **void requestTemperature()** ==> **void readTemperature()**
   - **void requestHumidity()** ==> **void readHumidity()**
 
+
+#### should
+- test test test
+  - get hardware
+- add examples
+  - test resolutions
+  - performance different resolutions
+  - test battery
+
+
+#### could
+- investigate resolution anomalies
+- fix TODO in code (.cpp and .h)
+- update unit tests
+
+
 #### wont
 
 - add **getSerialNumber()**
diff --git a/libraries/SHT2x/SHT2x.cpp b/libraries/SHT2x/SHT2x.cpp
index 8e700ef6..421abe78 100644
--- a/libraries/SHT2x/SHT2x.cpp
+++ b/libraries/SHT2x/SHT2x.cpp
@@ -1,28 +1,10 @@
 //
 //    FILE: SHT2x.cpp
 //  AUTHOR: Rob Tillaart, Viktor Balint
-// VERSION: 0.2.0
+// VERSION: 0.2.1
 //    DATE: 2021-09-25
 // PURPOSE: Arduino library for the SHT2x temperature and humidity sensor
 //     URL: https://github.com/RobTillaart/SHT2x
-//
-
-//  HISTORY:
-//  0.1.0   2021-09-25  initial version
-//  0.1.1   2021-09-28  Add HTU2x derived classes,
-//                      update readme.md + add some status info
-//  0.1.2   2021-09-29  Add Si70xx derived classes
-//                      add getEIDA(), getEIDB(), getFirmwareVersion()
-//                      update build-CI, readme.md badges
-//  0.1.3   2021-12-28  update library.json, license, minor edits
-//  0.1.4   2022-06-21  Fix #9 ESP32 wire.begin()
-//                      Fix getEIDB() bug.
-//
-//  0.2.0   2022-07-10  Fix #11 RawTemp + rawHum (kudos to theandy94)
-//                      add experimental getResolution() + setResolution()
-//                      adjust read delay
-//                      add experimental batteryOK()
-//                      add CRC in read() - no fail.
 
 
 #include "SHT2x.h"
@@ -35,7 +17,7 @@
 #define SHT2x_WRITE_USER_REGISTER       0xE6
 #define SHT2x_READ_USER_REGISTER        0xE7
 
-#define SHT2x_HEATER_TIMEOUT            180000UL  // milliseconds
+#define SHT2x_HEATER_TIMEOUT            180000UL  //  milliseconds
 
 #define SHT2x_ADDRESS                   0x40
 
diff --git a/libraries/SHT2x/SHT2x.h b/libraries/SHT2x/SHT2x.h
index 7bf1ad16..1d907336 100644
--- a/libraries/SHT2x/SHT2x.h
+++ b/libraries/SHT2x/SHT2x.h
@@ -2,7 +2,7 @@
 //
 //    FILE: SHT2x.h
 //  AUTHOR: Rob Tillaart, Viktor Balint
-// VERSION: 0.2.0
+// VERSION: 0.2.1
 //    DATE: 2021-09-25
 // PURPOSE: Arduino library for the SHT2x temperature and humidity sensor
 //     URL: https://github.com/RobTillaart/SHT2x
@@ -13,7 +13,7 @@
 #include "Wire.h"
 
 
-#define SHT2x_LIB_VERSION             (F("0.2.0"))
+#define SHT2x_LIB_VERSION             (F("0.2.1"))
 
 
 //  fields getStatus
@@ -119,7 +119,7 @@ public:
   bool      batteryOK();
 
 
-private:
+protected:
   uint8_t   crc8(const uint8_t *data, uint8_t len);
 
   bool      writeCmd(uint8_t cmd);
@@ -127,9 +127,9 @@ private:
   bool      readBytes(uint8_t n, uint8_t *val, uint8_t maxDuration);
   TwoWire* _wire;
 
-  uint8_t   _heatTimeout;   // seconds
+  uint8_t   _heatTimeout;   //  seconds
   uint32_t  _lastRead;
-  uint32_t  _lastRequest;   // for async interface
+  uint32_t  _lastRequest;   //  for async interface
   uint32_t  _heaterStart;
   uint32_t  _heaterStop;
   bool      _heaterOn;
diff --git a/libraries/SHT2x/examples/SHT2x_test_CRC/.arduino-ci.yml b/libraries/SHT2x/examples/SHT2x_test_CRC/.arduino-ci.yml
new file mode 100644
index 00000000..59aad72b
--- /dev/null
+++ b/libraries/SHT2x/examples/SHT2x_test_CRC/.arduino-ci.yml
@@ -0,0 +1,27 @@
+platforms:
+  rpipico:
+    board: rp2040:rp2040:rpipico
+    package: rp2040:rp2040
+    gcc:
+      features:
+      defines:
+        - ARDUINO_ARCH_RP2040
+      warnings:
+      flags:
+
+packages:
+  rp2040:rp2040:
+    url: https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
+
+compile:
+  # Choosing to run compilation tests on 2 different Arduino platforms
+  platforms:
+    # - uno
+    # - due
+    # - zero
+    # - leonardo
+    # - m4
+    # - esp32
+    # - esp8266
+    # - mega2560
+    # - rpipico
diff --git a/libraries/SHT2x/examples/SHT2x_test_CRC/SHT2x_test_CRC.ino b/libraries/SHT2x/examples/SHT2x_test_CRC/SHT2x_test_CRC.ino
new file mode 100644
index 00000000..09b7fae1
--- /dev/null
+++ b/libraries/SHT2x/examples/SHT2x_test_CRC/SHT2x_test_CRC.ino
@@ -0,0 +1,41 @@
+//
+//    FILE: SHT2x_demo.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo
+//     URL: https://github.com/RobTillaart/SHT2x
+
+
+#include "Wire.h"
+#include "SHT2x.h"
+
+uint32_t start;
+uint32_t stop;
+
+SHT2x sht;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("SHT2x_LIB_VERSION: \t");
+  Serial.println(SHT2x_LIB_VERSION);
+
+  sht.begin();
+
+//  uint8_t buf[3] = { 0x7C, 0x82, 0 };
+//  Serial.println(sht.crc8(buf, 2), HEX);  // 97
+//  uint8_t buf[3] = { 0x68, 0x3A, 0 };
+//  Serial.println(sht.crc8(buf, 2), HEX);  // 7C
+  uint8_t buf[3] = { 0x4E, 0x85, 0 };
+  Serial.println(sht.crc8(buf, 2), HEX);   // 6B
+}
+
+
+void loop()
+{
+
+}
+
+
+// -- END OF FILE --
diff --git a/libraries/SHT2x/library.json b/libraries/SHT2x/library.json
index 58d0b24e..fe11faeb 100644
--- a/libraries/SHT2x/library.json
+++ b/libraries/SHT2x/library.json
@@ -18,7 +18,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/SHT2x.git"
   },
-  "version": "0.2.0",
+  "version": "0.2.1",
   "license": "MIT",
   "frameworks": "arduino",
   "platforms": "*",
diff --git a/libraries/SHT2x/library.properties b/libraries/SHT2x/library.properties
index c787dcfd..cf208603 100644
--- a/libraries/SHT2x/library.properties
+++ b/libraries/SHT2x/library.properties
@@ -1,5 +1,5 @@
 name=SHT2x
-version=0.2.0
+version=0.2.1
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for the I2C SHT20 SHT21 SHT25 series temperature and humidity sensor.